A Comparative Study on the Prospects of Sustainable Aviation Fuels in Sweden

A comparative study on the prospects of sustainable aviation fuels in Sweden

Daniel Katebi Olle Hoffman Carlsson

Kandidatexamensarbete KTH – Skolan för Industriell Teknik och Management Energiteknik EGI-2020) Bachelor of Science Thesis KTH School of Industrial Engineering and Management Energy Technology EGI-2020 TRITA-ITM-EX 2020:220 SE-100 44 STOCKHOLM

Bachelor of Science Thesis EGI-2020

TRITA-ITM-EX 2020:220

Approved Examiner Supervisor Dilip Khatiwada Dilip Khatiwada Commissioner Contact person

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Sammanfattning Flygplansindustrin behöver röra sig mot en mer hållbar framtid för att nå Europeiska Unionens klimatmål (att nå en klimatneutral ekonomi senast 2050), och under de senaste åren har intresset för hållbara flygplansbränslen ökat markant. I denna rapport sammanställde och jämförde vi olika produktionsvägar och råmaterial utifrån ekonomiskt-, tekniskt- och klimatperspektiv för långsiktig implementation. En litteraturstudie utfördes för att samla information om hållbara flygplansbränslen. Det finns ett flertal sätt att producera hållbara flygplansbränslen och denna rapport jämför tre olika produktionsvägar: Hydroprocessed Esters and Fatty Acids (HEFA), hydrotermisk förvätskning (HTL) och elektrobränslen. Av dessa har enbart HEFA godkänts för användning som flygbränsle (april 2020). Rapporten jämförde även tre olika råmaterial: biomassa från skogen, matlagningsolja samt matavfall ur ett svenskt perspektiv. Jämförelsen utfördes med en Pugh-matris som var baserad på: minskning i växthusgasutsläpp, teknisk mognadsgrad (hur långt i utvecklingen har produktionsväggen kommit), kostnaden för bränslet, effektivitet och potentiell bränslemängd (hur stor del av svenska jetbränslekonsumtionen kan vardera produktionsväg täcka). För att sätta jämförelsen i ett långsiktigt perspektiv vägdes jämförelseparameterna till: potentiell bränslemängd - 30%, minskning i växthusgasutsläpp - 30%, pris – 20%, avkastning – 10% och bränslet mognadsgrad – 10% av total 100 poäng. Studien fann att HTL med biomassa från skogen är lämpligast för en långsiktig implementation, på grund av dess höga potentiella bränslemängd samt ett lågt pris. Om priset för elektrobränslen kan minska genom till exempel statliga subventioner är även det ett intressant alternativ framförallt på grund av väldigt låga växthusgasutsläpp.

Abstract The aviation industry needs to move towards a more sustainable future to achieve the climate goals set forth by the European Union (to reach a climate neutral economy by 2050), and in the recent past the interest in sustainable jet fuel has increased. In this report we compared different feedstocks and pathways for production of sustainable jet fuels from an economical, technical and environmental perspective for long-term implementation. A literature study was performed to gather data regarding fossil-based jet fuel, feedstocks for jet bio fuels and pathways for producing sustainable jet fuels. There are multiple ways of producing sustainable jet fuel and this report compares three different pathways: Hydroprocessed esters and fatty acids (HEFA), hydrothermal liquefaction (HTL) and electrofuel. Of these pathways, only HEFA has received certification for use as a jet fuel as of April 2020. The report also compared three different feedstocks: forest residues, used cooking oil and food waste. The comparison was done with a Pugh matrix - a criteria-based matrix - and was based on greenhouse gas (GHG) emission reduction, fuel readiness level (what stage of development the pathway is in), fuel production cost, yield and potential fuel output (how much of Sweden’s current jet fuel consumption can potentially be covered by each pathway/feedstock). The relevant data for the comparison was also gathered from the literature study. To put the comparison in a long-term context, the parameters where given a percentage of the total 100 points: potential fuel output – 30%, GHG-e – 30%, price – 20%, Yield – 10% and fuel readiness level – 10%.

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The study found that HTL with forest residues is most suitable for long-term implementation because of a high potential fuel output and low price. If the fuel production price of electrofuels can go down e.g. through government subsidies it would be another suitable alternative due to its massive potential in GHG emission reduction.

