Military User's Guide for the Certification of Aviation Platforms

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NORTH ATLANTIC TREATY SCIENCE AND TECHNOLOGY ORGANIZATION ORGANIZATION

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STO TECHNICAL REPORT TR-AVT-225

Military User’s Guide for the Certification of Aviation Platforms on Synthetic Jet Fuels (Guide d’utilisation militaire pour la certification des plateformes d’aviation alimentées par des carburéacteurs de synthèse)

Final Report of the AVT Task Group 225.

This document should be announced and supplied only to NATO, Government Agencies of NATO Nations and their bona fide contractors, and to other recipients approved by the STO National Coordinators.

Ce document ne doit être notifié et distribué qu’à l’OTAN, qu’aux instances gouvernementales des pays membres de l’OTAN, ainsi qu’à leurs contractants dûment habilités et qu’aux autres demandeurs agréés par les Coordonnateurs Nationaux de la STO.

Published July 2018

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NORTH ATLANTIC TREATY SCIENCE AND TECHNOLOGY ORGANIZATION ORGANIZATION

AC/323(AVT-225)TP/803 www.sto.nato.int

STO TECHNICAL REPORT TR-AVT-225

Final Report of the AVT Task Group 225.

This document should be announced and supplied only to NATO, Government Agencies of NATO Nations and their bona fide contractors, and to other recipients approved by the STO National Coordinators.

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The NATO Science and Technology Organization

Science & Technology (S&T) in the NATO context is defined as the selective and rigorous generation and application of state-of-the-art, validated knowledge for defence and security purposes. S&T activities embrace scientific research, technology development, transition, application and field-testing, experimentation and a range of related scientific activities that include systems engineering, operational research and analysis, synthesis, integration and validation of knowledge derived through the scientific method. In NATO, S&T is addressed using different business models, namely a collaborative business model where NATO provides a forum where NATO Nations and partner Nations elect to use their national resources to define, conduct and promote cooperative research and information exchange, and secondly an in-house delivery business model where S&T activities are conducted in a NATO dedicated executive body, having its own personnel, capabilities and infrastructure. The mission of the NATO Science & Technology Organization (STO) is to help position the Nations’ and NATO’s S&T investments as a strategic enabler of the knowledge and technology advantage for the defence and security posture of NATO Nations and partner Nations, by conducting and promoting S&T activities that augment and leverage the capabilities and programmes of the Alliance, of the NATO Nations and the partner Nations, in support of NATO’s objectives, and contributing to NATO’s ability to enable and influence security and defence related capability development and threat mitigation in NATO Nations and partner Nations, in accordance with NATO policies. The total spectrum of this collaborative effort is addressed by six Technical Panels who manage a wide range of scientific research activities, a Group specialising in modelling and simulation, plus a Committee dedicated to supporting the information management needs of the organization. • AVT Applied Vehicle Technology Panel • HFM Human Factors and Medicine Panel • IST Information Systems Technology Panel • NMSG NATO Modelling and Simulation Group • SAS System Analysis and Studies Panel • SCI Systems Concepts and Integration Panel • SET Sensors and Electronics Technology Panel These Panels and Group are the power-house of the collaborative model and are made up of national representatives as well as recognised world-class scientists, engineers and information specialists. In addition to providing critical technical oversight, they also provide a communication link to military users and other NATO bodies. The scientific and technological work is carried out by Technical Teams, created under one or more of these eight bodies, for specific research activities which have a defined duration. These research activities can take a variety of forms, including Task Groups, Workshops, Symposia, Specialists’ Meetings, Lecture Series and Technical Courses.

The content of this publication has been reproduced directly from material supplied by STO or the authors.

Published July 2018

ISBN 978-92-837-2131-4

Single copies of this publication or of a part of it may be made for individual use only by those organisations or individuals in NATO Nations defined by the limitation notice printed on the front cover. The approval of the STO Information Management Systems Branch is required for more than one copy to be made or an extract included in another publication. Requests to do so should be sent to the address on the back cover.

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Table of Contents

Page

List of Figures v List of Tables vi List of Acronyms vii AVT-225 Membership List ix

Executive Summary and Synthèse ES-1

Chapter 1 − Introduction and Motivation 1-1 1.1 Research Task Group AVT-225 1-1 1.1.1 Background 1-1 1.1.2 Mandate and Progress 1-2 1.1.3 Present Focus and Objective 1-2 1.2 Motivation for Certification of Platforms for Synthetic Fuels 1-3 1.3 Current Market Readiness Levels for Synthetic Fuels 1-6 1.4 Impact of Military’s Lagging Adoption of Synthetic Fuels 1-10 1.5 Organization of Report 1-11

Chapter 2 − Jet Fuel 101 2-1 2.1 Composition and Properties of Fossil-Based Kerosene 2-1 2.1.1 Composition of Kerosene 2-1 2.1.2 Properties of Aviation Kerosene 2-3 2.1.3 How is it Refined? 2-5 2.2 Composition and Properties of Drop-In Synthetic Kerosene 2-5 2.3 Not All Biofuels are Suitable as Jet Fuels 2-6 2.4 What are Jet Fuel Specifications? 2-7 2.4.1 Civil Specifications for Aviation Fuels 2-7 2.4.2 Military Specifications for Aviation Fuels 2-8

Chapter 3 − Jet Fuel Approval Processes 3-1 3.1 Overview of the Civil Fuel Approval Process for Alternative Jet Fuels 3-1 3.1.1 Context 3-1 3.1.2 Terms of Use of Jet Fuels on Civil Aircraft 3-1 3.1.3 Approval of Fuel from Alternative Pathways 3-2 3.1.4 Description of Steps of the General Procedure for Certification 3-3 of Jet Fuel 3.1.5 Current Developments on Alternative Fuels 3-4 3.2 Overview of the Military Fuel Approval Process for Alternative Jet Fuels 3-6

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Chapter 4 − Linkages Between Civil and Military Specifications 4-1 4.1 References to Synthetic Components in Fuel Specifications 4-1 4.1.1 ASTM D1655-16c (2016) 4-1 4.1.2 MIL-DTL-83133J (2015) JP-8 (F-34) and F-35 4-2 4.1.3 MIL-DTL-5624W (2016) – JP-5 (F-44) 4-2 4.1.4 CGSB-3.24-2016 4-3 4.1.5 Def Stan 91-091-Iss 9 (2016) 4-3 4.1.6 Def Stan 91-87-Iss 6 (2009) 4-4 4.1.7 DCSEA 134 Ed D 2015 (F-34) / DCSEA 144 Ed D 2015 (F-44) 4-4 4.1.8 TL 9130-0012 Ed E 2012 (F-34) 4-4 4.1.9 STANAG 3747 – Ed11 / AFLP 3747 EdB-v1 2016 4-5 4.2 Concluding Remarks 4-5

Chapter 5 − Additional Considerations for Military Approval of Fuels 5-1 5.1 Background 5-1 5.2 Lack of Consensus on Need for Additional Testing 5-1 5.3 Reasons Why Additional Testing May / May Not Be Required 5-2

Chapter 6 – Recommendations 6-1 6.1 For Military Platform Technical Authority 6-1 6.2 For Original Equipment Manufacturer (OEM) 6-2 6.3 For Follow On AVT Research Task Groups (RTG) 6-3 6.3.1 Impact of Synthetic Jet Fuels on the Single Fuel Policy (SFP) and 6-4 Land Systems 6.3.2 Impact of the Use of Synthetic Fuels on the Navy 6-5

Chapter 7 – References 7-1

Annex A − List of Military Owned or Controlled MPPL A-1

Annex B − Making Conventional Jet Fuel B-1 B.1 Overview of EI/JIG Standard 1530 B-6

Annex C – Summary of Pre-Workshop Survey and Responses C-1

Annex D − Summary of AVT-225 Meeting at IASH 2015 D-1

Annex E − Decision Chart for Military Platform Certification E-1

Annex F − Petroleum Committee Vision on Future Fuels F-1

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List of Figures

Figure Page

Figure 1-1 Carbon Lifecycle for Sustainable Biofuel 1-4 Figure 1-2 Industry Carbon Reduction Goals 1-4 Figure 1-3 Contributions of Measures for Reducing International Aviation Net 1-5 Carbon Dioxide Emission Figure 1-4 Global Share of Aviation Biofuel Initiatives 1-8 Figure 1-5 Commercial Readiness of Synthetic Fuel Flights 1-8 Figure 1-6 Examples of Commercial-Scale Deals 1-9

Figure 2-1 Distribution of Freezing Point in °C in 2013 PQIS Report and in 2-4 Lufthansa Study Figure 2-2 Distribution of Viscosity at -20°C in cSt in 2013 PQIS Report and 2-4 in Lufthansa Study Figure 2-3 Chemical Structures of Typical Biofuels of the First Generation; 2-6 Chemical Structures of Typical Constituents of Fossil Aviation Turbine Fuel

Figure 3-1 Pictorial Overview of the ASTM D4054 Fuel and Additive 3-2 Approval Process Figure 3-2 ASTM D4054 Testing Requirements 3-3

Figure 4-1 References to Synthetic Fuels and ASTM D7566 Approved 4-7 Annexes in Various Fuel Specifications

Figure 6-1 Decision Chart for Military Platform Certification 6-1

Figure A-1 Coverage of the NATO Pipeline Systems A-1

Figure B-1 Stage 1 Processing – Distillation, Which Sets Basic Properties B-2 and Yield Figure B-2 Regional Differences in 2013 Refinery Production B-2 Figure B-3 Examples of Refinery Streams Blended to Make Jet Fuel B-3 Figure B-4 Jet Fuel Blending Options at a Complex Refinery B-4 Figure B-5 International Jet Fuel Quality Assurance Standards from Production B-6 to Airport

Figure E-1 Decision Chart for Military Platform Certification E-1

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List of Tables

Table Page

Table 2-1 Classes of Hydrocarbons Found in Aviation Turbine Fuel and 2-1 Typical Representatives for Each Class

Table 3-1 Approved Jet Fuels and Their Main Characteristics 3-5

Table 4-1 Civil and Military Jet Fuels Classifications 4-1 Table 4-2 References to Synthetic Fuels and ASTM D7566 Approved 4-6 Annexes in Various Fuel Specifications

Table 5-1 Reasons to Support/Not Support Platform Certification with New Fuel 5-2

Table B-1 Typical Considerations for Typical Jet Processing Routes B-4 Table B-2 Kerosene Streams that are Suitable for Jet Fuel Production B-5

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List of Acronyms

AC Aircraft ADU Atmospheric Distillation Unit AFC Aviation Fuels Committee AFLP Allied Fuels Logistics Publication AFQRJOS Aviation Fuel Quality Requirements for Jointly Operated Systems (Leads to “Check List” for Jet A-1 used internationally) AO Antioxidant ASTM A standards development organization, formerly “American Society for Testing and Materials” ATJ-SKA Alcohol To Jet – Synthetic Kerosene with Aromatics ATJ-SPK Alcohol To Jet – Synthetic Paraffinic Kerosene Avcat Aviation carrier turbine fuel AVT Applied Vehicle Technology (Panel) Avtur Aviation turbine fuel

B7 Diesel containing 7% volume biodiesel (usually FAME)

CDU Crude Distillation Unit CEPS Central Europe Pipeline System CGSB Canadian General Standards Board CHCJ Catalytic Hydrothermal Cellulosic Jet CIS Commonwealth of Independent States CTL Coal To Liquids

Def Stan Defence Standard DLA Defense Logistics Agency DLR Deutsches Zentrum für Luft- und Raumfahrt e.V (German Aerospace Centre) DoD Department of Defense (United States)

EASA European Aviation Safety Agency EI Energy Institute

FAA Federal Aviation Administration FAME Fatty Acid Methyl Ester FBP Final Boiling Point FFP Fit For Purpose FSII Fuel System Icing Inhibitor FT Fischer-Tropsch FT-SPK Fischer-Tropsch Synthetic Paraffinic Kerosene

GOST Gosudarstvennyy Standart GRPS Greek Pipeline System

HEFA Hydroprocessed Esters and Fatty Acids HEFA-SPK Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene HFRR High Frequency Reciprocating Rig HRD Hydroprocessed Renewable Diesel HRJ Hydrotreated or Hydroprocessed Renewable Jet HVO Hydrogenated Vegetable Oil

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IBP Initial Boiling Point ICPS Icelandic Pipeline System

JFTOT Jet Fuel Thermal Oxidation Test JIG Joint Inspection Group

LIA Lubricity Improver Additive

MDA Metal Deactivator Additive Merox Mercaptan Oxidation (Proprietary refinery “sweetening” process to convert mercaptans to disulphides) MOD Ministry Of Defence MPPL Multi-Product Pipeline MTCH Military Type Certificate Holder

NATO North Atlantic Treaty Organization NEPS Northern European Pipeline System NIPS Northern Italy Pipeline System NLR Nationaal Lucht- en Ruimtevaartlaboratorium (Netherlands Aerospace Centre) NOPS Norwegian Pipeline System NPS NATO Pipeline System NRC National Research Council Canada

OEM Original Equipment Manufacturer (Usually refers to the engine manufacturer or the aircraft company) POPS Portuguese Pipeline System ppm parts per million PQIS Petroleum Quality Information System

RTG Research Task Group

SDA Static Dissipator Additive SIP Synthetic Isoparaffinic Kerosene SK Synthetic Kerosene SKA Synthetic Kerosene with Aromatics SPD Synthetic Paraffinic Diesel SPK Synthetic Paraffinic Kerosene SPK/A Synthesized Paraffinic Kerosene plus Aromatics SR Straight Run (Primary kerosene product after first stage distillation) SSJF Semi-Synthetic Jet Fuel STANAG Standardization Agreement STO Science and Technology Organization (NATO)

TUPS Turkish Pipeline System

US United States (of America) v/v volume/volume, usually expressed as a percentage

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AVT-225 Membership List

CO-CHAIRS

Prof. Ashwani K. GUPTA Mr. Shaji MANIPURATH* University of Maryland – Mechanical Engineering National Research Council of Canada UNITED STATES CANADA Email: [email protected] Email: [email protected]

MEMBERS

Mr. Daniel BANISZEWSKI Mrs. Pascale DEMOMENT Defense Logistics Agency Energy TOTAL UNITED STATES FRANCE Email: [email protected] Email: [email protected]

∗ Dr. Joanna BAULDREAY* Mr. Fabrice GUIDOTTI* Shell Research Limited Belgian MoD UNITED KINGDOM BELGIUM Email: [email protected] Email: [email protected]

Maj. Tomasz BIALECKI Mr. Peter HOPKINS Air Force Institute of Technology Defence Equipment and Support POLAND UNITED KINGDOM Email: [email protected] Email: [email protected]

Dipl. Ing. Wolfgang BIENENDA Dipl. Ing. Antonios KANAKIS* AIRBUS DS – TEAYP-TL5 National Aerospace Laboratory (NLR) GERMANY NETHERLANDS Email: [email protected] Email: [email protected]

Ir. Patrick BOSMANS** Prof. Dr. Petros KOTSIOPOULOS NATO Support and Procurement Agency / Hellenic Air Force Academy CEPS PO GREECE FRANCE Email: [email protected] Email: [email protected] Dr. Jens Peter ORTNER Mr. Ahmet CELIKYAY WIWEB Ministry of Defence, Undersecretariat for GERMANY Defence Email: [email protected] TURKEY Email: [email protected] Dr. Sebastian SCHEUERMANN* Bundeswehr Research Institute for Materials, Ltcdr. Ilhan COSKUN Fuels and Lubricants Turkish Navy GERMANY TURKEY Email: [email protected] Email: [email protected] Dr. Mickaël SICARD* ONERA FRANCE Email: [email protected] ∗ Contributing Author.

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Prof. Jiri STODOLA Col. ret. Jerzy WALENTYNOWICZ University of Defence in Brno Military University of Technology CZECH REPUBLIC POLAND Email: [email protected] Email: [email protected]

Mr. Alik STONE* Ing. Willem ZIJDERVELD* Dstl Defence Materiel Organisation UNITED KINGDOM NETHERLANDS Email: [email protected] Email: [email protected]

Dip. Eng. Jan VALA Dr. Alexander ZSCHOCKE* TATRA, a.s. Deutsche Lufthansa AG CZECH REPUBLIC GERMANY Email: [email protected] Email: [email protected]

Mr. Philippe VAN EXEM NATO HQ BELGIUM Email: [email protected]

ADDITIONAL CONTRIBUTORS1

Mr. Robert ALLEN Dr. Richard CLARK US Air Force Research Laboratory Shell Global Solutions UNITED STATES UNITED KINGDOM Email: [email protected] Email: [email protected]

Dr. Gurhan ANDAC Mr. Benet CURTIS General Electric Aviation US Air Force Petroleum Office UNITED STATES UNITED STATES Email: [email protected] Email: [email protected]

Mr. Renco BEUNIS Maj. (Ret.) Christian GRAßL SkyNRG RUAG Aerospace Services NETHERLANDS GERMANY Email: [email protected] Email: [email protected]

Mr. Tedd BIDDLE Mr. Bart LEENDERS Pratt & Whitney Neste Oil Netherlands UNITED STATES NETHERLANDS Email: [email protected] Email: [email protected]

2 Mrs. Catherine BOUQUET Mr. Pierre POITRAS Dassault Aviation Canada Department of National Defence FRANCE CANADA Email: [email protected] Email: [email protected]

* Contributing Author. 1 Over the course of its term, the AVT-225 Task Group has had the pleasure of interacting with various stakeholders within the extended “fuels community” who have lent their support through attending one of AVT-225’s meetings or more generally in the provision of inputs or comments. 2 Chairman, NATO Fuels and Lubricants Working Group. x STO-TR-AVT-225

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Mr. Mark RUMIZEN Mr. Brad WALL Federal Aviation Administration Rolls-Royce UNITED STATES UNITED STATES Email: [email protected] Email: [email protected]

Mr. Stanford SETO32 Mr. George WILSON III4 General Electric Aviation3 Southwest Research Institute UNITED STATES UNITED STATES Email: [email protected] Email: [email protected]

Maj. Florian TOMAT Centre d’expertise pétrolière interarmées FRANCE Email: [email protected]

PANEL MENTORS

Dr. Richard CARLIN Dr. Ferdinand TESAR Office of Naval Research Military Technical Institute s.e. UNITED STATES CZECH REPUBLIC Email: [email protected] Email: [email protected]

3 Chairman, ASTM Subcommittee D02.J0 (Aviation Fuels). 4 Chairman, ASTM subcommittee D02.J0.06 (Emerging Turbine Fuels).

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Military User’s Guide for the Certification of Aviation Platforms on Synthetic Jet Fuels (STO-TR-AVT-225)

Executive Summary

Before any alternative jet fuel containing synthetic components may be delivered to a NATO aircraft, it must first be ascertained that the appropriate clearance documents permitting its use have been obtained. Typically, clearances for using the fuel on a particular platform would be provided jointly by the military fuel Technical Authority (TA) and the military platform TA (military type certificate holder, weapon system manager, airworthiness authority, aircraft engineering officer, etc.) in cooperation with Original Equipment Manufacturers (OEMs). However, a tendency has sometimes been noted where OEMs, who are not as well integrated with the ASTM International approval process for synthetic jet fuels, are seeking elaborate testing of ASTM D7566-approved fuels prior to their introduction in their military platforms. This adds significant cost, time and effort for the individual certification of such platforms when the effort may already be redundant.

This user’s guide is intended to assist the platform TA in coming up-to-speed on the subject of synthetic jet fuels, and navigating the question of whether to certify a particular platform with an alternative synthetic jet fuel. This user’s guide is also intended to raise awareness among military OEMs so that they will be more involved in the civil approval process (ASTM D4054) for synthetic fuels meeting the requirements of ASTM D7566 Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons. This user’s guide provides a simple flowchart to guide the platform TA’s decision-making. The decision flowchart’s underlying premise is that the final authority to clear a platform rests with the TA, based on a risk-assessment carried out with all available information on the candidate fuel.

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Guide d’utilisation militaire pour la certification des plateformes d’aviation alimentées par des carburéacteurs de synthèse (STO-TR-AVT-225)

Synthèse

Avant de fournir du carburéacteur alternatif contenant des composants synthétiques à un aéronef de l’OTAN, il est impératif de s’assurer que les documents autorisant son utilisation ont été obtenus. Habituellement, les autorisations d’utilisation du carburant dans une plateforme particulière sont fournies conjointement par l’autorité technique (TA) des carburants militaires et l’autorité technique des plateformes militaires (titulaire du certificat de type militaire, gestionnaire du système d’arme, autorité de navigabilité, responsable de l’ingénierie des aéronefs, etc.) en coopération avec les constructeurs aéronautiques (OEM). Cependant, une tendance se dessine, selon laquelle les OEM, qui ne sont pas aussi bien intégrés dans le processus d’approbation international de l’ASTM pour les carburéacteurs de synthèse, demandent parfois des essais poussés de carburants approuvés selon la norme ASTM D7566 avant leur introduction dans leurs plateformes militaires. Les coûts, le temps et les efforts supplémentaires ainsi consacrés à la certification individuelle de ces plateformes peuvent être redondants.

Le présent guide est conçu pour aider l’autorité technique des plateformes à acquérir un rythme normal au sujet des carburéacteurs de synthèse et à déterminer s’il faut certifier une plateforme donnée avec un carburéacteur de synthèse alternatif. Ce guide est également destiné à sensibiliser les OEM militaires afin qu’ils soient plus impliqués dans le processus d’approbation civil (ASTM D4054) pour les carburants synthétiques satisfaisant aux exigences de l’ASTM D7566, Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons (Spécification normale pour carburéacteur contenant des hydrocarbures de synthèse). Ce guide d’utilisation fournit un organigramme simple pour orienter les décisions de l’autorité technique des plateformes. Le principe sous-tendant l’organigramme décisionnel est que l’autorisation d’une plateforme revient en dernier ressort à l’autorité technique, qui la délivre sur la base d’une évaluation du risque menée avec toutes les informations disponibles au sujet du carburant proposé.

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Chapter 1 − INTRODUCTION AND MOTIVATION

1.1 RESEARCH TASK GROUP AVT-225

1.1.1 Background Factors such as concerns over climate change, the finite nature of oil reserves, and concerns over security of supply from the oil producing regions have triggered a broad effort in the search for new sources and conversion processes for the production of alternative fuels. The increasing availability of such liquid alternative fuels, and their mixing with conventional petroleum distillate fuels, have led to a need for NATO member nations to more closely coordinate to study and (where necessary) mitigate any negative effects of the introduction of such fuel blends on their military vehicles and systems (air, land or naval) as well as operational procedures.

In coordination with the NATO Petroleum Committee (PC), this Technical Group, AVT-225 “Future Technological and Operational Challenges Connected with Application of Synthetic Fuels”, was formed under the Applied Vehicle Technology (AVT) panel of the NATO Science and Technology Organization (STO). This task group, with a three year mandate (January 2014 to December 2016), was a continuation of multiple long-standing fuel-related technical task groups within the NATO STO, as well as the Research and Technology Organization (predecessor organization to the STO). Previous activities of note: • AVT-035: Future Technological and Operational Challenges Associated with the Single Fuel Concept (1999 – 2002): • Main Output: Technical Report TR-066 (2003). • AVT-ET-073: Proposals for Solutions to Problems Related to the Use of F-34 (SFP) and High Sulphur Diesel on Ground Equipment Using Advanced Reduction Emission Technologies (2005 – 2006): • Main Output: Technical Memorandum TM-AVT-ET-073 (2008). • AVT-ET-076: AVT Response to Research and Technology Board Question “NATO Dependency on Oil” (2006): • Main Output: Technical Activity Proposal for follow-on task group AVT-159 (2007). • AVT-159: Impact of Changing Fuel Upon Land, Sea and Air Vehicles (2008 – 2011): • Main Output: Technical Report on the impact of biodiesel blends B10 and B20 on land-based vehicles TR-AVT-159 (2014). • AVT-ET-128: Future Technological and Operational Challenges Connected with Application of Synthetic Fuels (2012): • Main Output: Technical Activity Proposal for the present task group activity AVT-225 (2012).

To support and provide steering direction to the above AVT activities, and since 2007, the NATO PC began producing and updating its “The Petroleum Committee Vision on Future Fuels” which provided a strategic forecast of emergent near-term (10 year), medium-term (10 to 20 years) and long-term (20+ years) petroleum- alternative options. To-date, the PC has produced three versions of this document (2007, 2010 and 2014). The latest version (2014) is reproduced in Annex A. Please note that at the time of finalising the present guide (March 2017), a newer version to the “Vision on Future Fuels” was in the process of being approved.

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1.1.2 Mandate and Progress The starting mandate for AVT-225 was broad in scope (by intention), with the understanding that the scope would be further refined to produce an useful output factoring in the preeminent challenge and concern as emergent out of consensus between the group representatives. As such, the original mandate of the activity was “to evaluate the opportunities and threats posed by synthetic fuels and their blends on NATO vehicles and systems (air, land or naval)”.

During its three year mandate, AVT-225 officially met two times per year (usually in conjunction with the AVT Panel Business Meetings in the spring and fall) with the following main outcomes: • Spring 2014 in Copenhagen, Denmark: A revised Petroleum Committee Vision on Future Fuels (Edition 2014) was presented by the NATO PC representative and a strategy was formed to liaise with additional external experts formulated. • Fall 2014 in Brussels, Belgium: Workshop held with 27 attendees, including 8 invited guest speakers, to understand the emergent issues and opportunities for synthetic fuels in military platforms. Consensus formed on better need for coordination and acceleration of certification of military platforms. • Spring 2015 in Rzeszów, Poland: Further refining of the AVT-225 focus, and value proposition to improve coordination, and acceleration of certification of military aviation platforms with synthetic jet fuels. Planning for a workshop with Original Equipment Manufacturer (OEM) representatives, ASTM representatives involved in the development of synthetic jet fuel standards, and other stakeholders. • Fall 2015 in Charleston, USA: Workshop meetings held on the sideline of the IASH 2015 “International Symposium on Stability, Handling and Use of Liquid Fuels”. Consensus emerged for a “military user guide” to facilitate quicker certification of aircraft platforms on civil-approved synthetic fuels as the final deliverable for the AVT-225 group. • Spring 2016 in Tallinn, Estonia: Final report planning and tasking. • Fall 2016 in Ávila, Spain: Final report review and integration.

1.1.3 Present Focus and Objective In its initial meetings (in spring 2014, fall 2014 and spring 2015), the AVT-225 team had identified a need to promote a more rapid and streamlined adoption of approved fuels by NATO member nations. It had also identified potential gaps that need to be bridged for the military to more readily accept civil-approved alternative aviation turbine fuels (according to ASTM D4054 and D7566) in its platforms. In addition, it also emerged that the lagging military acceptance was also found to be creating barriers for approved fuels wanting to use common fuel distribution logistics for civil applications, particularly in Western Europe. This is covered in greater detail in Section 1.4 of this report.

Consequently, during the fall 2015 meeting, a consensus was built that AVT-225 should produce a military- centric “user’s guide” to raise awareness among all the different stakeholders (in the military, as well as the OEM community) to facilitate a quicker certification of aircraft platforms on civil-approved synthetic fuels.

The objective of this user’s guide is three-fold: • Before any fuel containing synthetic components may be delivered to a NATO aircraft, it must first be ascertained that the appropriate clearance document(s) permitting its use have been obtained. Typically, clearances would be provided by the Technical Authority (TA) for the fuel in concert with

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the Military Type Certificate Holder (MTCH) weapon system manager, airworthiness authority and/or aircraft engineering officer – collectively referred to here as the platform’s Technical Authority (TA), who is the risk “owner” for the platform. This report is intended to assist the platform TA in coming up- to-speed on the subject of alternative jet fuels, and navigating the question of certifying or clearing an alternative synthetic fuel for a particular platform. • This user’s guide is also intended to raise awareness among military OEMs so that they will be more involved in the civil approval process (ASTM D4054) for synthetic components meeting the requirements of ASTM D7566 Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons. Fuel streams approved via this route are allowed by the main international civil fuel specifications as well as military fuel specifications, and consequently may find their way to the military platform. This is examined in greater detail in Chapter 4. • Lastly, but not least, the issue of whether a fuel approved through the civil ASTM D4054 process meets the criteria for military applications is also not completely resolved. The present assessment of AVT-225 is that there are differing levels of readiness to accept an approved synthetic fuel by the OEMs, and the situation also changes from platform to platform. In several instances, costly and time- consuming certification tests have been recommended by the OEMs, which have served to inhibit adoption of synthetic fuels. This report is also intended to inform the wider “fuels community”, spearheading the development, certification and adoption of synthetic jet fuels in the civil aerospace markets, of the benefits of aligning the civil and military approval processes such that military non- adoption does not become a barrier to the civil markets due to shared fuel distribution infrastructure in many NATO nations.

1.2 MOTIVATION FOR CERTIFICATION OF PLATFORMS FOR SYNTHETIC FUELS Since the first synthetic jet fuelled commercial flight in 1999 and the first synthetic bio-derived jet (or “biojet”) fuelled commercial flight in 2008 (20% blend in one of its engines), there has been a great amount of progress by the industry and partners. Approval through the global fuel standards agency ASTM allowed expansion of the use of synthetic fuels and it may be estimated that more than 5000 commercial flights on these synthetic fuels have flown since 2011. This culminated in the approval of synthetic jet fuel blends as part of the ASTM and Def Stan fuel standards. [1], [2], [3]

Synthetic fuels are only beginning to enter the jet fuel market. These fuels are entering the market, driven by factors such as oil price spikes and the need for increased energy security. However, many of the synthetic fuels that are currently being supplied have been criticized for their adverse impacts on the natural environment, food security, and land use. Depending on the feedstock and production process, sustainable synthetic fuels can be produced without negatively impacting the environment.

Bio-derived synthetic fuel (or “biofuel”) presents an elegant solution to reducing the growth of carbon dioxide emissions. Ideally it presents an almost closed loop system. Plants and algae absorb atmospheric carbon dioxide during photosynthesis for growth and metabolism. Later the biomass is harvested and sent to a biofuel refinery where it is processed into aviation biofuel and other products. The resulting fuel meets the requirements for jet fuel. A jet engine operating solely from sustainable biojet fuel only releases the carbon absorbed by the feedstock plants, which results in better lifecycle environmental performance.

Similarly, sustainable biofuel can also be made from residual products such as waste cooking oil, industrial by- products, or even municipal solid waste.

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Figure 1-1: Carbon Lifecycle for Sustainable Biofuel [4], [5].

There are several reasons for interest in synthetic jet fuel. 1) Synthetic jet fuels are just as safe as the regular fuel we use to power aircrafts. The fuel meets the same stringent international fuel specifications as conventional jet fuel. Synthetic jet fuels must consist entirely of hydrocarbon compounds that are already found in petroleum jet fuel. In other words, synthetic jet must be a drop-in fuel that can be used by itself or as a blend. Drop-in fuels share the same properties as (or even better properties than) the jet fuel we use today, and so can simply be blended with the current fuel supply as they become available. [3] 2) Aviation synthetic fuels can be tailored to produce superior properties in several respects: thermal stability (better heat exchange potential), freezing point (higher altitudes), flash point (handling safety), etc. 3) The approval process for new formulations of synthetic jet fuel is very involved, due to the range of conditions under which jet fuel must perform. Note: Downstream of the blending, the presence of synthetic components in the distribution chain does not necessarily have to be mentioned on the fuel quality certificate. 4) Sustainable synthetic aviation fuels will play an important role in meeting the industry’s ambitious carbon emissions reduction goals (see Figure 1-2).

Figure 1-2: Industry Carbon Reduction Goals [5].

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All stakeholders need to play an active role in materializing the aviation sectors environmental goals of

carbon neutral growth from 2020 and halving CO2 emissions by 2050, relative to 2005. [5], [6], [7]

Unlike the ground transport sector, which can use electric energy from batteries or fuel cells, aviation needs new liquid fuels compatible with existing systems. Sustainable synthetic aviation jet fuels (currently, mostly biojet fuels), have been identified as one of the key elements in helping achieve these goals. They are the only low-carbon fuels available for aviation in the short to mid-term. Electric commercial aircraft are unlikely before 2040 and will be limited to short-range flights only [3].

Operational improvements and new aircraft technology will not be sufficient to reach the goals. It has been demonstrated that synthetic jet fuels can have significantly lower carbon emissions over their lifecycle compared to fossil fuel sources (up to 80%) [3]. Sustainable aviation synthetic fuel will decrease carbon emissions and support the continued growth of aviation. [2], [5]

Figure 1-3: Contributions of Measures for Reducing International Aviation Net Carbon Dioxide Emissions [5].

5) An Alliance of 29 nations can only work effectively together in joint operations if provisions are in place to ensure smooth cooperation. NATO has been striving for the ability of NATO forces to work together since the Alliance was founded in 1949. Interoperability has become even more important since the Alliance began mounting out-of-area operations in the early 1990s. NATO’s interoperability requirement between allies could be jeopardized if some of the allies were to provide synthetic jet fuel during operations for which not all platforms are cleared. 6) Energy security is a military requirement. Synthetic fuels can incrementally secure the supply of energy. This will allow the geographic diversification of production. Import of fuels can be subject to disruption because of regional or international conflicts or even natural disasters.

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Sustainable synthetic jet fuels allow the reduction of carbon footprints, ease the dependence on fossil fuels and enjoy benefits from increased energy supply diversification.

Many of the technical hurdles facing aviation in its move towards sustainable aviation fuels have been overcome. Now, commercialization and scaling up of the supply of synthetic aviation fuels is the most important task. But airlines and the rest of the industry cannot do it alone – political support and financial investment will have to come from a number of stakeholders, which includes the military. Military distribution networks shared for civil use can have a tremendous impact on airports and synthetic jet fuel producers if the military lags behind in recognizing and accepting synthetic jet fuels.

1.3 CURRENT MARKET READINESS LEVELS FOR SYNTHETIC FUELS There are essentially two kinds of synthetic kerosene: those of fossil origin and bio kerosene. The first approval of synthetic fuel by ASTM in 2009 [8] was based on data for fuel of fossil origin (Fischer-Tropsch kerosene produced from coal by Sasol in South Africa, and from natural gas in the United States and Malaysia), and the overwhelming majority of synthetic kerosene produced is still from fossil feedstock.

The largest facility producing aviation kerosene is currently the Shell-operated Pearl Fischer-Tropsch (FT) plant in Qatar, which uses natural gas as a feedstock. [9] The finished Jet A-1, made by blending the FT kerosene with a conventional Jet A-1, is traded on the open market. In addition to local use, this fuel is also available for export, and thus may potentially enter the fuel supply of NATO partners, although most of the fuel is believed to stay within the region. Another plant producing synthetic aviation kerosene from fossil sources is the SASOL coal-to-liquid plant in South Africa, but this is understood only to produce for local use. Fuel from the South African plant is unlikely to enter the fuel market of a NATO partner, but has been supplied to Johannesburg airport since 1999, and may be encountered by aircraft visiting locally. In the extensive experience with using these synthetic fuels, no adverse effects have so far been encountered. In 2015, ASTM approved the inclusion of coal-derived aromatics blended with the Sasol FT kerosene, but there is as yet no information on the extent to which this product is used. [10]

The reason for the operation of these plants is economics, with the prices of the feedstock (coal, natural gas) below those of liquid fuels. Bio kerosene, on the other hand, is considerably more expensive than fossil kerosene, and hence is used for environmental and political reasons, with the high cost of the fuel restricting wider use.

The Fischer-Tropsch process for the conversion of coal or natural gas can, in principle, also be used for the conversion of biomass, but so far this has not been put into practice at relevant scale due to the difficulties of converting the biomass into a sufficiently clean gas. [11] However, several other bio kerosene production pathways are being used, and are approved by ASTM, of which the HEFA (synthesized paraffinic kerosene produced from hydroprocessed esters and fatty acids) pathway approved in 2011 is currently the most important one.

Even for HEFA, produced volumes are currently just in the thousands of tons. Two other pathways SIP (Synthesized Iso-Paraffins from hydroprocessed fermented sugars) and ATJ (Alcohol to Jet) have only been approved in 2014 [12] and 2016 [13], with 10 and 30 % volume blend limits, respectively, and produced volumes are much less than for HEFA.

However, these fuels are often produced in NATO member countries, and increasingly enter the common infrastructure at airports. For instance, Oslo airport has been the first where bio kerosene enters the hydrant

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In addition to those described above, various other production pathways are currently undergoing the ASTM approval process, and are expected to be approved in the next couple of years. Of these, two may potentially affect bio kerosene use in a major way. One is the “HEFA+” initiative championed by Boeing, which involves the addition of HEFA road diesel in small percentages. This promises to bring down the cost of bio kerosene to that of bio road diesel, and make bio kerosene blend stock available without need for investment in dedicated production capacity. [16]

The second is co-processing, where vegetable oils are mixed with crude oil as feedstock for a conventional refinery. The primary intention is to use this as a low cost way of producing road fuels with a bio component, but some of the vegetable oil molecules would inevitably also wind up in the kerosene produced by the refinery. This pathway could potentially impact large volumes of kerosene. [17]

Biofuel activities are currently growing strongly. For instance, the Lufthansa Group’s preliminary calculations indicate that in 2016 they operated some 2000 flights from Oslo with a biofuel component, although this is on a mass balance basis. As the supply is through a hydrant system, it is unknown in whose aircraft the physical bio kerosene ended up. ICAO estimated in mid-2016 that by the end of 2016 the total number of commercial flights having used alternative kerosene would exceed 5500. [18] However, this is still a tiny fraction of the millions of commercial flights each year.

The future growth of bio kerosene will depend on political developments, as the use of bio kerosene is currently not economical. Research and development in this field is already well supported by governments, and some biofuel support systems – like the US RIN system – can also be used to support bio kerosene. Unlike for road fuel there are currently no biofuel mandates in place for aviation, but there are political initiatives to introduce such mandates. [18], [19]. In particular, Indonesia has announced the intention to create mandates, although these will have to be internationally coordinated, as aviation is an international business. [20] Should such bio kerosene mandates be introduced, this may lead to significant amounts of bio kerosene entering the market in a short time. In addition, the recent ICAO resolution introducing market-based measures to reduce net CO2 emissions from aviation explicitly foresees bio kerosene use. [21]

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Figure 1-4: Global Share of Aviation Biofuel Initiatives [5].

Figure 1-5: Commercial Readiness of Synthetic Fuel Flights [22].

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Figure 1-6: Examples of Commercial-Scale Deals (Source: Top [22] and Bottom [23]).

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1.4 IMPACT OF MILITARY’S LAGGING ADOPTION OF SYNTHETIC FUELS Industry and its partners have made significant progress; however, restrictions associated with use of synthetic fuels by the military have an implication on shared distribution networks on civil uses, like some of the NATO Pipeline Systems (NPS). Pipelines are available only in limited quantity and have a lot of advantages compared to other transport means. For example, the Central Europe Pipeline System (CEPS) is the largest of the NATO pipeline systems crossing five nations: Belgium, France, The Netherlands, Germany and Luxembourg. CEPS provides an important NATO capability, not only in terms of its support to military operations but also for energy security. A list of all NPS has been made available in Annex A.

The CEPS system is also available to commercial clients for several operational and economic reasons like the reduction of the yearly financial contributions of the CEPS member nations for the maintenance and its compliance with international regulations and requirements. CEPS uses a jet fuel banking system for all its clients, civil or military. Many major international airports receive some or most of their jet fuel from pipeline delivery systems including these NATO systems, with CEPS particularly relevant for deliveries to those in North West Europe such as Schiphol, Frankfurt, Brussels and Zurich. Like a bank with different distributing machines (e.g., ATM) from where you can get money bills that are not the same as the ones you have put on your account but still recognized as valid cash, at CEPS you will not get the same molecules from an off-take point as the one you have entered at an ingress point. This system gives a lot of operational flexibility: once a client has introduced fuel into the CEPS network, the delivery of the corresponding can be made immediately at any point.

The STANAG/AFLP 3747 “Guide specifications (minimum quality standards) for aviation turbine fuels (F-24, F-27, F-34, F-35, F-37, F-40 and F-44) – Ed B version 1”, approved by the member nations under the Petroleum Committee of NATO, stipulates that the use of synthetic jet fuel must be authorized by the military technical airworthiness authority of the involved country. Hence, unless there is an approval of all CEPS member nations, synthetic jet fuel cannot be part of the banking system. Only a few allies have approved the use of these synthetic blends. Therefore synthetic jet fuel could only be transported in CEPS from point-to-point which would still jeopardize the banking system in parts where the lines are already working at full capacity. The CEPS’ banking system is absolutely necessary to the activity of the network. So, in a co-shared supply chain care needs to be taken to understand the military logistic requirements which sometimes can be more restrictive than civil jet fuel specs. This limitation is still one of the cost drivers for synthetic jet fuel at airports.

On the other hand, military aircraft do refuel on airfields that could contain synthetic components since these are approved and recognized by the international fuel specifications. Downstream of the blending, the presence of synthetic components does not even have to be mentioned on the fuel quality certificate, although it may have been mentioned on the original (Refinery) Certificate of Quality. The risk is even higher as about 60% of Europe’s jet fuel is imported. Additionally, the detection at a laboratory of these synthetic fuel components in a distribution chain is as good as impossible since they have in fact the same type of molecules as conventional jet fuel.

There is also scope for military aircraft taking part in joint operations getting synthetic components during refuelling if the Ally providing the fuel has approved the use of it and fully certified its platforms to use the approved fuel. US Air Force Energy Plan 2010 stipulates that a major part of the domestic aviation fuel has to be a synthetic blend. The US DoD operational energy strategy wants more options and less risk, meaning expanding and securing the supply of energy to military operations which implies an alternative energy policy. Future joint operations could become a problem due to logistic incompatibilities. Non-alignment in fuel supply between allies will cause interoperability problems during large scale operations. It is urgent for the allies to take into account the evolution of the fuel products and accept the integration of the synthetic jet fuel as having acceptable quality for military aviation.

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As mentioned earlier, synthetic fuels can be engineered to have excellent long term storage capability, better thermal stability than conventional fuels, lower freezing points, and can be safer to handle due to higher flash points. So from a logistic point of view, acceptance by all member nations of jet fuel containing synthetic blend components is of significant importance because of: • Security of supply of high quality jet fuel for the military by aligning military and civil jet fuel specifications and jet fuel qualities. • Maintaining the necessary interoperability and interchangeability through NATO member nations’ collective responsibility for logistic support.

1.5 ORGANIZATION OF REPORT The following provides a brief outline of the remainder of this report. While the document can be read sequentially, the reader can also skip ahead to relevant sections of interest. This user’s guide is not intended to be an exhaustive reference work, but rather provides a concise introduction to the issues and topics as a jumping point for a more in-depth investigation, as required.

Chapter 2 “JET FUEL 101” provides a fundamental overview of the composition and properties of fossil-based kerosene, as well as how it differs from its drop-in synthetic kerosene counterparts. An introduction to the various civil and military aviation fuel specifications are also provided here.

Chapter 3 “JET FUEL APPROVAL PROCESSES” then describes present civil and military fuel approval processes, which is then followed by an examination of the existing linkages between civil and military fuel specifications in Chapter 4 “LINKAGES BETWEEN CIVIL AND MILITARY SPECIFICATIONS”.

A high-level discussion of the potential additional testing requirements for military applications is then introduced in Chapter 5 “ADDITIONAL CONSIDERATIONS FOR MILITARY APPROVAL OF FUELS”.

The report then concludes with recommendations to the military platform Technical Authority, military OEM representatives, as well as recommendations for future work to be done by subsequent AVT Research Task Groups (RTG).

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Chapter 2 − JET FUEL 101

2.1 COMPOSITION AND PROPERTIES OF FOSSIL-BASED KEROSENE Crude oil, as drilled from the ground, is a natural product with a quite heterogeneous composition. After being processed in a refinery, the resulting product is more defined, yet it still contains hundreds of chemical compounds. Moreover, there are different production processes by which crude oil can be converted into kerosene. Depending on the refinery, these processes can result in differences in the final products, even though they all meet the minimum compositional and performance requirements in the specifications. In addition, some fractions of the distillation cut can either go into kerosene or into diesel, depending on the market prices of the day and on the season. Thus, even for a given refinery and given crude the actual kerosene produced can vary from batch to batch. Accordingly, although all kerosene has to meet the specification, there is considerable heterogeneity in the composition and the properties of kerosene produced.

2.1.1 Composition of Kerosene [24], [25] With the exception of small amounts of sulphur, oxygen or nitrogen (heteroatomic) containing species, kerosene only consists of hydrocarbons. The variation is in the percentage of the various classes of hydrocarbons, and in the structures and sizes of the molecules within each class.

The classes of hydrocarbons in kerosene are n- and iso-alkanes, cyclo-alkanes and aromatic compounds (Table 2-1). The specification only limits the total aromatics content and, directly or indirectly, a subclass of the diaromatic compounds, the naphthalenes.

Table 2-1: Classes of Hydrocarbons Found in Aviation Turbine Fuel and Typical Representatives for Each Class.

N-alkanes

Iso-alkanes

Cyclo-alkanes

Monoaromatic compounds

Monoaromatic naphthenic compounds

Diaromatic compounds

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The classes of hydrocarbons in kerosene may be described as such: • N-alkanes: These are straight chain molecules, whose composition conforms to equation:

• Iso-alkanes: These are chain molecules, whose𝐶𝐶𝑛𝑛𝐻𝐻 composition2𝑛𝑛+2 also conforms to equation:

but unlike n-alkanes these molecules are𝐶𝐶 𝑛𝑛branched,𝐻𝐻2𝑛𝑛+2 i.e. there are two or more chains, where the combined number of C molecules is n. • Cyclo-alkanes: These are saturated ring molecules with the chemical formula:

They are also known as naphthenes (not to 𝐶𝐶be𝑛𝑛𝐻𝐻 confused2𝑛𝑛 with naphthalenes). A naphthenic material is one with above average cyclo-alkane content.

• Aromatic compounds: These are unsaturated ring molecules with the chemical composition:

𝐶𝐶𝑛𝑛𝐻𝐻2𝑛𝑛−6 In all these equations, the carbon number, n, is typically in the range between 9 and 14, and can go up to 18.

N- and iso-alkanes have the largest hydrogen-to-carbon-ratio and hence offer the highest net heat of combustion at the lowest density, and burn the cleanest. Iso-alkanes are also important to give kerosene good cold-flow properties.

Cyclo-alkanes have a slightly lower hydrogen-to-carbon ratio than alkanes, which results in a reduced heating value. Their density is higher than that of n- and iso-alkanes.

Aromatic compounds have the lowest hydrogen-to-carbon ratio, resulting in the lowest heating value. They feature the highest densities among the fuel constituents. When burned, aromatic compounds cause soot and smoke formation. However, because of their chemical properties, they are the hydrocarbon class that interact most with materials like certain elastomers (e.g. seals). This is a desirable characteristic as it causes seals to swell and thus preserves their tightness which otherwise would be eroded as plasticisers are extracted by the fuel during use. The presence of aromatic compounds is therefore desired in kerosene. However, due to their unfavourable combustion properties, their amount is limited to 25%1 in most fuel specifications. For one particular class of diaromatic compounds, naphthalenes, the corresponding limit is 3% (applicable only if the smoke point limit is 25 mm), as these have a particularly strong tendency to cause soot. [26]

Another type of hydrocarbon present in kerosene is an alkene. These unsaturated molecules originate from cracking processes within the refinery. Although they are hydrocarbons, they are undesirable in kerosene, as they are often unstable and hence have an adverse effect on the storage properties of kerosene. Their presence in kerosene is in practice limited to a maximum of about 1% by the need to pass the JFTOT thermal stability test (ASTM D3442).

1 Measured by ASTM D1319 / IP 156. If ASTM D6379 / IP 436 is used, the corresponding value is 26.5%.

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Among the heteroatomic materials in jet (those containing not just carbon and hydrogen but also oxygen, sulphur or nitrogen) the main one by volume is sulphur. Most jet fuels have a few parts per million (ppm) at most of nitrogen but the maximum permitted amount of sulphur in kerosene is 3,000 ppm (0.3%); higher percentages might cause operational problems, like corrosion or thermo-oxidatively formed deposits in the aircraft engines. The far stricter limitations imposed in the developed world on other fuels for environmental reasons do not apply to aviation kerosene. Kerosene with a sulphur content of some 3,000 ppm may be produced even in countries that otherwise limit sulphur content in ground fuel to 10 ppm or such values. However, in practice a refinery producing low sulphur road diesel will often find it most efficient to produce the kerosene as part of the same production process, and hence will also produce low-sulphur kerosene. The range of sulphur content actually found in kerosene therefore runs virtually the entire gamut of possibilities, from single digit ppm values to close to the permitted maximum of 3,000 ppm.

Other components, like metals, are typically largely removed by the refining process, and are only present in trace amounts (below 1 ppm) in aviation kerosene. Metals can be picked up in transport and storage, so there are industry recommendations to limit the scope for this to occur.

2.1.2 Properties of Aviation Kerosene The target properties of aviation kerosene are defined in the respective specifications. Internationally the most important of these specifications are those for Jet A-1 and for F-34, its military equivalent. Within the United States, the civil kerosene specification is Jet A, which apart from a higher freezing point is basically identical to that for Jet A-1. The US requirements for additives, total acidity and cleanliness are currently less severe than seen for Jet A-1 made to Def Stan 91-091 or “Check List”. Since 2015, the military equivalent to Jet A, F-24, is also the standard fuel for military use within the US.

Although the specifications define target properties, they typically specify ranges rather than exact numerical values, either by explicitly prescribing both an upper and a lower bound, or by only defining either a minimum or a maximum. An example for the first is density, which in the case of Jet A and Jet A-1 is required by ASTM D1655 to be between 775 and 840 kg/m3. An example for the second kind is the freezing point, which for Jet A may be no higher than -40°C, and for Jet A-1 no higher than -47°C, but for which there is no lower limit. [26]

Within the range defined by the specification, there is much variety corresponding to the heterogeneous nature of kerosene already discussed. An important source for data on the actual distribution of aviation kerosene properties is the Petroleum Quality Information System (PQIS) report [27], which is annually published by the US Defense Logistics Agency (DLA) and is based on information on every batch of kerosene purchased by the DLA for the US armed forces in the year covered in the report. In addition to this report, there is an analysis that was performed by Lufthansa on German data, and an annual report on UK kerosene properties is now being produced again. The Lufthansa study covered all kerosene delivered to German airports in the course of one year, but was only produced once. [24] The UK survey covers all Jet A-1 fuel batched in the UK and, with 60% of the fuel being imported, also covers internationally available Jet A-1. [28]

In most cases, data on kerosene property distribution are very similar for all three sources, indicating that the annual PQIS report, which is available from the DLA, can also be used for kerosene outside the United States. This is, however, not the case for freezing point data, where US kerosene shows a tendency to markedly higher freezing points than is the case elsewhere. This is illustrated in Figure 2-1, which compares data for 2013 US government purchases of JP-8 to the Lufthansa study data. UK freezing point data is not shown, but is also lower than the US data. This higher freezing point for JP-8 reflects that the US refining industry, which has gasoline as its main fuel, is predominantly geared to the production of Jet A fuel, with its higher freezing point.

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Figure 2-1: Distribution of Freezing Point in °C in 2013 PQIS Report and in Lufthansa Study [24].

A property related to the freezing point is viscosity at -20°C. Unsurprisingly, there is also considerable difference between US and German distributions, with US kerosene having markedly worse viscosity than the German kerosene (Figure 2-2).

Figure 2-2: Distribution of Viscosity at -20°C in cSt in 2013 PQIS Report and in Lufthansa Study [24].

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2.1.3 How is it Refined? The reader is referred to Annex B for a more in-depth exposition on the basics of conventional refining practices used to make kerosene streams that can be blended to make jet fuels. The processing steps used will vary with the crudes that the refinery takes, and this will affect some of the kerosene properties. Just as importantly, kerosene is the “fuel in the middle”, so its availability and properties (even its grade) are very much dependent on the demand for gasoline and diesel products. The USA, which has a gasoline economy, favours the production of Jet A while much of the rest of the world, and EU in particular, are diesel economies and Jet A-1 is dominant grade of jet fuel produced.

Variants on some of the refinery processes are also used in the production of synthetic kerosenes. Again the availability of the synthetic kerosene streams is impacted by the demand for the synthetic gasoline or diesel streams, more particularly the latter.

2.2 COMPOSITION AND PROPERTIES OF DROP-IN SYNTHETIC KEROSENE Two kinds of properties need to be distinguished: the properties of the synthetic fuels themselves, and the property of a blend of drop-in fuels with fossil fuel. The requirement for neat synthetic components for jet is that they must only contain molecules that are also present in conventional kerosene (essentially n-alkanes, iso-alkanes, cyclo-alkanes and aromatic compounds). However, there is no requirement that the synthetic fuel must contain all these compounds, and as a matter of fact four out of the five currently approved synthetic kerosenes largely consist of n- and/or iso-alkanes, although in some cases small percentages of cyclo-alkanes and aromatic compounds may be present. In the extreme case, that of synthesized iso-paraffins produced from hydroprocessed fermented sugars (SIP), the fuel only consists of a mixture of C15 iso-alkanes. The properties of the synthetic fuels themselves therefore are not identical to those of conventional kerosene, although they are similar. The synthetic fuels on their own therefore typically would not meet the specification for Jet A / Jet A-1 (ASTM D1655). In particular, their density is lower due to the lack of cyclo-alkanes and aromatic compounds, and depending on the fuel individual other properties also will not be met – for example, SIP fuel on its own has poor low temperature viscosity. Only one approved synthetic fuel (FT kerosene to which aromatic compounds from a separate production process have been added) meets the kerosene specification on its own.

However, neat synthetic fuels are currently not permitted to be used as aviation fuels. Rather, it is permitted to blend them with conventional aviation kerosene, and use the blend as an aviation fuel. The conventional fuel used for blending, and the blend percentage, must be selected such that the resulting blend fully complies with the properties stipulated in the ASTM D1655, Def Stan 91-091 or local specification. This requirement for the blend is covered in a separate specification (ASTM D7566). This specification also defines additional conditions that must be met, like a minimum content of aromatic compounds, a maximum viscosity at -40°C, and minimum gradients for the distillation curves. These are factors which experience has shown not to be an issue for conventional kerosene, but where the new synthetic fuels might lead to blends outside the experience base.

More generally, the certification work of ASTM is geared to ensure that a production process will only be approved for aviation use if a blend with conventional kerosene meeting the specification will be within the experience base for kerosene, not only with regard to the property parameters explicitly defined in the specification, but also in all other relevant respects. For practical purposes, an ASTM D7566 approved blend can therefore be regarded as being indistinguishable from conventional kerosene. The whole approval process is set up so that once made to ASTM D7566 the finished jet fuel can be stored, distributed and sold as Jet A or Jet A-1 according to ASTM D1655, DEF STAN 91-91 or similar specifications. The “drop-in” nature of the fuel means

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2.3 NOT ALL BIOFUELS ARE SUITABLE AS JET FUELS Biofuels such as alcohols (ethanol), vegetable oils (esters of glycerine and fatty acids, so called triglycerides) or biodiesel (fatty acid methyl ester) are not under consideration for aviation applications. Figure 2-3 (left) shows the chemical structures of these most common representatives of first generation biofuels in comparison with typical fossil fuel constituents (n- and iso-alkanes, cyclo-alkanes and aromatic compounds: right).

Figure 2-3: Chemical Structures of Typical Biofuels of the First Generation (Left); Chemical Structures of Typical Constituents of Fossil Aviation Turbine Fuel (Right).

From comparing the chemical structures, it is already obvious that first generation biofuels are chemically different from typical jet fuel constituents. Alcohols and esters are polar compounds, which change the physical and chemical properties of the fossil fuel with which they are blended. Their polar character can, for example, negatively affect material compatibility of the fuel causing damage of tank coatings and sealants. Furthermore, they increase the fuel’s affinity towards water, usually leading to increased contents of water, which in a fuel is a prerequisite for growth of microorganisms like bacteria and fungi. Particularly conspicuous examples for this are found in the widespread problems with microbiological contamination of B7 diesel fuel (biodiesel content up to 7% v/v).

In addition, these compounds typically contain oxygen. The energy density of first generation biofuels is therefore well below that of fossil kerosene, and would adversely affect the range achievable with a given fuel volume. First generation biofuels also typically have freezing points well above what is required for aviation. Unsaturated compounds like fatty acids in triglycerides and biodiesel also are prone to oxidation and therefore lower the storage stability of the fuel. Premature oxidation of the fuel might lead to severe quality defects, like the formation of sediments or deposits in the fuel system.

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All these negative effects of first generation biofuels on fuel quality disqualify them for the use as blend components for aviation fuels. Against the background of safety in aviation, adequate fuel quality is of high priority and deliberate worsening of quality through addition of first generation biofuels cannot be tolerated.

2.4 WHAT ARE JET FUEL SPECIFICATIONS? Jet fuels are specialized products that are manufactured according to very tightly controlled specifications. These specifications are in place and relied upon to control the performance and properties.

Two organizations have a lead role in maintaining specifications for civilian jet fuel: ASTM International, a standards development organization, and the United Kingdom Ministry Of Defence (MOD) Aviation Fuels Committee (AFC). The specifications issued by these two organizations are very similar but not identical. [29], [30]

Defence organizations in many countries maintain separate specifications for jet fuel for military use. The reasons for separate specifications include the operational and logistical differences between the military and civilian systems and the additional demands high-performance jet fighter engines place on the fuel.

The following sub-sections provide a summary of the different civil and military specifications for jet fuels. The reader is also referred to Chapter 4 for a more detailed look at the linkages between the two, particularly with regards to references to synthetic component allowances.

2.4.1 Civil Specifications for Aviation Fuels2 The kerosene type fuels used in civil aviation nowadays are mainly Jet A-1 and Jet A. The latter has a higher freezing point (maximum minus 40°C instead of maximum minus 47°C) and is available only in North America: • Jet A-1: A kerosene grade fuel suitable for most turbine engined aircraft. It has a flash point minimum of 38°C and a freeze point maximum of -47°C. The main specifications for Jet A-1 grade (see below) are the UK specification Def Stan 91-091 (Jet A-1) [31], and the ASTM specification D1655 (Jet A-1) [32]. The current versions of these specifications are Def Stan 91-091 Issue 9 [33] and D1655-16c [34], respectively. • Jet A: A kerosene grade fuel, normally only available in the US. It has the same flash point requirement as Jet A-1 but a higher freeze point maximum (-40°C). It is supplied against the ASTM D1655 (Jet A) specification. • Jet B: A distillate covering the naphtha and kerosene fractions. It can be used as an alternative to Jet A- 1 but because it is more difficult to handle (higher flammability), there is only significant demand in very cold climates where cold weather performance is important. Jet B has a freezing point of -50°C (-58°C for the military equivalent, F-40) and does not usually contain Fuel System Icing Inhibitor (FSII). ASTM has a specification ASTM D6615-15a (2015) for Jet B, but in Canada it is supplied against the Canadian specification CGSB 3.23-2012. • TS-1: The main jet fuel grade available in Russian and CIS states. It is a kerosene type fuel with slightly higher volatility (flash point is 28°C minimum) and lower freeze point (< -50°C) compared to Jet A-1. The Russian specification is the GOST 10227-Edition 2013.

2 Reference is made to the edition of the specifications current at 1 September 2016.

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• Other National Civil Jet Fuel Specifications: There are many individual national specifications. Typically, these are based on the US, UK or former Soviet specifications with minor differences, usually reflecting that they have not caught up with ASTM and Def Stan changes. There are increasing moves to harmonize the small differences between the ASTM and Def Stan specifications. This process of harmonization is also in progress with many national specifications.

Remarks: • The basic civil jet fuel specification used in the United States is ASTM D1655, which defines the requirements for two grades of fuel: • Jet A, a kerosene type fuel having a maximum freeze point of -40°C. • Jet A-1, a kerosene type fuel, identical with Jet A, but with a maximum freeze point of -47°C. • The military jet fuel specification Def Stan 91-091 is also the standard UK civil jet fuel. It defines the requirements for a kerosene type fuel (Jet A-1 grade) having a maximum freeze point of -47°C. • Jet A-1 according to the Def Stan 91-091 specification is very similar to Jet A-1 defined by the ASTM D1655, except for a small number of areas where Def Stan 91-091 is more stringent. • Russian and CIS kerosene type jet fuels are covered by a wide range of specifications reflecting different crude sources and processing treatments used. The grade designation is T-1 to T-8, TS-1 or RT. The grades are covered either by a state standard (GOST) number, or a technical condition (TU) number. The limiting property values, detailed fuel composition and test methods differ quite considerably in some cases from the Western equivalents. The principle grade available in Russia is TS-1. The main differences in characteristics are that Russian and CIS fuels have a low freeze point (equivalent to about -57°C by Western test methods) but also a low flash point (a minimum of 28°C compared with 38°C for Western fuels, though the methods used give slightly different results). TS-1 (regular grade) is considered to be on a par with Western Jet A-1 and is approved by most aircraft and engine manufacturers.

2.4.2 Military Specifications for Aviation Fuels NATO and military organizations use another system of classification of jet fuels. Within the NATO Alliance fuels are standardized to achieve interoperability and interchangeability. NATO designates NATO-code numbers to jet fuels. These standardized jet fuels each have their own (military) specification. Guide specifications for these NATO standardized jet fuels are set in STANAG/AFLP 3747 [35], approved by the member nations under the Petroleum Committee of NATO.

The NATO standardized jet fuels are: • F-34: This is a military kerosene type aviation turbine fuel containing military fuel additive package: Static Dissipator Additive (SDA), Lubricity Improver Additive (LIA) (previously cited as corrosion inhibitor/lubricity improver additive) and Fuel System Icing Inhibitor (FSII)3 and may contain Antioxidant (AO) and Metal-Deactivator Additive (MDA). F-34 is used by land based military gas turbine engined ground vehicles and equipment in all NATO countries4. F-34 is also known as JP-8 or AVTUR/FSII.

3 FSII NATO Code S-1745. Additive to aviation turbine fuels as system icing inhibitor. 4 Until 1986 F-40 was used by land based gas turbine engined aircraft in all NATO countries except France and the United Kingdom which had converted to F-34 some 15 years earlier. Following a decision by NATO Defence Ministers all nations except Turkey switched from F-40 to F-34. The conversion (known as Stage 1 of the Single Fuel Concept) was completed in 1988.

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Jet A-1 or AVTUR + Additives5 = JP-8 or AVTUR/FSII. • F-35: This is a military kerosene type aviation turbine fuel equivalent to that used by most civil operators of gas turbine engine aircraft. Also known as Jet A-1 or AVTUR. • F-44: This is a military high flash point kerosene type aviation turbine fuel with FSII used by ship born military gas turbine engine aircraft in most NATO countries. Also known as JP-5 or AVCAT/FSII. • F-24: This is a military kerosene type aviation turbine fuel conforming to ASTM D1655, type Jet A, containing the following additives: treated with S-1745 FSII, S-1747 Lubricity Improver Additive (LIA) per STANAG 3390, and Static Dissipator Additive (SDA), blended into the fuel in sufficient concentration to increase the conductivity of the fuel to between 50 and 600 pS/m at ambient temperature or 29°C, whichever is lower.

The following are the corresponding military jet fuel specifications: • F-34: • Def Stan 91-87 Iss 6 (2009) [36]. • MIL-DTL-83133J (2015) [37]. • DCSEA 134/D (2015) [38]. • CGSB-3.24-2016 [39]. • TL 9130-0012 Ed. 9 (2012) [40]. • F-35: • Def Stan 91-091 Iss 9 (2016). • MIL-DTL-83133J (2015). • DCSEA 134/D (2015). • F-44: • Def Stan 91-86 Iss 6 (2009) [41]. • MIL-DTL-5624W (2016) [42]. • DCSEA 144/D (2015) [43]. • CGSB-3.24-2016. • F-24: • ASTM D1655 + the additives above.

5 The term “additives” can include FSII, LIA and SDA. Metal deactivator, MDA, and thermal stability “+100” additives may also be required, though the former is not permitted by US Navy.

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Chapter 3 − JET FUEL APPROVAL PROCESSES

3.1 OVERVIEW OF THE CIVIL FUEL APPROVAL PROCESS FOR ALTERNATIVE JET FUELS

3.1.1 Context Due to the specific terms of use in an aircraft (exposure to the cold in the tanks, need for high energy content, etc.), jet fuels must meet tight quality specifications to guarantee flight safety. These specifications are supervised by international standards (ASTM, Def Stan) and their adaptation to the alternative jet fuels has required the definition of a specific new approval process and standard.

The first approved alternative jet fuels were obtained either through the Fischer-Tropsch (FT) process or by vegetable oils and animal fats hydroprocessing. They contain paraffins (linear or isomerized alkanes). Those molecules already represent around 60% of the ones it is possible to find in a fossil jet fuel. As they are aromatic-free, these alternative fuels can only be used blended to a fossil jet fuel up to a 50% ratio. A minimum level of aromatic compounds is required to guarantee fuel compatibility with materials in the current systems.

During the approval of these fuels, resemblance as close as possible to conventional Jet A-1 was required to ensure they are “drop-in”. However, the accepted limits for the fuel properties do not always have an absolute technical justification. For example, the minimum percentage of 8% set for aromatics was chosen from the historically minimal value observed and for which no materials compatibility issues, like leakage, were known.

New processes are emerging whose neat, unblended products, though hydrocarbons within the jet fuel range and experience, have greater differences with conventional Jet A-1 or Jet A. This is particularly the case for certain fermentation processes which lead to the production of a reduced number of molecules. The substitution of fossil aromatics by synthetic aromatics is also envisaged, which could require understanding their impact on the fuel properties.

3.1.2 Terms of Use of Jet Fuels on Civil Aircraft To be used on an aircraft, the properties of a jet fuel must meet a specification that imposes limits on a number of physical and chemical characteristics. The best known of these specifications are ASTM D1655 [32] and Def Stan 91-091 [31], formerly Def Stan 91-91.

All the required properties, however, are not defined explicitly by the specification; the specification simply controls a reduced number of parameters for a product whose origin and production conditions are framed and already approved. The new approval process comprises a series of tests range from jet fuel physico-chemical properties to components or complete engine tests.

The issue of the introduction of new fuels in aviation has mainly consisted of defining the process (now codified by ASTM D4054 [44]). Its formalization was necessitated by the emergence of products whose sole origin was no longer a historic oil source, and whose characteristics were therefore likely to differ significantly from those of fossil kerosene.

Ensuring the “drop-in” character of new fuels is now regarded as a condition of their use due to operational problems and infrastructure costs involved by the introduction of an incompatible fuel. Jet A-1 or Jet A is taken

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As part of the proposed evaluation of the consequences of a change in the composition of a fuel, ASTM D4054 provides a guide to the different properties and the expected/desired jet fuel behaviour.

3.1.3 Approval of Fuel from Alternative Pathways To be eligible for use, “new” fuel must undergo a full approval process defined by the ASTM D4054 standard. The fuel is submitted to a large range of tests (physico-chemical properties, component testing, engine testing, etc.). The objective of this approach is to demonstrate the safety of use of the jet fuel. During the approval process, ASTM research reports are produced at various stage gates; these are appropriately screened and reviewed by OEMs and also the Federal Aviation Administration (FAA) as shown in Figure 3-1. At the conclusion of the study, the reports are submitted to all the ASTM members along with a new or revised annex proposed for inclusion in ASTM D7566, and a ballot takes place. In the case where it is positive, and subject to normal specification balloting processes, the fuel is added in the ASTM D7566 [45] authorized jet fuel list as a new or revised Annex. This standard was first introduced by ASTM in 2009. It defines the alternative jet fuel blending proportions; it also describes the physico-chemical property values which the neat fuel component and the blend after mixing with conventional kerosene must meet.

Figure 3-1: Pictorial Overview of the ASTM D4054 Fuel and Additive Approval Process (Source: Mark Rumizen, FAA, 2017).

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3.1.4 Description of Steps of the General Procedure for Certification of Jet Fuel The ASTM D4054 approach is divided into several stages (Figure 3-1 and Figure 3-2). These steps are progressive and eliminatory. The first step (Tier 1) corresponds to a physico-chemical analysis of the fuel as it is conventionally done, for example, in a refinery to check the fuel conforms to the ASTM D1655 and Def Stan 91-91 standards. In the event of non-compliance, the fuel is rejected. However, if the fuel is found to be in compliance, it is then possible to take the next step. This corresponds to the “Fit-for-Purpose” tests (Tier 2). It is also, at this stage, that non-standard physico-chemical characterizations are carried out. The aim is often to look at the evolution of a property as a function of the temperature, and to evaluate properties that are not checked explicitly in the ASTM D1655 and Def Stan 91-91, or other specifications. The conformity of the “new” fuel is evaluated in this step by comparison with the classic behaviour of conventional fossil kerosenes. If no significant difference has been observed, the next steps are then undertaken.

Figure 3-2: ASTM D4054 Testing Requirements [46].

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Tier 3 is characterized by tests related to the interactions between the fuel and single engine or fuel system elements (pump, injector, etc.), and Tier 4 by tests related to the fuel and complete systems (engine). Only those tests, as requested by the Original Equipment Manufacturers (OEMs) after their inspection of the earlier Tier test results, will be performed. The Tier 3 and 4 results are then compiled in a comprehensive technical document, which includes details about the new kerosene production process, and is then submitted to the review of the OEMs.

3.1.5 Current Developments on Alternative Fuels Until July 1999 and the introduction of the jet fuel produced by Sasol, the SSJF (Semi-Synthetic Jet Fuel), the only authorized source for the production of jet fuel was oil. The application by Sasol to the United Kingdom MOD Aviation Fuels Committee for approval in Def Stan 91-91 for the use of synthetic hydrocarbons, produced from coal and obtained from the Fischer-Tropsch (FT) process, marks the starting point of alternative fuels in aviation. The SSJF has been used at the Johannesburg International Airport, since the end of 1999. According to the company, its use is completely “transparent” and has no impact on air quality, security, maintenance, storage or handling.

Up to 2009, the Sasol SSJF was the only alternative fuel approved for use. In September 2009, a step towards the generalization of alternative jet fuels was taken with the generic approval of Fischer-Tropsch fuels. This was followed by the approval of hydrotreated oils in 2011.

The Fischer-Tropsch process is not new and was used to produce gasoline for aviation during World War II. It consists of “breaking” a first organic material (coal, gas or biomass) to produce syngas consisting of carbon monoxide and hydrogen gas which is then recombined to a hydrocarbon liquid (or solid) by Fischer-Tropsch synthesis (CO + H2  (CH2)n + H2O). One of the advantages of the process is to produce a fuel with constant characteristics, irrespective of the raw material used.

Fischer-Tropsch Synthetic Paraffinic Kerosene (FT-SPK) fuels are aromatic-free. This led to limit their blending rate to 50% in the conventional fuel, Jet A -1. Indeed, aromatics constitute important components for all the qualities required for jet fuel. Reducing the aromatic content brought down, among others, density, viscosity, and compressibility of the fuel. Moreover, with too low an aromatic content, it may no longer be possible to seal the fuel system, especially with nitrile seals. Different studies show that an aromatic minimum rate is required to ensure the swelling of the seals, in particular for older ones. The minimum level is now fixed at 8%; this “restriction” on aromatics is to alleviate concerns about seal swell until research determines the actual need and defines the lower limit if necessary”. [47], [48]

The second approved class of fuels, the Hydro-processed Esters and Fatty Acids Synthetic Paraffinic Kerosenes (HEFA-SPK) are produced from vegetable oils or animal fats. The fuel characteristics are very similar to those of Fischer-Tropsch fuels. This type contains mainly paraffins (linear or isomerized alkanes). This process consists of removing the oxygen molecules of a fatty acid by hydrogenolysis and hydrogenation:

Usage conditions (50% maximum blending rate) are thus identical to those of Fischer-Tropsch fuels.

As indicated previously, new processes are emerging whose products, though hydrocarbons have greater differences with Jet A-1 and Jet A. This is particularly the case for certain fermentation processes which lead to

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Synthesized Iso-Parrafins (SIP) fuel, also called farnesane, developed by Amyris/Total company, was approved in June 2014. It can be blended up to 10% in a fossil fuel. The main differentiator of this fuel, compared to FT-SPK and HEFA-SPK alternative fuels, is that farnesane consists only of branched alkanes having 15 carbon atoms. This singularity partly explains its low incorporation rates.

Synthesized Paraffinic Kerosene plus Aromatics (SPK/A) was approved in November 2015.

Alcohol To Jet Synthetic Paraffinic Kerosene (ATJ-SPK) was approved in April 2016. It is obtained from an alcohol called isobutanol that is derived from renewable feed stocks such as sugar, corn or forestry residues.

Table 3-1 presents a summary of the already approved jet fuels.

Table 3-1: Approved Jet Fuels and Their Main Characteristics.

ASTM Month Blending Ratio D7566 and Name Process Feedstock Hydrocarbons in a Fossil Fuel Annex Year (% Volume) Syngas from Gaussian June A1 FT-SPK Gasification coal, gas, distribution of 50 2009 biomass alkanes Gaussian July HEFA- Fats, oils and A2 Hydroprocessing distribution of 50 2012 SPK greases alkanes June Branched A3 SIP Fermentation Sugars 10 2014 alkanes (C15) Gasification For FT part Gaussian Nov Alkylation of non- only: Syngas A4 SPK/A distribution of 50 2015 petroleum derived from coal, hydrocarbons light aromatics gas, biomass (primarily benzene) Sugar, corn Limited number April Fermentation A5 ATJ-SPK or forest of C12 and C16 30 2016 (isobutanol) wastes. alkanes

It is noteworthy that other alternative jet fuels produced from original pathways are under consideration through the ASTM process. These include: High Freezing Point Hydroprocessed Esters and Fatty Acids (HEFA+), Alcohol to Jet Synthetic Paraffinic Kerosene (ATJ-SPK) from ethanol, Alcohol to Jet Synthetic Kerosene with Aromatics (ATJ-SKA), Kior Hydrotreated Depolymerized Cellulosic Jet (HDCJ), ARA Catalytic Hydrothermal Cellulosic Jet (CHCJ), Virent Synthetic Kerosene with Aromatics (SKA) and Virent Synthetic Kerosene (SK), and Global Bio Energy. Other candidate fuels are also about to start the approval process.

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3.2 OVERVIEW OF THE MILITARY FUEL APPROVAL PROCESS FOR ALTERNATIVE JET FUELS The US military developed a process, documented in MIL-HDBK-510A [49], to evaluate, approve, and certify fuels and fuel additives for use in military aviation-fuel using and handling equipment. This process was developed to fill a known gap in knowledge and provide a single integrated and cost effective process for clearing all military platforms instead of a system by system evaluation. Since the first version of MIL-HDBK- 510A was published on 1 October 2007, ASTM D4054-09 [50] was conceived and modified to provide a commercial version of the alternative fuel approval process.

As the scale of the fuel approval and platform certification process became apparent, rather than having two discrete processes a decision was taken to bring the commercial and military processes together, with the military process being provided alongside the commercial process (ASTM D4054) as additional guidance to support military specific requirements for certification. Whilst this alignment allows fuels to be approved for military and commercial use in parallel, this should be done with the recognition that there are some military- unique mission-driven requirements may keep the specifications from being identical in some areas. It is a requirement on the platform system’s Technical Authority to ensure sufficient consideration of the military platform performance characteristic is taken when certifying a platform to use alternative fuel.

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Chapter 4 − LINKAGES BETWEEN CIVIL AND MILITARY SPECIFICATIONS

In Chapter 2 of this report, the applicable civil and military specifications for civil and military jet fuels were summarized. There are clear linkages between most military jet fuels and civil jet fuels, as shown in Table 4-1 below.

Table 4-1: Civil and Military Jet Fuels Classifications.

Civil Jet Fuel Designation Military Jet Fuel Designation

Jet A None Jet A + Military additive package1 F-24 Jet A-1 F-35 (may contain LIA) Jet A-1+ Military additive package1 F-34/JP-8 None F-44/JP-5

4.1 REFERENCES TO SYNTHETIC COMPONENTS IN FUEL SPECIFICATIONS With respect to allowing blending synthetic components in jet fuel it is important to examine how different civil and military jet fuel specifications address the use of these synthetic components.

ASTM D7566-16b [45] is the standard specification for Aviation Turbine Fuel containing synthesized hydrocarbons. A blend manufactured and released to all the requirements of Specification D7566 meets the requirements of ASTM Specification D1655. Details on approval of synthetic fuel blends can be found in Chapter 3.

The following subsections are the references (or lack thereof) to synthetic components in various civil and military jet fuel specifications.

4.1.1 ASTM D1655-16c (2016) [34] Specification for Jet A and Jet A-1 refers to ASTM D7566 regarding the use of approved synthetic components/blends. Annex A of ASTM D1655 states: “Aviation turbine fuels with synthetic components produced in accordance with Specification D7566 meet the requirements of Specification D1655.”

1 Additive package includes FSII/SDA and LIA.

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4.1.2 MIL-DTL-83133J (2015) JP-8 (F-34) and F-35 [37] Regarding the use of synthetic components, MIL-DTL-83133J states: “All US Navy and US Air Force aircraft are certified for the use of fuel containing FT-SPK and HEFA- SPK. All tactical/combat equipment/vehicles in the US Army Ground fleet are approved to use fuel containing FT-SPK and HEFA-SPK.” “Platform certification/approval process is still on-going for US Army Aviation.” “3.1.1 Synthesized Materials. With the approval of both the procuring activity and the applicable fuel technical authorities listed below, up to a total 50 volume percent of the finished fuel may consist of Synthesized Paraffinic Kerosene (SPK) derived from a Fischer-Tropsch (FT) process meeting the requirements of Appendix A (see A.2) or SPKs derived from Hydroprocessed Esters and Fatty Acids (HEFA) meeting the requirements of Appendix B (see B.2). … Finished fuel containing FT-SPK shall conform to the properties of Table A-II in addition to those of Table I. Finished fuel containing HEFA-SPK shall conform to the properties of Table B-II in addition to those of Table I.”

Conclusion: There is no reference in MIL-DTL-83133J to the ASTM D7566, but there are annexes in the specification for two specific synthetic components: FT-SPK and HEFA.

4.1.3 MIL-DTL-5624W (2016) – JP-5 (F-44) [42] This specification states: “The fuels supplied under this specification shall be refined hydrocarbon distillate fuel oils, which contain additives. The feedstock from which the fuel is refined shall be crude oils derived from petroleum, oil sands, oil shale, synthesized hydrocarbons, or mixtures thereof.”

Regarding the use of synthetic components, the MIL-DTL-5624W states: “3.1.1 Synthesized Paraffinic Kerosenes (applies to Grade JP-5 fuel only). A maximum of 50 percent volume of the finished fuel may consist of Synthesized Paraffinic Kerosene (SPK) blend components derived from Fischer Tropsch (FT) produced SPK or Hydroprocessed Esters and Fatty Acids (HEFA). FT-SPK blend components shall conform to the requirements in ASTM D7566 Annex A1. SPK blend components derived from HEFA shall conform to requirements in ASTM D7566 Annex A2. Finished fuel shall conform to the properties listed in Tables I and III. Finished fuel shall contain additives in accordance with 3.3 through 3.3.6. 3.1.2 Synthesized Iso-Paraffins from Hydroprocessed Fermented Sugars (applies to Grade JP-5 fuel only). A maximum of 10 percent volume of the finished fuel may consist of Synthesized Iso-Paraffins (SIP) blend components derived from Hydroprocessed Fermented Sugars. SIP blend components shall conform to the requirements in ASTM D7566 Annex A3. Finished fuel shall conform to the properties listed in Tables I and III. Finished fuel shall contain additives in accordance with 3.3 through 3.3.6.”

Conclusion: MIL-DTL-5624W refers to ASTM D7566 for specifying synthetic components, but allows only three synthetic components: FT-SPK, HEFA and SIP.

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4.1.4 CGSB-3.24-2016 [39] With respect to the use of synthetic blends, CGSB-3.24-2016, which superseded CGSB-3.24-2012, states that: “4.2 Synthetic hydrocarbons shall consist predominantly of hydrocarbons derived from non-petroleum sources such as biomass, natural gas, coal, fats and oils by processes such as gasification, reforming, Fischer-Tropsch synthesis, and hydroprocessing or hydrocracking. Synthesized paraffinic kerosene (SPK) is the name given to synthetic blending components. 4.2.1 Synthetic hydrocarbons are only permitted in jet fuel in a blend with conventional hydrocarbons. The synthetic blending component shall meet the requirements of ASTM D7566 and it may be used as a blending component up to 50% by volume. Once a batch of aviation turbine fuel containing synthetic hydrocarbons is manufactured, blended and released to the specifications of CGSB‑ 3.24 then the extended requirements specified in 5.142 are no longer applicable. Any re-testing shall be done to the requirements of CGSB-3.24, excluding 5.14.”

Conclusion: There is a direct reference to ASTM D7566 without any restrictions.

4.1.5 Def Stan 91-091-Iss 9 (2016) [33] With respect to the use of synthetic components, the specification (Section 4.1.2) states that: “Fuels containing synthetic components derived from non-petroleum sources are only permitted provided that they meet the requirements of Annex D, in addition to those defined in clause 5, Quality Assurance.”

Annex D states that: “D.1.1 Previously this Standard has only permitted those fuels solely derived from petroleum sources. However, it must now be recognized that there is an emerging requirement for this Standard to encompass and control the use of fuels containing hydrocarbons synthesized from non-petroleum sources. The use of synthesized hydrocarbons represents a departure from experience and also from some of the key assumptions on which the requirements of this Standard have so far been based. As such, it had been deemed necessary to approve Jet fuels derived from alternative sources on a case by case basis dependent on the initial raw material and production process. These specific approvals are listed at D.4. Today, this principle still holds for fuels derived from alternative sources unless it is demonstrated that the alternative fuel type conforms to ASTM D7566 Annex A1, Annex A2 (see D.3), Annex A3 (see D.5) or Annex A4 (see D.3). It must be noted that synthetic fuel components must meet all the requirements of ASTM D7566 including batch testing and extended test requirements. D.1.2 Applications for the approval of synthetic fuels or for semi synthetic blends not covered by ASTM D7566 Annex A1, Annex A2, Annex A3 or Annex A4 should still be made to the Technical Authority. D.1.3 It is the Technical Authority’s intention to revise and rewrite Annex D for Issue 10. The introduction of two new approved synthetic fuel components in ASTM D7566 (Annex A3 and Annex A4) means that this Annex has become over complicated.”

Annex D.4 also defines specific manufacturer approvals for Sasol semi-synthetic jet fuel blends and Sasol fully synthetic jet fuel.

2 The extended requirements refer to Synthetic hydrocarbon content (% by volume), Aromatics (% by volume), Distillation temperature differences (°C), and Lubricity, at point of manufacture (mm).

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Conclusion: Def Stan 91-091 refers to ASTM D7566 specifying synthetic components but allows only four synthetic components: FT-SPK, HEFA, SIP and FT-SPK/A. Also, two manufacturer-specific manufacturer approvals are specified.

4.1.6 Def Stan 91-87-Iss 6 (2009) [36] With respect to the use of synthetic components, the specification states that: “Fuels containing synthetic components derived from non-petroleum sources are only permitted provided that they meet the requirements of Annexes A and C in addition to those defined in clause 5.”

Annex C states that: “As an interim solution it has been deemed necessary to approve fuels containing synthetic components on an individual basis and identify test requirements specific to synthetic blends. Applications for approval of synthetic fuels or blends should be made to the Technical Authority. … … Testing may also be required to demonstrate satisfactory operational performance. The requirement and scope of such testing will be defined by agreement with the Technical Authority in conjunction with the appropriate certifying authority, aircraft and engine manufacturers. Such testing may include but not be limited to evaluation of prototype blends to assess the impact of synthetic components on the following operational parameters”

In this edition of the Def Stan 91-87 two specific approvals are specified (based on Fischer-Tropsch process): • SASOL Semi-Synthetic Blends; and • SASOL Fully Synthetic Jet Fuel.

Conclusion: Def Stan 91-87 does not refer to ASTM D7566. Nevertheless, it specifies two manufacturer specific approvals.

4.1.7 DCSEA 134 Ed D 2015 (F-34) / DCSEA 144 Ed D 2015 (F-44) [38], [43] With respect to the use of synthetic components the specification states that: “The fuel shall be a conventional distillate fuel. However, other compositions like synthetic components such as SPK from FT or other processes need to have had a formal approval by the technical authority/airworthiness authority before its use.”

Conclusion: Reference is made to synthetic components; however, a case-by-case approval is necessary.

4.1.8 TL 9130-0012 Ed E 2012 (F-34) [40] With respect to the use of synthetic components the specification states that: “F-34 shall consist of a blend of hydrocarbons with additives.”

Conclusion: There are no references to synthetic blends or components.

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4.1.9 STANAG 3747 – Ed11 / AFLP 3747 EdB-v1 2016 [35] With respect to the use of synthetic components the specification states that: “0106 Synthetic components meeting the requirements of ASTM D7566 (Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons) are allowed by several fuel specifications such as ASTM D1655, DEF STAN 91-91, MIL-DTL-5624, and MIL-DTL-83133, which characterize aviation turbine fuels defined by this STANAG. Before any fuel containing synthetic components may be delivered to a NATO aircraft it must first be ascertained that the appropriate clearance document(s) permitting its use have been obtained. Typically, clearances would be provided by the technical authority for the fuel in concert with the Original Equipment Manufacturers (OEM), weapon system manager, airworthiness authority and/or aircraft engineering officer.”

Conclusion: There is a reference to specifications that refer to ASTM D7566. Delivering fuels with synthetic components to NATO-aircraft only allowed after platform certification.

4.2 CONCLUDING REMARKS • Some military specifications refer to ASTM D7566 when synthesized hydrocarbons are mentioned. • Some military specifications (MIL-DTL 5624W and DefStan 91-91) refer only to specific annexes of ASTM D7566. • Def Stan 91-87 only refers to two specific manufacturer approvals, both from SASOL. • The US Mil-DTL-83133J only refers to FT-SPK and HEFA-SPK as approved synthetic fuels, without any reference to ASTM D7566. • In some cases, despite referencing ASTM D7566, an approval/clearance by a military technical fuel authority and/or airworthiness authority is needed before the synthetic blend can be used (STANAG/AFLP 3747).

For quick reference, Table 4-2 and Figure 4-1 summarize the references to synthetic blends, and to ASTM D7566.

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Table 4-2: References to Synthetic Fuels and ASTM D7566 Approved Annexes in Various Fuel Specifications.

Approval by Reference Fuel Fuel Technical Reference to Synthetic Blends to ASTM Designation Authority D7566 Required? STANAG/ Yes Yes Yes AFLP 3747 (Ed B-v1 2016) TL 9130-0012 E F-34 No No Not applicable DCSEA 144/D F-44 Yes No Yes DCSEA 134/D F-34 Yes No Yes Def Stan 91-87 F-34 Yes, Sasol Semi-synthetic and No Yes Iss 6 Sasol Fully synthetic Def Stan 91-091 Jet A-1/F-35 FT-SPK, HEFA-SPK, SIP, Yes For other Iss 9 FT-SPK/A, Sasol Semi- synthetic fuels synthetic and Sasol Fully covered in synthetic ASTM D7566 CGSB-3.24-2016 F-34/F-44 Yes Yes No MIL-DTL-5624W JP-5/F-44 Only FT-SPK, HEFA-SPK, Yes No SIP MIL-DTL-83133J JP-8/F-34 Only FT-SPK, HEFA-SPK No No ASTM D1655-16c Jet A/A-1 Yes Yes No

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FT-SPK HEFA

MIL-DTL- MIL-DTL- 5624W 83133J

Sasol A1, A2, DCSEA Fully A3 134/D synthetic 144/D

Def Stan Sasol A1, A2, A1 Fully 91-091 Iss 9 A3. A4 FT-SPK synthetic Sasol Def Stan Semi- A2 A3 synthetic HEFA SIP 91-87 ASTM Sasol D7566 Semi- synthetic

A4 A5 FT-SPK/ ATJ-SPK A TL9130- CGSB-3.24- A1, A2, A3. A4, 0012 E 2016 A5 A1, A2, A3. A1, A2, A3. A4, A5 A4, A5

ASTM AFLP 3747* D1655-16c

* Technical Approval Needed

Legend

denotes standards with linkages to ASTM D7566

denotes standards without linkages to ASTa 57566

denotes synthetic components

Figure 4-1: References to Synthetic Fuels and ASTM D7566 Approved Annexes in Various Fuel Specifications.

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Chapter 5 − ADDITIONAL CONSIDERATIONS FOR MILITARY APPROVAL OF FUELS

5.1 BACKGROUND A tendency has been observed on the part of some Original Equipment Manufacturers (OEMs), particularly those not as well integrated with the ASTM process for approval of synthetic jet fuels, to seek elaborate testing of ASTM D7566-approved fuels prior to their introduction in their military platforms. This adds significant cost, time and effort for the certification of such platforms when the effort may already be redundant.

In AVT-225’s quest to gain a better understanding of this issue, in the fall of 2015, on the side-line of the IASH 2015 conference in Charleston, South Carolina, USA, a workshop was held with selected invited participants to identify if there were any additional considerations for approval of aviation jet fuels in the context of military platforms. To support the discussion, a questionnaire was also drafted and sent to experts in the OEM and defence community for their inputs beforehand. A verbatim summary of the survey questions and responses is presented in Annex C. A summary of the meeting attendees and minutes is presented in Annex D.

5.2 LACK OF CONSENSUS ON NEED FOR ADDITIONAL TESTING As evidenced from the responses to the survey in Annex C, some notable (not insignificant) differences in position regarding the need for further fuel approval tests for military platforms were found.

From the ensuing discussion, the consensus position was that once a fuel is approved in ASTM D7566, it should be acceptable for use on all platforms accepting ASTM D1655 fuel with no further issues, and that, if some OEMs had issues, these should have been raised and dealt with during the ASTM approval process.

It was mentioned that the Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA) had issued communications [51], [52], [53] that recognized fuels conforming to ASTM D7566 as being acceptable for use on platforms certificated for ASTM D1655 Jet A or Jet A-1 fuel. A Certification Memorandum issued by EASA [53] had further recommended the active participation in aviation fuel committee(s) as one of the means of having a robust system in place for following changes to fuel specifications and evaluating impacts on products. It was also mentioned that US Department of Defense (DoD) and most major OEMs are already engaged in the approval process.

It was mentioned by some national representatives that OEMs have cited equipment differences between their own platforms and those used in ASTM testing process for wanting to carry out further trials. It was agreed that in such a case, the OEM should be requested to be specific on exactly which technical parameter was missed in the ASTM testing process, and put forward a logical technical case for the required trials.

It was also mentioned that some OEMs have also cited differences in the synthetic blend fuel properties (as being outside of their limits of experience), even while staying within existing specification ranges, as further reasons for testing. It was discussed that this position was flawed as the equipment is technically certified for the full bounds of permissible limits in a fuel specification and not just a specific range within it. Moreover, there is a good probability that the equipment may already have been subject to these outside-of-experience limits during their operation in different theatres, as well as other fuels such as JP-4 and JP-5.

The question of what specific fuels are specified by the OEM on their platform and equipment user manuals arose. If D1655 is specified, then because D7566 already permits re-identification as conventional jet fuel,

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the question of further OEM approvals may not arise. The linkages between various military fuel specifications and D1655/D7566 are further explored in Chapter 4 of this report.

It was generally agreed that it was important to raise the awareness of military technical platform authorities, program management, airworthiness authorities, and OEMs to a common understanding of the alternative fuel qualification process to allay concerns, and accelerate their adoption. Consequently, it was suggested that AVT-225 consider the production of a military user’s guide as a deliverable for the group, which has led to the current document. It was agreed that the NATO Fuel and Lubricants Working Group (FLWG) body could be a host for this document.

5.3 REASONS WHY ADDITIONAL TESTING MAY / MAY NOT BE REQUIRED Table 5-1 provides an overview of the reasons/evidence that is required to support certification of air platforms to use synthetically produced aviation fuel. This non-exhaustive list provides guidance to support decisions over platform certification although each case should be considered on an individual basis; some platforms may require more evidence to support certification than others.

Table 5-1: Reasons to Support/Not Support Platform Certification with New Fuel.

Reasons/evidence to support certification of your Reasons why additional evidence may be required platform with a candidate synthetic jet fuel • ASTM D4054 process complete and fuel approved • Platform being assessed is a legacy platform that may require for use within ASTM D1655 specification (for specific testing not undertaken through the ASTM D4054 route. which the platform is already certificated for). (Refer to Fuel Research Reports for what has been implemented.) • Platform has a performance envelope similar to • Some materials are present in the platform engine and/or fuel commercial (or civil) aircraft. system that were not assessed within ASTM D4054 process. • Platform has an operability envelope similar to • Equipment characteristics of the platform were not assessed commercial (or civil) aircraft. within the ASTM D4054 fuel approval process. For e.g., it has: • Although, the ASTM D4054 process is not • Different type of combustor fuel injection system. complete, a similar specification of fuel has already • Afterburner or thrust augmentation system (Screech or been cleared through the ASTM process. combustion instabilities). • The same platform has already been cleared to use • Special fuel conditioning: e.g. “Fueldraulics”. the fuel in other NATO nations. • The platform’s performance or operability (flight) envelope extends to outside that which is normally considered within • A similar platform has already been cleared to use 1 the fuel. the ASTM D4054 process. For e.g.: • Very high altitude operation. • The platform’s engine and fuel systems are common to an already-cleared platform for the • Supersonic speeds. fuel. • High manoeuvrability. • Infrared signature. • Transient engine performance.

1 Whilst there may be distinct military platform requirements which may justify further ASTM D4054 Tier 3 or Tier 4-type testing, it is important to seek out the specific technical fuel property/characteristic of concern (as it relates to platform or equipment performance or operability) that has not been adequately already tested during the D4054 approval process, rather than just dwell in generalities. The OEM review process currently undertaken during the ASTM D4054 process is a comprehensive, lengthy and costly endeavour, and it is more likely that specific concerns have already been addressed during the Tier 1 – 4 testing.

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Chapter 6 − RECOMMENDATIONS

6.1 FOR MILITARY PLATFORM TECHNICAL AUTHORITY The AVT-225 Research Task Group has attempted to provide a simplified decision flowchart (Figure 6-1) to aid the platform’s Technical Authority (TA) in certifying a platform to use an alternative candidate synthetic jet fuel. Figure 6-1 is also reproduced as a standalone chart in Annex E. The decision flowchart’s main premise is that the final authority to clear a platform rests with the platform TA, based on his/her risk-assessment of available facts.

Platform may be certified to Fuel rejected for use START use candidate fuel with Conditionally Yes on platform. restrictions.

Identify fuel specifications Does the TA certify (ASTM, Def Stan, Mil platform for use of fuel specification, etc.) that the based on previous candidate fuel is approved results? under (if any).

Yes Identify the fuel specifications (ASTM, Def Stan, Mil Undertake test and/or risk specifications, etc.) for which management to certify platform for the platform is already use of candidate fuel certified. Collaborate with other users of similar platforms to reduce costs, as necessary.

Do the fuel specifications for which the platform is already Have these concerns Platform may be certified to certified permit use of the Yes Yes already been use candidate fuel. candidate synthetic fuel? addressed? (Refer to Table 4-2 and Figure 4-1 for guidance)

No/Not Sure

Obtain Information Do the OEMs/TAs Request reasons for Yes • Fuel Properties have concerns? specific concerns • Fuel Research Reports Yes (ASTM, etc.), if any • List of platforms certified to use fuel, if any

Obtain Additional Information

Contact Does the platform • OEMs TA/MTCH* permit use • Other TAs of the candidate fuel based • NATO Working Groups No on current information? • Subject Matter Experts (Refer to Table 5-1 • Etc. for Guidance.) * TA/MTCH refers to the platform’s Technical Authority or Military Type Certificate Holder.

Figure 6-1: Decision Chart for Military Platform Certification.

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When OEMs have to be consulted, because the platform’s fuel specifications do not already permit the candidate synthetic fuel and/or the available information on the candidate fuel (specifications, research reports, prior experience on platforms, etc.) does not provide sufficient evidence of risk mitigation for use on the platform under consideration, the onus of soliciting and assessing OEM concerns and developing mechanisms of addressing them still rests with the military platform TA.

Where extensive additional testing requirements are recommended, it is advisable for the platform TA to solicit and understand the specific technical parameters (type of material, specific differences in component/ sub-component that will change the expected performance due to a specific fuel property or characteristic, etc.) that have not already been suitably mitigated during the approval process for the fuel, for instance under the ASTM D4054 [44] process. This active involvement on the part of the platform TA is critical to ensure that redundant tests are not undertaken, that can otherwise add significantly to the costs of clearing a platform for use with a new synthetic fuel.

6.2 FOR ORIGINAL EQUIPMENT MANUFACTURER (OEM) Whether your civil or military jet fuel specification is based on Jet A or Jet A-1 type fuels, the way in which all new jet fuels made with synthetic components are introduced has moved to ASTM D7566 [45] as the starting point. The final jet fuel specifications (such as ASTM D1655 [34] or Def Stan 91-091 [33] for civil) or MIL-DTL-83133 [37] or Def Stan 91-87 [36] for JP-8/F-34 or MIL-DTL-5624 [42] or Def Stan 91-86 [41] for JP-5/F-40 are accepting these ASTM D7566 fuels with additional constraints if necessary, to match existing fuel property limits1.

Anyone involved with the use of jet fuels should therefore want to play an active role in the process that sees these new fuels approved. New candidates go through the whole ASTM D4054 process and only when the final research reports are produced can the fuels go forward to be balloted for inclusion into ASTM D7566. As a member of ASTM you can vote on whether or not to accept proposed specification changes and you can also propose any changes you think are needed to the ASTM D4054 process. Ideally, this should cover the interests not only of commercial fuel users and equipment but also those of military fuel users and equipment. Being an active member allows you more insight into the work that is done for the new fuel approvals and allows you to flag any areas where you think that not all technically valid concerns are being addressed. Do not sit back and say “but it does not work for our systems” – join and make it work first time, without the need for lengthy additional approval steps for your military platforms!

ASTM is not “just for the Americans”. For jet fuel it is ASTM International and anyone with an interest in the methods and specifications that cover turbine fuels is welcome to join. Whilst a considerable amount of activity takes place at the two main meetings per year, you can still play a role in the method and specification balloting process by emails, etc. Membership, which runs from January to December, is not very expensive ($400 for an organisation, $75 for an individual). The ASTM International Web site provides information to explain how it works, to help you decide what sort of membership is most appropriate, and to sort out what sort of document subscription service is most appropriate for you and your organisation.

For anyone wanting to get involved with new jet fuels, the following Product committees and subcommittees should be your first choice, but do not feel constrained and join others too; ASTM allows you to join many other committees:

1 For instance, DEF STAN 91-091 and the Mil specs have more severe freeze point, total acidity and cleanliness requirements than ASTM D1655.

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• Main Committee D02 Petroleum Products, Liquid Fuels, and Lubricants. • Subcommittee D02.J02 Aviation fuels. • Subcommittee D02.J02.06 Emerging Turbine Fuels.

Start the process by going to the ASTM International Website membership page: https://www.astm.org/ MEMBERSHIP/index.html.

6.3 FOR FOLLOW ON AVT RESEARCH TASK GROUPS (RTG) With the end of AVT-225’s three-year term in December 2016, a new Task Group may be required to address further challenges in the ground and naval arenas, while also addressing broader concerns in other areas such as the NATO Single Fuels Policy. The Petroleum Committee Vision on Future Fuels [54] states that in the near term: • Biodiesels blended up to 5 – 10 % v/v with conventional diesel fuel appears to be the likely way ahead for ground equipment during peacetime, but the Single Fuel Policy Capability remains paramount. Today, there are synthetic fuels, for instance Gas To Liquids (GTL) and Hydrotreated Vegetable Oil (HVO), in the market that fully comply with the current range of fuel specifications but their availability is still limited. It is, however, expected that the oil companies and new fuel producers will target synthetic diesel fuel initially as the lowest risk sector. • Drop-in replacement fuels: These fuels do not require changes to engine fuel systems or the distribution network. Efforts continue to certify and approve the use of drop-in alternative fuels through commercial processes for the Aviation. These same alternative drop-in fuels will be readily seen in marine and ground fuel specifications (e.g. MIL-DTL-16884 for F-76 [55] and EN 15940 for paraffinic diesel [56]).

Consequently, a new Exploratory Team (ET), ET-171, has been formulated to propose one or more follow-on activities in these areas. The topics to be covered by the follow-on activities can include: • Scope of synthetic fuels considered includes FT-SPK, HVO, HEFA-SPK, High Freezing Point HEFA and other emerging fuels. • Alignment of military users and requirements with civil approval processes for new fuels. • Impact of blending synthetic components on fuel specifications and properties (for instance calorific value, density, cetane number, etc.) will be considered as a priority for ground diesel (F-54) and naval diesel (F-76). However, because of the NATO Single Fuel Policy, properties of jet fuels (F-35/F-34/ F-63) as relating to compression ignition engines will also need to be considered. • Impacts of synthetic fuel blends on vehicle/equipment hardware (e.g., engine parts, fuels systems/ storage, material compatibilities) as well as on mission/operational characteristics (e.g., fuels storage and handling, maintenance, emissions, performance) will be evaluated. • Impact on operations with military-owned or controlled multi-product pipelines used by civil fuel suppliers, and knock on effects to achieve “low carbon” fuel targets.

• Impact on emissions such as CO2, NOX and particulate matter. • Investigate the effects of synthetic fuels as energy source for fuel cells and impact of properties for future application in military systems (land, see, air).

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Considering the broad scope of topics and varied group expertise required, a recommended path forward may be to have two follow-on Research Task Groups (RTGs): • Land systems-centric: Implication of Synthetic Fuels on Land Systems, as well as on the NATO Single Fuel Policy (SFP). • Naval systems-centric.

The following sub-sections provide more context.

6.3.1 Impact of Synthetic Jet Fuels on the Single Fuel Policy (SFP) and Land Systems The SFP concerns the capability of using F-35/F-34 as the battlefield fuel for ground vehicles and equipment in service with Alliance Forces and for land-based military aircraft.

It does not, however, apply to Marine Operations or high density fuels for special applications. Ideally it should be applied wherever Alliance forces are deployed, in peacekeeping roles, crisis response operations and expeditionary operations.

The SFP aims to simplify the battlefield fuel logistics for NATO forces engaged in land and air operations so that: • A single fuel, an aviation turbine kerosene fuel, is supplied for all land-based operations. • The fuel is specified, distributed and used in all NATO countries. • The fuel can be introduced, stored, transported and distributed by the NPS (NATO Pipeline System).

Since the main concern of the Aviation community is the use of “drop-in” alternative fuels, similar to F-35/F-34 and fit-for-purpose in current and legacy aircraft, there are no major changes expected in the NATO SFP. The policy will also remain extant for all existing and future land-based vehicles and equipment provided and alternative fuels’ characteristics should be closely monitored to anticipate any difficulty with ground equipment.

As stated earlier, the jet fuel specifications allow the presence of certain synthetic components. Therefore a qualification and approval process is used to evaluate candidate jet fuels and determine their acceptability for use as an aviation fuel.

In alignment with the single fuel on the battlefield policy, the use of alternative jet fuels for use as ground fuels in tactical and combat vehicles and equipment will have to be investigated.

Existing fuel specifications do not address all of the properties needed to evaluate or specify non-petroleum based fuels. Properties like the cetane number, the kinematic viscosity at 40°C and the fuel lubricity are of relevance in assessing the suitability of the fuels for ground fuels, all requirements for diesel fuels.

Properties that are important to the use of jet fuels in ground vehicles and equipment include: • Density: the density will lower with increased volume of synthetic blend, especially when paraffinic components are used. Note that density may also increase in the event of aromatic synthetic components also being blended. Some engines have fuel injection systems that are sensitive to fuel density. • Cetane number: a minimum cetane number ensures that SPK blends will have an acceptable ignition quality allowing reliable starting of compression ignition engines, especially cold engines.

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• Volatility: the key volatility requirements are in terms of limits on distillation temperatures at volume percent sample recovered. Typical petroleum jet fuel has a smooth and continuous distillation curve as a result of a full complement of hydrocarbon compounds. A severely flattened distillation curve, or one that is not smooth and continuous, would be indicative of a fuel with a significantly different chemical composition from that of petroleum jet fuel. • Kinematic viscosity @ 40°C: The F-34/F-35 has no specification requirement limiting viscosity at high temperature. On the other hand, diesel fuel specifications typically have a viscosity at high temperature requirement. For some engines it is advantageous to specify a minimum viscosity because of power loss due to injection pump and injection leakage. • Lubricity: The JP-8 specification requires that a LIA (Lubricity Improver) additive be blended. All approved LIA provide a fuel lubricity of 0.65 mm or less wear scar diameter. The diesel specifications also include a requirement for lubricity. However, the test method specified is not the same as the test method used for JP-8. The HFRR (High Frequency Reciprocating Rig) is used for diesel fuel, whereas the BOCLE test method is used for aviation fuel. The HFRR test method is not sensitive to the approved type and treat rate of lubricity improvers required for JP-8. The diesel engine OEMs will continue to warranty engines based on use of fuel meeting diesel fuel lubricity requirements (HFRR). • Bulk modulus: the bulk modulus of a fluid is a measure of its resistance to compression. It has been reported that the bulk modulus of some alternative and synthetic fuels has been lower than of petroleum- based fuels, though they fall within the range of previous experience.

6.3.2 Impact of the Use of Synthetic Fuels on the Navy Recently, synthetic fuels have entered the specifications (MIL-DTL-16884N [55], STANAG 1385 [57], etc.) for the Navy fuels.

The processes for the approvals of synthetic fuels are comparable to those used for the approval of the synthetic jet fuels. However, there is no industry (ASTM) standardized method (like ASTM D4054 for jet fuels) for approval of these synthetic Navy fuels. The approvals are achieved via US Navy’s protocols [58], which follow a similar approach to D4054 but with a focus on naval applications.

STANAG 1385 mentions regarding the use of synthetic fuels the following: “The composition shall be derived from crude oil and approved synthetic fuel derived from biomass, coal or natural gas. The approved synthetic fuels are: derived from hydro processing of animal fat, plant oil or algal oil triglycerides or from synthesis gas using FT process. Any synthetic blend components must be tested to and certified to existing national standards.”

MIL-DTL-16884N states: “The fuel shall be derived from conventional material sources, synthesized materials, or mixtures thereof. A maximum of 50 volume percent of the finished fuel may consist of Synthesized Paraffinic Diesel (SPD) blend components derived from Hydroprocessed Renewable Diesel (HRD) or FT produced SPD.”

Apart from density, properties like demulsification, cetane number (ignition quality) and lubricity, the bulk modulus, microbial growth potential (low molecular weight hydrocarbons are particularly attractive to fuel- degrading microbes) and the materials compatibility are of concern and will need to be investigated when synthetic blends are used.

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Chapter 7 − REFERENCES

[1] Wikipedia, Aviation Biofuel, Retrieved from https://en.wikipedia.org/wiki/Aviation_biofuel, Accessed on 12 February 2017.

[2] Air Transport Aviation Group, Sustainable Fuels, Retrieved from http://aviationbenefits.org/ environmental-efficiency/sustainable-fuels/, Accessed on 12 February 2017.

[3] IATA, Fact Sheet Alternative Fuels, Retrieved from https://www.iata.org/pressroom/facts_figures/ fact_sheets/Documents/fact-sheet-alternative-fuels.pdf, Accessed on 12 February 2017.

[4] Qantas Airways Limited, Creating a Sustainable Future with Aviation Biofuels, Retrieved from http://www.qantas.com/travel/airlines/sustainable-aviation-fuel/global/en, Accessed on 12 February 2017.

[5] IATA, IATA Sustainable Aviation Fuel Roadmap, 1st Edition, Retrieved from http://www.iata.org/ whatwedo/environment/Documents/safr-1-2015.pdf, Accessed on 12 February 2017.

[6] T. Radich, U.S. Energy Information Administration, The Flight Paths for Biojet Fuel, 9 October 2015, Retrieved from http://www.eia.gov/workingpapers/pdf/flightpaths_biojetffuel.pdf.

[7] Sustainable Aviation Fuel Users Group, Biofuel Use, Retrieved from: http://www.safug.org/biofuel-use/, Accessed on 12 February 2017.

[8] ASTM D7566-09, Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, ASTM International, West Conshohocken, PA, 2009, www.astm.org.

[9] R. Zennaro, Fischer-Tropsch Process Economics, in: P.M. Maitlis and A. de Klerk (editors), Greener Fischer-Tropsch Processes for Fuels and Feedstocks, Weinheim, 2013.

[10] ASTM D7566-15c, Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, ASTM International, West Conshohocken, PA, 2015, www.astm.org.

[11] A. Zschocke, Achievements and Challenges in the Use of Biofuels for Aviation, Presentation at EUBCE 2015, Vienna, 1 June 2015.

[12] ASTM D7566-14a, Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, ASTM International, West Conshohocken, PA, 2014, www.astm.org.

[13] ASTM D7566-16, Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, ASTM International, West Conshohocken, PA, 2016, www.astm.org.

[14] SkyNRG, Avinor and Air BP Make First Volumes of Sustainable Jet Fuel a Reality, Oslo Gardermoen Airport Press Release, 22 January 2016.

[15] C. Harvey, United Airlines is Flying on Biofuels. Here’s Why That’s a Really Big Deal, The Washington Post, 11 March 2016.

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[16] Neste, Revolution in Plane Sight, Retrieved from https://www.neste.com/en/revolution-plane-sight, Accessed on 12 February 2017.

[17] J. Sorena, Co-Processing of HEFA feedstocks with Petroleum Hydrocarbons for Jet Production, Presentation at CRC meeting, 6 May 2015.

[18] ICAO Working Paper A39-WP/56, Sustainable Alternative Fuels for Aviation, 2016.

[19] National Science and Technology Council, Federal Alternative Jet Fuels Research and Development Strategy, Washington, D.C., June 2016, Retrieved from https://www.whitehouse.gov/sites/default/files/ federal_alternative_jet_fuels_research_and_development_strategy.pdf.

[20] ICAO Working Paper A39-WP/212, The Need for Policy Guidance for the Promotion of Sustainable Alternative Fuels for Aviation, 2016.

[21] ICAO resolution A39-3: Consolidated statement of continuing ICAO policies and practices related to environmental protection – Global Market-based Measure (MBM) scheme, 2016.

[22] B. Miller, Converting MSW Into Low-Cost, Renewable Jet Fuel, IATA Alternative Fuel Symposium, Cancún, Mexico, 5 November 2015.

[23] S. Csonka (Executive Director, CAAFI), from: Presentation Given During Informal Discussion with Canadian Government Stakeholders, 8 March 2017.

[24] A. Zschocke, S. Scheuermann and J. Ortner, High Biofuel Blends in Aviation (HBBA) ENER/C2/ 2012/420-1 Final Report, Retrieved from http://www.hbba.eu/, Accessed on 12 February 2017.

[25] J. Pechstein and A. Zschocke, Blending of Synthetic Kerosene and Conventional Kerosene, in: M. Kaltschmitt and U. Neuling (editors), Biokerosene: Status and Prospects, 2018.

[26] ASTM D1655-15d, Standard Specification for Aviation Turbine Fuels, ASTM International, West Conshohocken, PA, 2015, www.astm.org.

[27] Defense Logistics Agency, Petroleum Quality Information System 2013 Annual Report.

[28] Energy Institute and Coordinating Research Council, The quality of aviation fuel available in the United Kingdom - Annual surveys 2009 to 2013, CRC project no. AV-18-14, October 2015.

[29] M. Rumizen, Aviation Biofuel Standards and Airworthiness Approval (draft), 2015.

[30] Chevron, Aviation Fuels Technical Review, 2007.

[31] DEFSTAN 91-091, Turbine Fuel, Aviation Kerosine Type, Jet A-1, NATO Code: F-35, JSD: AVTUR, (Latest version, Revision I9, published 3 October 2016).

[32] ASTM D1655, Standard Specification for Aviation Turbine Fuels, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States (Latest version, 18a, published in 2018).

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[33] DEFSTAN 91-091/9:2016, Turbine Fuel, Aviation Kerosine Type, Jet A-1, NATO Code: F-35, JSD: AVTUR.

[34] ASTM D1655-16c, Standard Specification for Aviation Turbine Fuels, ASTM International, West Conshohocken, PA, 2016, www.astm.org.

[35] STANAG 3747 Ed. 11 (2016), Guide Specifications (Minimum Quality Standards) for Aviation Turbine Fuels (F-24, F-27, F-34, F-35, F-37, F-40 and F-44).

[36] DEFSTAN 91-87/6:2009, Turbine Fuel, Aviation Kerosine Type, Containing Fuel System Icing Inhibitor, NATO Code: F-34, JSD: AVTUR/FSII.

[37] MIL-DTL-83133J, Turbine Fuel, Aviation, Kerosene Type, JP-8 (NATO F-34), NATO F-35, and JP-8+100 (NATO F-37), 2015

[38] DCSEA 134/D, Carburéactuer pour turbomachines d’Aviation avec antiglace, 19 May 2015.

[39] CGSB-3.24-2016, Aviation turbine fuel (Military grades F-34, F-37 and F-44).

[40] TL 9130-0012 Ed. 9 (2012), Aviation turbine fuel; NATO Code: F-34; Bundeswehr Code: Fy0015.

[41] DEFSTAN 91-86/6:2009, Turbine Fuel, Aviation Kerosine Type: High Flash Type, Containing Fuel System Icing Inhibitor, NATO Code: F-44, JSD: AVCAT/FSII.

[42] MIL-DTL-5624W, Turbine Fuel, Aviation, Grades JP-4 and JP-5, 2016.

[43] DCSEA 144/D, Carburéactuer, type haut point d’Éclair, avec antiglace, 21 October 2015.

[44] ASTM D4054-16, Standard Practice for Qualification and Approval of New Aviation Turbine Fuels and Fuel Additives, ASTM International, West Conshohocken, PA, 2016, www.astm.org.

[45] ASTM D7566-16b, Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, ASTM International, West Conshohocken, PA, 2016, www.astm.org.

[46] M. Rumizen et al., ASTM D4054 Users’ Guide, A Publication of the Commercial Aviation Alternative Fuels Initiative (CAAFI) Certification-Qualification Team, 2014.

[47] C.A. Moses, Development of the Protocol for Acceptance of Synthetic Fuels under Commercial Specification, CRC Contract No. AV-2-04, 2008.

[48] C.A. Moses, Comparative Evaluation of Semi-Synthetic Jet Fuels, CRC Project n°AV-2-04a, 2008.

[49] MIL-HDBK-510A, Department of Defense Handbook: Aerospace Fuels Certification, 2014.

[50] ASTM D4054-09, Standard Practice for Qualification and Approval of New Aviation Turbine Fuels and Fuel Additives, ASTM International, West Conshohocken, PA, 2009, www.astm.org.

[51] FAA Special Airworthiness Information Bulletin, NE-11-56R2, Engine Fuel and Control - Semi-Synthetic Jet Fuel, May 19, 2016.

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[52] FAA Advisory Circular, 20-24D, Approval of Propulsion Fuels, Additives, and Lubricating Oils, June 30, 2014.

[53] EASA Certification Memorandum, Fuel Specifications, CM No.: EASA CM – PIFS – 009 Issue: 01, Issue Date: 28 February 2013.

[54] NATO Petroleum Committee, Petroleum Committee Vision on Future Fuels, AC/112(NFLWG)(EAPC) D(2014)0001 (Reproduced in Annex E).

[55] MIL-DTL-16884, Detail Specification: Fuel, Naval Distillate (Latest version, Revision N, published 2014).

[56] EN 15940, Automotive fuels – Paraffinic diesel fuel from synthesis or hydrotreatment – Requirements and test methods, 2016.

[57] STANAG 1385, Guide Specification (Minimum quality standards) for Naval Distillate Fuels (F-75 and F-76) (Latest version published 30 April 2014)

[58] SWP44FL-005, Standard Work Package, Naval fuels & Lubricants CFT Shipboard Qualification Protocol for Alternative Fuel / Fuel Sources, 16 February 2011.

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Annex A − LIST OF MILITARY OWNED OR CONTROLLED MPPL

The NATO Pipeline System consists of the following nine separate military pipeline and storage systems: • The Norwegian Pipeline System (NOPS) is not fully integrated but consists of distribution systems, storage facilities and sea terminals which are connected by short pipelines and supplied by coastal tankers. • The North European Pipeline System (NEPS) is located in Denmark and Germany. • The Central Europe Pipeline System (CEPS) located in Belgium, France, Germany, Luxembourg and the Netherlands. • The Northern Italy Pipeline System (NIPS). • The Greek Pipeline System (GRPS). • The Turkish Pipeline System (TUPS) comprises two separate pipeline systems known as the Western Turkey Pipeline and the Eastern Turkey Pipeline. • The Portuguese Pipeline System (POPS). • The Icelandic Pipeline System (ICPS).

Figure A-1: Coverage of the NATO Pipeline Systems.

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Annex B − MAKING CONVENTIONAL JET FUEL

Jet fuel quality begins at the refinery, and can only be maintained by all the fuel handling and filtration expertise that follows en route to the aircraft tanks. Shared industry jet quality procedures concentrate on post refinery practices and avoidance of contamination, but relatively little is in the common domain about how to make a good fuel in the first place. Some international oil companies have published aviation fuel handbooks, but none these, nor a handful of reference books, provide an exhaustive or up-to-date picture of the ways in which jet fuel is made. Most of the expertise lies with individuals in the refinery or with process providers.

Specifications set out “Table 2-1” criteria that should be met and also a series of written requirements (e.g., management of change, permitted materials, quality assurance, testing, documentation and traceability, cleanliness requirements) but they do not provide any guidance on how to make the fuel. A recent joint EI/JIG publication, EI/JIG Standard 15301, is starting to address the challenge of what is means to “meet specifications” and Section 6 of this deals particularly with the manufacture of jet fuel.

Almost all jet fuel derives from conventional feedstocks listed in the main specifications (such as crude oil, natural gas liquid condensates, heavy oil, shale oil and oil sands). These feedstocks are upgraded to make a whole range of products, from gases and transportation fuels to heavy fuel oils and lubricants, with the economics of the local and export markets determining the “product slate” at any point. Refineries can be simple or very complex, depending on the crudes they were designed to handle and the upgrades they have had. No two are the same and therefore the actual composition of the jet fuel made by a given refinery will be unique to that location. Even at a given refinery the jet fuel composition can vary; jet fuel is not a bulk chemical but a product that meets the minimum criteria (compositional, physical, performance and traceability/paperwork) set out in the specification(s) to which it is sold.

The first stage in the refinery process is distillation, which takes place in Crude Distillation Units (CDUs), sometimes known as Atmospheric Distillation Units (ADUs) or pots, which allow the main fractions of interest to be separated out as shown in Figure B-1. Distillation, which separates out various cuts based on boiling point ranges, sets the basic properties and yields of the cuts. Most refineries are optimised to maximise their production of gasoline or of gasoil (diesel) products, which are lighter and heavier, respectively, than kerosene and account for well over 50% of the barrel. However, distillation alone does not produce enough of these desired products required. To increase the yield, the less attractive heavier distillation products will be sent to upgrading units. For instance, the heaviest components will go to vacuum distillation units, followed by catalytic cracking or coker units to produce lighter products that are acceptable fuel components as is or with hydrotreatment. Heavier gas oils and vacuum gas oils from the vacuum distillation units can be upgraded in hydrocracking units. This leads to overall refinery production profiles as indicated in Figure B-2, based on data from the US Energy Administration Agency, EIA.

1 EI/JIG Standard 1530, First Edition, October 2013, “Quality assurance requirements for the manufacture, storage and distribution of aviation fuels to airports”, published by Energy Institute, London and the Joint Inspection Group.

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Figure B-1: Stage 1 Processing – Distillation, Which Sets Basic Properties and Yield.

Figure B-2: Regional Differences in 2013 Refinery Production. (Source of data: US Energy Administration, EIA, August 2015).

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Kerosene, most of which is used for jet production, is the fuel “in the middle” in the distillation. In the USA, the demand is for gasoline, so the jet tends to have a slightly higher initial and final boiling point than in most of the rest of the world, where diesel is the preferred fuel. This is why Jet A (the main Jet in USA) has a higher maximum freeze point than Jet A-1 (the main Jet outside USA).

The “straight run” kerosene cut from primary distillation is, typically, 8 – 10 % by volume of the crude barrel at this point. In a very few cases the straight run kerosene cut is acceptable as jet fuel with little or no further treatment. If the SR kero is the only kerosene stream available the most common treatments are: • Caustic treating, to reduce acidity. • Sweetening, to remove mercaptans and reduce acidity. Merox and Merichem are among the more common examples of this but there are still some Bender units. • Hydroprocessing, to remove sulphur and reduce acidity.

However, there are multiple outlets for the kerosene streams at a refinery: jet, domestic kerosene (used for cooking, heating and lighting), ultralow sulphur diesel blending and industrial fuel oil blending. Jet requirements usually set the quality standards, allowing the kerosene to simultaneously meet all the other, usually less stringent, requirements of the other usages. To produce enough kerosene of suitable quality for the jet market and the other outlets the refinery may need to add in more kerosene production streams, mainly through upgrading. This can provide additional hydroprocessed streams, such as mildly hydrotreated (or hydrofined) components or hydrocracked components. There are also starting to be refineries including streams derived from catalytic cracker units, with additional hydroprocessing steps to remove less stable components. So while many jet fuels are made from a single refinery stream, more complex refineries can have up to 4 or 5 kerosene streams available to make their jet, with the actual number used depending on gasoil blending demands (which can be greater in winter months) and, increasingly, the sulphur contents of the streams.

Figure B-3: Examples of Refinery Streams Blended to Make Jet Fuel.

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A very complex refinery might have some or all of the streams in Figure B-4 in its jet product, if the coker or cat cracked product were to be further treated in a hydroprocessing unit. The various streams have their plus and minus points, as summarised below in Table B-1, but eventually it is up to the given refinery to establish what works for their units, crudes and markets. The final blend or blends may vary depending on the crudes and the time of year but the jet fuel must meet the so-called “Table 2-1” criteria in the relevant specification and also have the necessary management of change processes supporting its production.

Figure B-4: Jet Fuel Blending Options at a Complex Refinery.

Table B-1: Typical Considerations for Typical Jet Processing Routes.

Wet Treatment Hydroprocessing Straight Run Caustic Sweetening Hydro Hydro (SR) Wash Treating Cracking Cost Very low Very low Relatively Expensive Most cheap expensive Suitable crudes Low S, low TAN High TAN, low S Low S crudes Many Very flexible Kero Yield Set by cut Set by cut Set by cut Set by cut Increases Thermal stability – – – + ++

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Wet Treatment Hydroprocessing Straight Run Caustic Sweetening Hydro Hydro (SR) Wash Treating Cracking Water shedding – – – + ++ Lubricity + + + – – Additive response OK OK OK Good Good

Chapter 6 of EI/JIG 1530 (see more below) discusses the suitability of various streams for jet fuel production. These are summarised in Table B-2.

Table B-2: Kerosene Streams that are Suitable for Jet Fuel Production.

OK to Use Use with Care May be Problematic Straight Run (SR) Kerosene Hydrotreated catalytically Streams containing olefins or cracked components: diolefins: • Heavy Catalytically Cracked • Chemical streams Naphtha / Gasoline (HCCN/ • Catalytically cracked HCCG) streams (neat) • Light Catalytically Cracked Cycle Oil (LCCCO) Wet treated kerosene: Kerosenes after n- or i-paraffin Chemical or refinery slops • Caustic treated removal (Section 6.5 in EI/JIG 1530) • Sweetened (Mercaptan oxidation), e.g. Merox, Mercaptan, and Bender processes Hydroprocessed kerosenes: (Treated) Coker kerosenes • Hydrotreated SR or thermally cracked • Severely hydrotreated or hydrocracked Approved synthetics

For the new synthetic components entering the jet fuel market, the controls are stricter and the individual components must meet certain criteria, not just the final jet fuel. Many of these new components derive from processes that make a broad range distillate product, with the jet stream being distilled off this total liquid product and being subjected to hydroprocessing steps similar to those used for conventional jet fuel production. There are also companies intending to co-process biocrudes with conventional crudes, mainly with a view to making more sustainable diesel fuels, and this will lead to very small amounts of bioderived component ending up in the jet streams; up to 5% volume biocontent may end up in the kerosene streams from such production units. Once again, jet is the fuel in the middle and at least for the short to medium term, if the gasoline or diesel cuts are more economically attractive they could impact on the yield and properties of the jet component that becomes available.

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B.1 OVERVIEW OF EI/JIG STANDARD 1530 This standard has been written to replace and expand on the scope of some existing industry documents, to cover aviation fuel quality concerns from the point of manufacture to the airfield perimeter. Its scope is shown schematically in Figure B-5. It was first published in October 2013 and will be updated periodically, to reflect feedback from industry sectors intending to implement it and who have views on how conformance can be achieved; it is a living document but one that is likely to become increasingly important, particularly outside the USA. Rest of World (RoW) will use it instead of the JIG 3 documentation that has been used to provide quality assurance downstream of manufacture. In particular EI/JIG 1530 may include more about additional manufacturing processes that are being used. There will be more “maybe” refinery options to consider, plus additional synthetic components that may be approved.

Figure B-5: International Jet Fuel Quality Assurance Standards from Production to Airport.

Sections in the document that are most relevant for manufacture and release of jet fuel are: • Aviation fuel QA and traceability; • Management of change/new processes; • Sampling and testing of aviation fuel; • Laboratories; • Refineries: manufacture; • Additives used in aviation fuels; • Receipts, batching, etc.; and • Synthetic fuels.

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The most relevant annexes are: • Salt dryers; • Clay treaters; and • How to claim conformance!

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Annex C – SUMMARY OF PRE-WORKSHOP SURVEY AND RESPONSES

The following are the written responses to a pre-workshop questionnaire that was sent out prior to the 4 October 2015 workshop that was held on the side-line of the IASH 2015 event in Charleston, South Carolina. 1) Has your organization been involved in the approval of synthetic jet fuels (D7566) in military platforms? If yes, according to which approval protocol?

GE Aviation GE Aviation has been actively involved in the evaluation and approval of jet fuels containing synthesized hydrocarbons. The protocols adhered to are the ASTM D4054 “Qualification and Approval of New Aviation Turbine Fuels and Fuel Additives,” and the USAF MIL-HDBK-510-1 “Department of Defense Handbook – Aerospace Fuels Certification.” GE Aviation also developed a protocol to approve fuels for the US NAVY GE engine fleet, R2010AE281 “Protocol for Certification of Alternate Fuels.” GE Aviation / Belcan GE Aviation has been involved with the approval of synthetic jet fuels Engineering Group (D7566) and for military platforms. It should be noted that many ASTM Aviation specifications (D1655, D6615 and D7566) are reviewed by a US Government Agency and approved for use “by agencies of the U.S. Department of Defense.” The approval protocols used are ASTM D4054, USAF MIL-HDBK-510-1 and for the US Navy a GE generated document, R2010AE281, Protocol for Qualification of Alternative Fuels. Rolls-Royce Yes. Rolls-Royce has been a partner with the US DOD for a number of years, supporting various alternative fuel initiatives through evaluation, testing and approval of alternative aviation fuels (ASTM D7566). The Rolls-Royce method of evaluating new fuels and additives is based on a methodology that is closely aligned with ASTM D4054 protocol. ASTM D4054 lists the associated testing required to evaluate new fuels and additives’ suitability for civil aircraft. We consider each new fuel on a case by case basis, using the rational risk and mitigation process. Based on fuel data from laboratory, fit for purpose and other test results, further evaluation plans are developed. When we conduct tests, we use rigs/engines that allow read across to other product lines, test once and use many. In addition, we cooperate with other OEMs by supporting the ASTM process where we usually only test once a particular risk. Pratt and Whitney Yes. ASTM D4054. RUAG RUAG Aerospace Services GmbH has not yet been involved in the approval of synthetic jet fuels (D7566).

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Southwest Research Yes. Institute (SwRI) / The US Army TARDEC Fuels and Lubricants Research Facility at SwRI ASTM International (TFLRF) has done the majority of the D4054 Tier 1 and 2 testing conducted in association with US Air Force Aviation Fuel Research Laboratory’s (AFRL) efforts to evaluate alternative fuel sources. We have also done the majority of the US Army TARDEC’s work in studying the effects of these fuels in diesel engines. SEA French MoD- No. POL service Department of In early days of FT approval, US MIL-STD-510 was used as a formal process National Defence but taken over by event by ASTM D4054 when USAF AFCO (Alternate Fuel (Canada) Certification Office) ceased to exist. What is in place currently is the circulation of ASTM D4054 OEM report for gap analysis to all aircraft platform engineers and airworthiness authority.

2) Is the addition of a particular synthetic fuel to the D7566 specification as an annex, in and by itself, a fully sufficient criterion for you to accept the use of these fuels on your military platforms without further testing, as it is (or should be) for your civil platforms? (Please expand on your answer, as required.)

GE Aviation Currently, the fuels that are pursued are the so-called drop-in fuels which are within the range of typical jet fuel experience. If a candidate fuel is as such, GE Aviation would consider the fuel to be fit-for-purpose after successful evaluation with the main engine and the APU. However, if GE Aviation’s review of the candidate fuel properties reveals them to be outside of experience, or even within experience but marginally, the augmenter light-off, auto-ignition, rumble, screech, and hardware evaluations might be required. GE Aviation / Belcan Yes, it is sufficient criterion. The military always comments to the use of Engineering Group augmentation as being needed to be tested. If a particular branch of the service wishes to have that demonstrated, that work would be fully supported by GE Aviation. In the acceptance of a new synthetic fuel, much research is done to assure that the new molecules lie within the normal range of Jet fuel hydrocarbons and that the blend ratios permitted keep the blended fuel performance within current jet fuel specifications, both Civil and Military. If the blended fuel meets all the starting requirements of the main engine and APU, augmenter operation is a given. Rolls-Royce No. In general, acceptance of a new synthetic fuel into ASTM D7566 permits read across from civil engine applications to military platforms. But this is not always the situation. Certain unique military applications require additional evaluations. Specific military applications can be either more challenging and/or unique (i.e. high altitude), and as such testing under these conditions may be required.

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Rolls-Royce (cont’d) Specific military testing is always considered during the Rolls-Royce risk review and mitigation process. These unique conditions are considered during the development of the whole fuel approval package. Pratt and Whitney To date, any concerns unique to military application, e.g. screech, have been addressed and resolved prior to ballot and before the synthetic fuel is included in a D7566 annex. This approach will continue. RUAG Besides the approval of synthetic fuel to be used on engines (Approval by the engine OEM), the full supply chain needs to be involved and agree to fulfil the spec. If this can be granted, we as an aircraft OEM could imagine an acceptance without further testing. Nevertheless the military certification authority is very sceptic on this topic and could ask for further testing. Southwest Research It should be. Military use of turbine fuel is minor part of the business. With Institute (SwRI) / commercial engines expecting a minimum of 20 K hours on the wing (and ASTM International many exceed 30 K and new engines have recently been introduced promising 40 K HOTW) the commercial need for quality fuel easily outweighs military interests. SEA French MoD – No, our military aviation technical authority (Direction Générale de POL service l’Armement or DGA) has to decide whether the use of it shall be allowed or not. Department of As stated previously, What is in place currently is the circulation of ASTM National Defence D4054 OEM report for gap analysis to all aircraft platform engineers and (Canada) airworthiness authority. If additional testing is required, we seek assistance of organization like the National Research Council Gas Turbine Lab. Our preference though is that commercial OEM approval within the ASTM process would be a read-across for military design/performance.

If the answer to the previous question is “No”: 3) What additional testing criteria (at a minimum) have to be fulfilled prior to their acceptable use in your military platforms, compared with ASTM D4054? In other words, what are the additional requirements that will have to be proved for military-specific applications?

GE Aviation See the response to previous questionnaire question. GE Aviation / Belcan – Engineering Group Rolls-Royce Some Rolls-Royce engines operate in unique flight envelopes, including high altitude and at cruise conditions for long cycles. These unique engine combustor conditions, materials and systems may require additional evaluation. The results from these additional tests provides additional insight into understanding the technical feasibility of using alternative fuel blends in military applications, and to estimate the impact on engine performance, safety and reliability.

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Pratt and Whitney None. Since there is no JP-8, not approving a fuel that has been included in D7566 and recertified as D1655 leaves a plane with nothing to fly on. Further, there is no way of knowing if the Jet A you are flying on contains SPK. RUAG Needs to be discussed with the authority. Southwest Research Basically, the TFLRF effort is to understand the potential issues involved in Institute (SwRI) / using semi-synthetic jet fuel in CI engines. So far, as long as the fuel is ASTM International blended with refined fuel, there are no new issues. The neat materials can be a problem. SEA French MoD – Tests shall be conducted by the DGA until 2020. POL service Department of Typically, afterburner performance and high altitude re-lights. National Defence (Canada)

4) Is engine flight-testing under operational conditions a necessary pre-requisite for military platforms?

GE Aviation If the simulated test results (e.g., from altitude engine tests) and/or fuel similarity to previously approved fuels indicate no concern, flight-testing would not be a requirement, but could be suggested. GE Aviation / Belcan It should not be. Management chains, being what they are, flight test under Engineering Group operational conditions fulfils an upper management emotional need and a lower echelon psychological need. Rolls-Royce Historically flight testing of an alternative fuel is not necessary from the Rolls-Royce “engine” centric view. A large amount of the evidence for engine approval can be obtained through the ASTM D4054 process and rig/engine testing. With that said, past flight test data has also been valuable in accessing the fuels expected performance. Flight testing permits further evaluation of the fuel and its’ effects on the multiple systems (fuel system, airframe, etc.) on military platforms. Pratt and Whitney No. RUAG For us it is not necessary, because there is no difference between civil and operational conditions. Southwest Research It is unlikely the aviation community would accept a restriction on an Institute (SwRI) / alternative fuel blend based on military performance and operational ASTM International conditions. Since the formulation effort is based on keeping fuels within the existing chemistry and performance box, a flight testing issue would just as likely mean that the engine/airframe is not compatible with the existing range of potential fuels. It is known there are engines that are not compatible with all jet fuel. The US Army has had problems with engines that are not compatible with a steady diet of Merox treated fuel.

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SEA French MoD- Unknown at the moment. POL service Department of Not really unless a specific aspect of flight performance is required. National Defence Typically, flight test has been performed so far to prove the no (Canada) harm/difference performance of semi-synthetic fuels.

5) Is there a requirement in your view to have a common Industry-perspective on determining the additional qualification and approval requirements for qualifying military platforms?

GE Aviation The industry does have a common perspective at higher level: determine between the customer and the OEM, the military specific concerns per review of fuel properties (e.g., augmenter performance), and evaluate for possible fuel impact. However, at a finer level, a procedure could be (not must be) developed to streamline evaluation and approval of fuels that are similar to previously approved fuels, and with representative engines only. This could prevent, or at least restrain, the possible tendency of any OEM or military office to test any and every engine product. GE Aviation / Belcan It would be nice to have a document agreed to by all the services and using- Engineering Group country military that outlines any additional test work thought to be needed to qualify all military platforms. Given the cultural differences among NATO Allies, this would not be the simple document it should be. Rolls-Royce I would consider this a topic for consideration and would encourage discussion within the NATO STO and AVT working groups. While there is merit to considering this common approach, I expect this to be a difficult task considering the uniqueness and sensitivity of the military platforms. Pratt and Whitney The international fuel community has already determined that ASTM D1655 civil specification will not be modified to include additional qualification or requirements to accommodate military platforms. RUAG Not that I’m aware of. Southwest Research The proper way for the military to lever the commercial fuel business is just Institute (SwRI) / what the US DOD has done through AFRL and NAWC, provide substantial ASTM International research into fuel quality. By defining the terms of expectation, these organizations have set the course for future fuels. With the formation of the mega airlines, the US DOD is no longer among the first tier of airlines as a fuel customer. Other militaries are not even on the chart. Tails do not wag dogs. SEA French MoD – This belongs to DGA. POL service Department of Typically, afterburner performance and high altitude re-lights. National Defence (Canada)

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6) If the answer to the question above is “Yes”, what are your recommendations for facilitating the establishment of this “guide” for documenting common, minimum additional testing requirements for military platforms?

GE Aviation An approach could be to: • Develop a skeletal guideline that outlines what such a document might look like. Include thoughts around fuel and engine similarity arguments towards a simplified approval. • Meet via telecom with OEMs. Keep size to a very small group – OEMs as well as key AVT-WG members (e.g., USAF and USNAVY only). Send out the document to OEMs prior to the meeting. • Share the vision, solicit feedback about how to best mature the guide. • Advance the document to 1st draft per feedback. All or a sub-set of OEMs might contribute to drafting. • Meet in-person with OEMs, preferably during a common industry meeting where key focals are present, review towards consensus, iterate as needed.

GE Aviation / Belcan Accept that the basic bended fuel (i.e. no additive packages) is designed to Engineering Group perform just like any fully derived petroleum fuel, uplifted anywhere in the world. Only require the testing of military engines which have historically recorded operational problems that have to do with basic combustion (unrecoverable stagnation stall due to inlet unstart would not be in this category, for example). Rolls-Royce I would consider this a topic for consideration and discussion within the NATO STO and AVT working groups and prefer not to comment at this time. Pratt and Whitney It would be pointless because there is no recourse other than bringing back JP-8. RUAG – Southwest Research If you do this and you find an issue that is not in line with commercial Institute (SwRI) / interests you will have two choices: ASTM International A) Develop a specialty fuel (JP-5, JP-7) to satisfy that platform. B) Put that hardware on the shelf. Remember that commercial interests primarily revolve around cost. Cost comes in two forms: Direct cost of the fuel (front end) and Maintenance Costs (back end). SEA French MoD – – POL service

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Department of Either it is embedded in the ASTM D4054 protocol or we institute a ASTM National Defence D4054 plus (+) protocol to cover military requirements. (Canada)

7) What do you feel is the best way to integrate your organization into the activities of AVT-225?

GE Aviation It might be hard for the OEMs to directly participate in the Working Group (WG) activities on an on-going basis due to resources available or lack thereof. Therefore, it might be more feasible for the WG chairs to discern the need for OEM involvement on case-by-case basis, and request participation and contribution, accordingly. Current questionnaire and the associated invitation are a good example. GE Aviation / Belcan Provide any information which better educates the task force members to the Engineering Group commonality of these new synthetic fuels with existing petroleum fuel. One facet of the research done before approval is given, or which tend to limit the quantity-use of these new blend materials, is that the goal is always to present a “drop-in” fuel, both for the purposes of re-certification to the US Civil fuel specifications and to insure transparent operation and performance of the new fuel relative to current fully petroleum fuels. There’s no mysticism Here. It is all Jet fuel. Rolls-Royce – Pratt and Whitney AVT-225 would gain significantly by participating in ASTM, CRC, and IASH and integrating that experience, knowledge, and rapport into their activities. Specific, dedicated annual meetings with the engine/airplane OEM team would probably also be productive. RUAG The benefit would be to support the AVT-225 to “convince and educate” the German military aviation authority with regard to synthetic fuel. For this RUAG Services AG would like to get a closer look “behind the scene”, information and an exchange with others AVT-225 members. Southwest Research We (TFLRF) would normally work with NATO through TARDEC in Warren. Institute (SwRI) / ASTM International SEA French MoD – As the service in charge of the French air force fuel supply, our objective is POL service just to follow the evolutions of this issue. Department of Having a complementary certification program recognized by military OEMs National Defence (engine/airframe) to complement ASTM D4054. (Canada)

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Annex D − SUMMARY OF AVT-225 MEETING AT IASH 2015

Date and Time: 13:00 – 16:30, 4 October 2015.

Location: Palmetto Hall, Wild Dunes Resort, Charleston, SC, USA.

Participants: AVT-225 Members: Shaji MANIPURATH, National Research Council (Chair) Pascale DEMOMENT, Total Robert ALLEN, Air Force Research Laboratory Joanna BAULDREAY, Shell Mickael SICARD, ONERA France Patrick BOSMANS, NATO Support and Procurement Agency, Central Europe Pipeline System Wim ZIJDERVELD, MoD, Netherlands Fabrice GUIDOTTI, MoD Belgium Toni KANAKIS, NLR, Netherlands

Invited Guests: Florian TOMAT, Centre d’expertise pétrolière interarmées Stan SETO, GE Aviation (Belcan Engineering Group) George WILSON III, Southwest Research Institute Katie FOSTER, MoD, United Kingdom Mark RUMIZEN, Federal Aviation Administration Pam SERINO, Defense Logistics Agency Tedd BIDDLE, Pratt & Whitney Jean-Pierre BELIERES, Boeing Dan BANISZEWSKI, Defense Logistics Agency Rachel FRICKER, UK Naval Air Squadron

Minutes: 1) A short introductory presentation of the AVT-225 Group was given by the Chair. 2) The main objective of the meeting was to address the question of whether further testing is required before an approved D7566 fuel can be used on a military platform. 3) Results of the pre-meeting survey were presented. 4) Some notable (not insignificant) differences in position regarding the need for further testing required for military platforms were found. This was perhaps due to the way the survey questions were posed, and an action was undertaken to clarify the positions with those not present. 5) From the ensuing discussion, the consensus position was that once a fuel is approved in D7566, it should be acceptable for use on all platforms accepting D1655 fuel with no further issues, and that, if some OEMs had issues, these should have been raised and dealt with during the ASTM approval process.

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6) It was mentioned that the Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA) had issued communications that recognized fuels conforming to ASTM D7566 as being acceptable for use on platforms certificated for ASTM D1655. It was also mentioned that US Department of Defense (DoD) and most major OEMs are already engaged in the approval process. 7) It was mentioned by some national representatives that OEMs have cited equipment differences between their own platforms and those used in ASTM testing process for wanting to carry out further trials. It was agreed that in such an event, the OEM should be requested to be specific on exactly which technical parameter was missed in the ASTM testing process, and put forward a logical technical case for the required trials. 8) It was also mentioned that some OEMs have also cited differences in the synthetic blend fuel properties (as being outside of their limits of experience), even while staying within existing specification ranges, as further reasons for testing. It was discussed that this position was flawed in that the equipment may already have been subject to these outside-of-experience limits during their operation in different theatres, as well as other fuels such as JP-4 and JP-5. 9) The question of what specific fuels are specified by the OEM on their platform and equipment user manuals arose. If D1655 is specified, then because D7566 already permits re-identification as conventional jet fuel, the question of further OEM approvals may not arise. An action to seek this information from the NATO FLWG was taken. 10) It was agreed that it was important to raise the awareness of military technical platform authorities, program management, airworthiness authorities, and OEMs to a common understanding of the alternative fuel qualification process to allay concerns, and accelerate their adoption. 11) The AVT-225 agreed to consider the production of a “military user guide” as a deliverable for the group. It was agreed that the NATO FLWG body could be a host for this document. 12) OEM reps and other invited guests in attendance agreed to support this activity through provision of documents (including civil guides, technical documents and reports already in circulation), as well as reviewing, or providing comments to the AVT-225 output.

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Annex E − DECISION CHART FOR MILITARY PLATFORM CERTIFICATION

Platform may be certified to Fuel rejected for use START use candidate fuel with Conditionally Yes on platform. restrictions.

Identify fuel specifications Does the TA certify (ASTM, Def Stan, Mil platform for use of fuel specification, etc.) that the based on previous candidate fuel is approved results? under (if any).

No/Not Sure

Obtain Additional Information

Figure E-1: Decision Chart for Military Platform Certification.

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Annex F − PETROLEUM COMMITTEE VISION ON FUTURE FUELS

The following is an Annex containing a copy of an external document.

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27 March 2014 NOTICE AC/112(NFLWG)(EAPC)D(2014)0001 Silence Procedure ends: 4 Apr 2014 12:00

PETROLEUM COMMITTEE (PC) NATO FUELS ANND LUBRICANTS WORKING GROUP (NFLWG)

PETROLEUM COMMITTEE VISION ON FUTURE FUELS

Note by the Staff Officer

References: (a) AC/112(NFLWG)(EAPC)DS(2013)0001, paragraph 8 (b) AC/112(NFLWG)(EAPC)N(2014)0003, MULTIREF, dated 29 January 2014

1. Further to reference (a), a revised Petroleum Committee Vision on Future Fuels at Annex 1has been prepared by a Task Force established as directed by the NATO Fuels and Lubricants Working Group. The revised Petroleum Committee Vision on Future Fuels is now being forwarded to nations for approval and for agreement to declassify the document from NATO/EAPC classified to NATO non-classified so that it can be published on the NATO website and be released to industry. This is of a particular interest in our on- going work with NATO’s Science and Technology Organization and the work conducted on NATO’s Green Defence Framework.

2. Unless the Staff Officer is notified to the contrary by 1200 hrs on Friday, 4 April 2014, the revised Petroleum Committee Vision on Future Fuels will be assumed, under the silence procedure, to have been approved and being agreed to be declassified from NATO/EAPC Unclassified to NATO non-classified.

(Signed) P. VAN EXEM

1 Annex 2 Appendices

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THE PETROLEUM COMMITTEE VISION ON FUTURE FUELS

BACKGROUND

1. The military is dependent on fossil fuels for propulsion, but climate change, the finite nature of oil reserves, and concerns over political security in oil producing regions means that availability, affordability, and environmental acceptability will be an important issue in the long-term. There is no change expected in the implementation of the NATO Single Fuel Policy (SFP) which will remain extant for all existing and future land-based aircraft, vehicles, and equipment. It is envisaged that oil production and demand will start to peak soon after 2020, but it can be assumed that petroleum-based fuels will be available for a long time to come.

2. As a substitute for today’s petroleum based fuels, some practical choices include fuels derived from biomass, natural gas, and waste feedstocks due to availability and/or potential greenhouse gas offset.

NEAR-TERM OPTIONS

3. While biodiesels could potentially be widely adopted by the military, the quality of the product is variable and highly dependent on the feedstock. Problems such as limited storage stability, water separability, low temperature behaviour, and sensitivity to microbiological growth are of great concern. Biodiesel blended up to 5-10 % v/v with conventional diesel fuel appears to be the likely way ahead for ground equipment during peacetime, but the SFP capability remains paramount. Today, there are synthetic fuels, for instance GTL and HVO, in the market that fully comply with the current range of fuel specifications but their availability is limited. It is expected that the oil companies are to target synthetic diesel fuel initially as the lowest risk sector.

4. Drop-in replacement fuels: efforts continue to certify and approve the use of drop- in alternative fuels. Fischer Tropsch (FT) and Hydroprocessed Esters and Fatty Acids (HEFA) fuels are already certified and approved for inclusion in some commercial and military aviation fuel specifications. These are blends of synthetic and conventionally derived petroleum fuels. Technologies currently undergoing approval are Alcohol to Jet, Direct Sugar to Hydrocarbons, Pyrolysis and Hydroprocessed Depolymerised Cellulosic products which will likely become available for certification as possible blending components for use in military and commercial fuels.

MEDIUM-TERM OPTIONS

5. In the medium-term (10 to 20 years), fuels derived from synthetic crude made via the FT and HEFA processes will become more widely available on the market. The synthetic crude produced by the FT and HEFA processes can be tailored (i.e. its

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composition like aromatics and properties like lubricity can be adjusted) to produce fuels to meet marine, diesel, and aviation engine requirements/specifications. These fuels are stable, have improved combustion characteristics, and would be excellent for military use.

6. In the medium-term many new processes will come into use: Alcohol to Jet fuel, pyrolysis of waste materials, direct sugar to hydrocarbon conversions, depolymerisation of plastics and other materials, microbial conversion of waste and bio-mass, catalytic hydrothermalysis of esters and fatty acids, and the production of synthetic aromatic materials. The certification of synthetically produced aromatic materials will facilitate the use of a 100% fully synthetic fuel containing both straight chain hydrocarbons and aromatics. The mid-term will continue to look down the pathway towards commercialization of the technologies that have been approved for use.

LONG-TERM OPTIONS

7. In the long-term (beyond 20 years), there will be a wide variety of technologies available. The Fischer-Tropsch process could be used to produce synthetic fuels from a wide variety of feedstocks; this is referred to as XTL (anything-to-liquid) fuel. Extensive world coal and gas reserves would offer a feedstock to produce these XTL fuels assuring a long-term security of supply. These coal based synthetic fuels would have a very poor carbon balance when compared to a biomass feedstock which can offer an excellent carbon offset. There are logistic concerns about gathering sufficient biomass and other concerns about energy crops displacing food production or causing rainforest deforestation which could limit the use of biomass. There are other biomass processes that may become commercially viable such as biomass from algae but considerably more research is required. If sufficient XTL fuel becomes available in the long-term it could present an excellent opportunity to establish a single synthetic military fuel for air, land, and sea.

8. Hydrogen is often presented as the ultimate fuel, but it is unlikely to become a serious contender for many years. There is no hydrogen infrastructure as yet, there are technical and energy efficiency issues in storage and distribution. Moreover, the demonstrated advantages of hydrogen powered fuel cell vehicles have not yet appeared on the commercial market. Even if all of these problems were to be solved, there are still military barriers in using hydrogen as a fuel, especially in remote war zones, for jet aircraft, or in legacy equipment. However, developments are on-going in this field and the use of hydrogen for fuel cell systems could become an ultimate reality such as portable communication systems that run on a fuel cell.

RECOMMENDED ACTION

9. While we can postulate the future fuels vision based on the evidence available today, in reality there are numerous known and unknown factors that can influence the future vision. It should be noted that the military is a rather small user of petroleum products and, therefore, that its influence on future developments is limited. Therefore, it

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ANNEX 1 AC/112(NFLWG)(EAPC)D(2014)0001 is vital that NATO nations, the PC (through its sub-ordinate bodies) and the Science and Technology Organization/Applied Vehicle Technology (STO/AVT) engage in close partnership with the Original Equipment Manufacturers (OEMs) and the oil manufacturers to develop future equipment and fuel specifications that are congruent with all the prevailing and forthcoming performance and environmental requirements. While liquid hydrocarbons, synthesised from different feedstocks can be available indefinitely, the issues of cost, security of supply, and the effect on the environment remain paramount. Thus our endeavours should be targeted at improving equipment performance by making it more energy efficient and compliant with the use of alternative fuels. For all land-based military equipment, compliance with the NATO SFP remains unchanged.

STRANDS FOR INVESTIGATION

BACKGROUND

10. The PC was asked by the Science & Technology Organisation to provide a “NATO Future Fuel Vision”1 in order to help the Applied Vehicle Technology Working Group studying the Impact of Changing Fuel on Land, Sea and Air Vehicles (AVT-159) in conducting the required investigations. The programme of work of AVT-159 would also include further investigating on the impact of very high sulphur fuels on military equipment using advanced emission reduction technologies. The NATO Fuels and Lubricants Working Group developed the vision for future fuels which was presented to the AVT-159 Working Group at their Spring 2007 meeting in Firenze, Italy. The vision defines the near, medium, and long-term options for petroleum-based and alternative fuels. Given the expected service life of current and future military equipment and the requirement for interoperability, it is expected that the military will be dependent on fossil fuels for the next thirty years. While the SFP will remain paramount for decades to come, new synthetic fuels will enter the market. At the 2007 NF&LWG meeting2 it was decided that a more detailed Future Fuels Vision would be prepared on behalf of AVT-159 in order to assist them in establishing a future work programme. The work of AVT-159 was finalized in 2012 and a report was published “Technological and Operational Challenges Associated with B10 and B20 Biodiesel blended Fuels on Land-based Vehicles”. A new project was set up in order to investigate and study “Future Technological and Operational Challenges connected with Synthetic Fuels”. As of 1st January 2014 a new AVT-225 WG was formed to conduct the study.

1 DPP(LOG)(2007)0036(FUELS) and EAPC(NPC-NFLWG)DS(2007)0001, Annex 7 2 EAPC(NPC-NFLWG)DS(2007)0001, paragraph 7

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AIM

11. The aim is to provide to the AVT-225 WG technical information and guidance on future fuels in order for them to elaborate a programme of work to investigate and to propose solutions to:

11.1 the impact of synthetic drop-in fuels on fuel specifications and properties;

11.2 the impact of synthetic fuel blends on vehicle/equipment hardware and on the handling of these fuels (i.e. operational impact);

NEAR-TERM (NEXT 10 YEARS)

12. The most practical near-term option is the use of drop in hydrocarbon alternative fuels blended with conventional fossil fuels.

13. International guidelines for qualification of fuels and additives specify that all fuel properties should be evaluated. The fuel properties to be considered as a minimum when investigating the impact of future fuels on military equipment are listed at Appendix 1 of Annex 1.

14. Further to fuel properties following aspects are to be considered:

14.1 effect on vehicles equipped with advanced emission reduction technologies (EURO 5, EURO 6, EPA 07, EPA 2010, etc.). This could include the adverse effect of trace elements such as sodium, potassium, and magnesium.

14.2 effect on over all engine performance.

14.3 effect on flexible fuel storage tanks as part of the Tactical Fuel Handling Equipment (TFHE) Modular Concept (STANAG 4605/AFLP-7).

MEDIUM-TERM (NEXT 10-20 YEARS)

15. For the medium-term synthetic fuels derived from natural gas, so-called gas to liquid fuels (GTL) and second generation bio-diesels will become available. These fuels are produced through a synthetic production process (Fischer-Tropsch) or by hydroprocessing and likely to be blended with conventional fossil fuels. The impact of these synthetic fuels on the SFP becomes important.

16. International guidelines for qualification of fuels and additives specify that all fuel properties should be evaluated. The fuel properties to be considered as a minimum when investigating the impact of future fuels on military equipment are listed at Appendix 1 of Annex 1.

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17. Further to fuel properties following aspects are to be considered:

17.1 effect on vehicles equipped with advanced emission reduction technologies.

17.2 effect on all over engine performance.

17.3 effect on flexible fuel storage tanks as part of the TFHE Modular Concept (STANAG 4605/AFLP-7).

17.4 effect on vehicle stability due to changing density properties of fuels.

LONG–TERM (BEYOND 20 YEARS)

18. For the long-term synthetic fuels using a wider variety of feedstock, so-called anything to liquid fuels (XTL), and second generation bio-fuels will continue to enter the market as a neat product or as a blending component to fossil fuels.

19. International guidelines for qualification of fuels and additives specify that all fuel properties should be evaluated. The great variety of feedstocks and production processes will result in a great variety in chemical composition. Detailed research on chemical composition must be considered. The fuel properties to be considered as a minimum when investigating the impact of future fuels on military equipment are listed at Appendix 1 of Annex 1.

20. Further to fuel properties following aspects are to be considered:

20.1 effect on vehicles equipped with advanced emission reduction technologies.

20.2 effect on all over engine performance and future engine technologies.

20.3 effect on flexible fuel storage tanks as part of the TFHE Modular Concept (STANAG 4605/AFLP-7).

ADDITIVES

21. At all stages the possible investigation of additives must be considered. These investigations should only be exercised when the properties of the future fuels cannot meet the NATO requirements. The involved properties / related additives are listed in Appendix 1 of Annex 1.

RECOMMENDED ACTIONS

22. Consider the PC Vision on Future Fuels at all stages of the work programme.

23. Consider the compatibility with the SFP at all stages of the work programme.

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ANNEX 1 AC/112(NFLWG)(EAPC)D(2014)0001

24. Consider future fuel characteristics when developing the future work programme.

25. Consider the compatibility with current and future equipment at all stages of the work programme.

26. The PC Vision on Future Fuels is a living document which needs regular updates and therefore the STO and the PC will need to continue their liaison activities.

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APPENDIX 1 ANNEX 1 AC/112(NFLWG)(EAPC)D(2014)0001

FUEL PROPERTIES TO BE CONSIDERED AS A MINIMUM WHEN INVESTIGATING THE IMPACT OF FUTURE FUELS ON MILITARY EQUIPMENT

FUEL PROPERTIES NEAR-TERM MID-TERM LONG-TERM

First generation of bio- Synthetic Fuels made diesel derived from via Fisher Tropsch Synthetic fuels from vegetable oils, blended process or a wide variety of Fuel types expected with fossil fuel hydroprocessing feedstocks (XTL) as (HEFA), likely to be pure product or blended with fossil fuel blended Composition Acidity X Aromatics X X X Fame Composition X Water Content X X X Sulphur content X Oxygen content X Volatility Distillation X X X Flash Point X X X Density X X X Fluidity Viscosity X X X CP, PP, CFPP X Filter blocking tendency X X Combustion Heat of Combustion/Specific energy X X X Carbon residue X X Cetane Number X X X Naphthalenes X Stability Thermal stability X X Storage Stability X X X Oxidation stability X X

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FUEL PROPERTIES NEAR-TERM MID-TERM LONG-TERM

First generation of bio- Synthetic Fuels made diesel derived from via Fisher Tropsch Synthetic fuels from vegetable oils, blended process or hydro- a wide variety of Fuel types expected with fossil fuel processing (HEFA), feedstocks (XTL) as likely to be blended with pure product or fossil fuel blended Miscellaneous

Water Separation tendency X X X Elastomer and metal compatibility X X X Microbial effects X X X Solvency X X X Lubricity X X Corrosion X X X Effects on filter monitoring/coalescer systems Not applicable X Trace metals Trace metals from Biodiesel production process and the feedstock Alkali Na & K Alkaline Ca & Mg Phosphorus X Trace metals from refinery processing involving catalysts (Al, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Pd, Pt, Sn, Sr, Ti, V, Zn) X X Additives Cetane improvers X X X Lubricity improvers X X Cold flow improvers X X X

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APPENDIX 2 ANNEX 1 AC/112(NFLWG)(EAPC)D(2014)0001

GLOSSARY OF COMMONLY USED DEFINITIONS OF ALTERNATIVE FUELS

Term Definition ATJ – Alcohol to Alcohol to Jet Fuel is a process were sugars extracted from cell-based material like Jet Fuel wood, paper or grass or fermented to alcohols and the processed into aviation turbine fuel. Alternative fuels Non-conventional fuels (including biofuels such as biodiesel, ethanol, hydrogen, electricity-storing batteries, fuel cells), often with improved environmental footprints, that are derived from non-petroleum sources. ASTM D1655 Standard Specification for Aviation Turbine Fuels ASTM D7566 Standard Specification for Aviation Turbine Fuels Containing Synthesized Hydrocarbons ASTM Originally known as the American Society for Testing and Materials (ASTM). A International voluntary standards development organization. ASTM International specifications are used for the certification of jet fuel. Biofuel Renewable fuels derived from biological materials that can be regenerated. This distinguishes them from fossil fuels, which are considered nonrenewable. Examples of biofuels for ground transport are ethanol, methanol, and biodiesel. Biofuels compatible with aviation can include Fischer-Tropsch or hydrotreated jet fuel made from plant or animal sources or hydrocarbons synthesized by genetically modified organisms (synthetic biology). Biomass Biomass includes plant or animal matter that can be converted into fibers or other industrial chemicals, including biofuels. Conversion of biomass can be achieved by different methods which are broadly classifies into: thermal, chemical and biochemical methods. BTL Biomass to Liquid (BTL) is the process to produce liquid biofuels from biomass, usually referring to gasification and Fischer-Tropsch (FT) synthesis. Commercial A coalition of airlines, aircraft and engine manufacturers, energy producers, Aviation researchers, international participants and U.S. government agencies. Together these Alternative Fuels stakeholders are leading the development and deployment of alternative jet fuels for Initiative (CAAFI) commercial aviation. Certification Refers to the confirmation of certain characteristics of an object, person, or organization. Coal/Biomass to A process by which coal and biomass are turned into synthetic hydrocarbons, often via Liquid (fuels) Fischer-Tropsch synthesis. Coal to Liquid A process referred to as coal liquefaction – allows coal to be utilized as an alternative to (fuels) oil. There are two different methods for converting coal into liquid fuels:

Direct liquefaction works by dissolving the coal in a solvent at high temperature and pressure. This process is highly efficient, but the liquid products require further refining to achieve high grade fuel characteristics.

Indirect liquefaction gasifies the coal to form a ‘syngas’ (a mixture of hydrogen and carbon monoxide). The syngas is then condensed over a catalyst – the ‘Fischer- Tropsch’ process – to produce high quality, ultra-clean products. Crude oil A mixture of hydrocarbons that exists in the liquid phase in natural underground reservoirs and remains liquid at atmospheric pressure after passing through surface- separating facilities. Defense Logistics The U.S. Department of Defense's Logistics combat support agency, provides Agency (DLA) worldwide logistics support to the military services as well as several civilian agencies and foreign countries.

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Term Definition Drop-in jet fuel A substitute for conventional jet fuel, that is completely interchangeable and compatible blend with conventional jet fuel when blended with conventional jet fuel. A drop-in fuel blend does not require adaptation of the aircraft/engine fuel system or the fuel distribution network, and can be used “as is” on currently flying turbine-powered aircraft. Drop-in neat jet A substitute for conventional jet fuel, that is completely interchangeable and compatible fuel with conventional jet fuel. A drop-in neat fuel does not require adaptation of the aircraft/engine fuel system or the fuel distribution network, and can be used “as is” on currently flying turbine-powered aircraft in pure form and/or blended in any amount with other drop-in neat, drop-in blend, or conventional jet fuels. DSH – Direct Microbe-catalyzed conversion of sugar to farnesene and then a combination of Sugar to hydroprocessing and separation operation to produce farnesene. Hydrocarbon EIA Energy U.S. Department of Energy's Energy Information Administration provides official energy Information analysis, information and statistics. Administration Fatty Acid Methyl More commonly referred to as biodiesel. This is traditional biodiesel, produced by Ester (FAME) processing raw vegetable oil or animal fats through a chemical process called transesterification. While it is used in diesel surface vehicles, FAME is not considered a suitable "drop in" fuel for jet aircraft or naval ships. Fatty acids Organic acids from which fats and oils are made. These can be used as feedstocks for HRJ fuels. Feedstock Raw material required for an industrial process and more specifically for the production of an alternative fuel. Fischer-Tropsch Is a catalyzed chemical reaction in which synthesis gas, a mixture of carbon monoxide and hydrogen, is converted into liquid hydrocarbons of various forms. Named for German researchers Franz Fischer and Hans Tropsch. Fossil Fuels Any naturally occurring organic fuel formed in the Earth’s crust, such as petroleum, coal and natural gas. Formed by fossilization of organic material deposited by decaying plant/animal matter. FRJ Fermented A biofuel created by a synthetic biology process in which metabolic processes involved Renewable Jet in fermentation have been co-opted by genetically modifying organisms to produce hydrocarbons in place of ethanol. FT Fuel Fuel produced by the Fischer-Tropsch method. Gasification It is a manufacturing process that converts any material containing carbon—such as coal, petroleum coke (petcoke), or biomass—into synthesis gas (syngas). GTL- Gas To Gas To Liquid is a process to produce liquid synthetic hydrocarbons usually through Liquid Fisher-Tropsch synthesis. HRJ Hydrotreated Renewable Jet fuel. Hydrocarbons Substances containing only hydrogen and carbon. Fossil fuels are made up of hydrocarbons. As are synthetic drop-in jet fuels. Hydroprocessing Any of several chemical engineering processes including hydrogenation, hydrocracking and hydrotreating, especially as part of oil refining. Hydrotreating Process that removes sulfur and nitrogen in petroleum refineries to improve the quality of gasoline, jet fuels and diesel fuel. HDC -- Conversion of biomass to bio-crude using a thermo catalytic conversion process and Hydrotreated hydrotreating and distillation to produce fuel blend components Depolymerized Cellulosic

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Term Definition HEFA – Fuel produced from mono-, di- and triglycerides, free fatty acids and fatty acid esters Hydroprocessed from plant, algae oils or animal fats that have been hydroprocessed to remove Esters and Fatty essentially all oxygen. This is sometimes referred to as Hydroprocessed Renewable Acids fuels Diesel (HRD). HVO – Hydrogenated Vegetable Oil is a biofuel produced by hydrotreating vegetable oil or Hydrogenated animal fat Vegetable Oil IATA International Industry group operating as a vehicle for inter-airline cooperation in promoting safe, Air Transport reliable, secure and economical air services - for the benefit of the world's consumers. Association ICAO An organization of the United Nations responsible for cooperative regulation of International Civil international civil aviation. Aviation Organization Jet A Jet A is a kerosene type of fuel, produced to an ASTM International specification and normally only available in the U.S.A. It has the same flash point as Jet A-1 but a higher freeze point maximum (-40°C). It is supplied against the ASTM D1655 (Jet A) specification. Jet A-1 Jet A-1 is a kerosene grade of fuel suitable for most turbine engine aircraft. It has a flash point minimum of 38°C and a freeze point maximum of -47°C. Jet Fuel The term includes kerosene-type jet fuel and naphtha-type jet fuel. Kerosene-type jet fuel is used primarily for commercial turbojet and turboprop aircraft engines. Naphtha- type jet fuel has been largely phased out but was used primarily for military turbojet and turboprop aircraft engines LCA Life cycle analyses (LCA) looks at the whole picture of how a fuel is made, from "cradle to grave." In the case of biofuels generally refers to greenhouse gas emissions or CO2 emissions from initiation of feedstock production to combustion of the fuel in a vehicle. Liquefaction A process by which natural gas is converted into a liquid. Also a process by which coal is converted into synthetic fuels. Can also refer to biomass liquefaction at high pressure and moderate temperature that result in the production of low-oxygen bio-oil, which can be used as, or further refined into, hydrocarbon fuel. National Air A trade organization representing aviation service businesses such as fixed base Transportation operators, charter providers, aircraft management companies including those supporting Association fractional shareholders, maintenance and repair organizations, flight training and airline service companies. Promotes safety and the success of aviation service businesses. NERD NERD is Non-Esterified Renewable Diesel. There are several varieties of this type of biodiesel, also known as renewable diesel. The most advanced of these is produced through hydrotreating—the same process that is already used in today’s petroleum refineries. HRJ is an example of a NERD fuel. OEM An original equipment manufacturer, or OEM, manufactures products or components which are purchased by a purchasing company and retailed under the purchasing company's brand name. OEM refers to the company that originally manufactured the product. Particulate matter The term for a mixture of solid particles and liquid droplets found in the air resulting from fuel combustion. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small, they can only be detected using an electron microscope. PM has health consequences when inhaled and is regulated by the EPA.

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Term Definition Petroleum A generic term applied to oil and oil products in all forms, such as crude oil, lease condensate, unfinished oils, petroleum products, natural gas plant liquids, and non- hydrocarbon compounds blended into finished petroleum products. Pyrolysis Production of bio-oil from biomass by heating at low pressure and high temperature in the absence of oxygen. Qualification (of Qualification processes are used by specification-writing organizations such as ASTM fuel) International to develop new fuel specifications, or to revise existing specifications, to add a new alternative fuel. These qualification processes will include a technical evaluation of the fuel followed by development of the specification requirements and criteria. Refinery A production facility composed of a group of chemical engineering unit processes and unit operations refining certain materials or converting raw material into products of value. Renewable Energy generated from natural resources such as sunlight, wind, rain, tides, and Energy geothermal heat, which are renewable (naturally replenished). Synthesis gas A mixture of carbon monoxide, carbon dioxide and hydrogen created by gasification of high carbon-content materials such as coal or biomass. Gasification to form synthesis gas is a part of the Fischer-Tropsch process for producing synthetic hydrocarbons. Synthetic fuel Liquid fuel obtained from coal, natural gas, or biomass. Synthetic jet fuel Jet fuel made from non-petroleum sources. When this fuel is a "drop-in" fuel, it is also called synthetic paraffinic kerosene. The specification (ASTM 7566) for synthetic jet fuel for commercial aviation use was passed by the aviation fuels subcommittee of ASTM International, the standards development organization. Synthetic Synthetic jet fuel that has similar characteristics to standard petroleum based jet fuel paraffinic (kerosene). See also "synthetic jet fuel." kerosene Ultra Low Sulfur Refers to fuels from which sulfur has been removed to reduce particulate matter from emissions. Its most prevalent application currently is for diesel. XTL- Any Any Feedstock to Liquid fuels are produced through specialized coversions processes Feedstock to Liquid Fuels Yellow Grease Recycled used cooking oil. Used as a feedstock for biodiesel production.

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STO-TR-AVT-225

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REPORT DOCUMENTATION PAGE

1. Recipient’s Reference 2. Originator’s References 3. Further Reference 4. Security Classification of Document STO-TR-AVT-225 ISBN NATO AC/323(AVT-225)TP/803 978-92-837-2131-4 UNCLASSIFIED RELEASABLE TO PFP, MD, AUS, NZL

5. Originator Science and Technology Organization North Atlantic Treaty Organization BP 25, F-92201 Neuilly-sur-Seine Cedex, France

6. Title Military User’s Guide for the Certification of Aviation Platforms on Synthetic Jet Fuels

7. Presented at/Sponsored by Final Report of the AVT Task Group 225.

8. Author(s)/Editor(s) 9. Date Multiple July 2018

10. Author’s/Editor’s Address 11. Pages Multiple 106

12. Distribution Statement This document is distributed in accordance with NATO Security Regulations and STO policies.

13. Keywords/Descriptors Alternative fuel CGSB-3.24 MIL-DTL-83133 ASTM D7566, D4054, D1766, Def Stan 91-091 MIL-HDBK-510A D1655 Fuel approval Platform certification Biofuel Fuel specifications STANAG 3747 Biojet Jet fuel Synthetic jet fuel

14. Abstract Before any alternative jet fuel containing synthetic components may be delivered to a NATO aircraft, it must first be ascertained that the appropriate clearance documents permitting its use have been obtained. Typically, clearances for using the fuel on a particular platform would be provided jointly by the military fuel Technical Authority and the military platform TA in cooperation with Original Equipment Manufacturers (OEMs). However, a tendency has sometimes been noted where OEMs, who are not as well integrated with the ASTM International approval process for synthetic jet fuels, are seeking elaborate testing of ASTM D7566-approved fuels prior to their introduction in their military platforms. This adds significant cost, time and effort for the individual certification of such platforms when the effort may already be redundant. This user’s guide is intended to assist the platform TA in coming up-to-speed on the subject of synthetic jet fuels, and navigating the question of whether to certify a particular platform with an alternative synthetic jet fuel. This user’s guide is also intended to raise awareness among military OEMs so that they will be more involved in the ASTM D4054 fuel approval process for synthetic fuels meeting the requirements of the ASTM D7566 specification.

STO-TR-AVT-225

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