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Table of Contents 1 Background ...... 8 1.1 Sustainable aviation fuels ...... 8 2 Thesis goal and scope ...... 9 2.1 System boundary of the thesis ...... 10 3 Literature review ...... 10 3.1 Greenhouse gas (GHG) emissions ...... 10 3.2 Fuel readiness level (FRL) ...... 11 3.3 Conventional jet fuel ...... 13 3.4 Feedstocks ...... 14 3.4.1 Used cooking oil ...... 14 3.4.2 Food Waste ...... 14 3.4.3 Forest Residues ...... 14 3.5 Sustainable aviation fuel production pathways...... 15 3.5.1 Hydroprocessed esters and fatty acids (HEFA) ...... 15 3.5.2 Hydrothermal liquefaction, HTL ...... 16 3.5.3 Electrofuels ...... 18 3.6 Stakeholders involved in the SAF ...... 19 3.7 Policies that affects the parameters ...... 22 3.8 Pugh matrix – tool for comparison of SAF ...... 22 4 Method ...... 23 4.1 Method for comparison – Pugh matrix ...... 23 4.2 Method for calculating the potential fuel output ...... 24 5 Results and conclusion ...... 25 5.1 Potential fuel output ...... 25 5.2 Pugh-matrix ...... 26 5.3 Sensitivity analysis ...... 27 6 Discussion and concluding remarks ...... 32 7 Appendix ...... 33 7.1 Calculations for PFO ...... 33 7.2 Points available in each parameter ...... 33 7.3 Grading ...... 33 8 References ...... 34

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Figures Figure 1: Schematic overview of an exemplified supply for the SAF chain that forms the basis for the well to wake emissions data (de Jong, 2018)...... 11 Figure 2: Schematic overview of the supply for the fossil jet fuel chain that forms the basis for the well to wake emissions data (de Jong, 2018)...... 11 Figure 3: Total emissions from Swedish air travel between 1990 and 2017 (Naturvårdsverket, 2019). Emissions at higher altitudes has greater climate impact than emissions on sea level (height effect) (Transport & Environment, 2018)...... 13 Figure 4: Schematic view of the hydrothermal liquefaction process (de Jong, 2018)...... 17 Figure 5: Example of the production process for electrofuels, (Brynolf S. 2018)...... 18

Tables Table 1: The perspectives with their corresponding parameters...... 10 Table 2: Fuel readiness level table and categorization...... 12 Table 3: Biomass potential for tree trunks and branches and treetops ...... 15 Table 4: View of the stakeholders’ roles during fuel development (FRL process) ...... 21 Table 5: Weighing of the comparison parameters ...... 24 Table 6: Percentage of points based on ranking...... 24 Table 7: Resulting comparison parameters values, corresponding to step 4 in Pugh process algorithm (chapter 4.1)...... 26 Table 8: Resulting comparison objects ranking, corresponding to step 5 in Pugh process algorithm (chapter 4.1)...... 27 Table 9: Resulting comparison matrix, corresponding to step 6 in Pugh process algorithm (chapter 4.1)...... 27 Table 10: Varying the PFO with +20% and -20% for all SAFs. Rows marked in orange have changed scores, none exist in this table...... 28 Table 11: Varying the GHG emissions with +20% and -20% for all SAFs. Rows marked in orange have changed scores...... 29 Table 12: Varying the price with +20% and -20% for all SAFs. Rows marked in orange have changed scores, none exist in this table...... 30 Table 13: Varying the GHG emissions with +20% and -20% for all SAFs. Rows marked in orange have changed scores...... 31

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Nomenclature

• HTL - Hydrothermal liquefaction • HEFA - Hydroprocessed Esters and Fatty Acids • GHG - Greenhouse gas • CAAFI - Commercial aviation alternative fuels initiative • TRL – Technology readiness level • FRL – Fuel readiness level • SAF - Sustainable aviation fuel • SLU - Sveriges lantbruksuniversitet • TWh - Terawatt hour • kWh – kilowatt hour • 푚3푓 - Forest cubic metre, the wood above the trunk • LCA – Life cycle analysis

• mi – input mass in kg

• mo – output mass in kg • η – Efficiency

• ei – input energy

• eo – output energy in MJ • HV – heating value in MJ/kg • ρ – density in kg/m3 3 • ρe – fuel energy density MJ/m • V – Volume in m3

• CO2 – Carbon dioxide

• CO2 -e – carbon dioxide equivalents • GHG-e – greenhouse gas equivalents

• GCO2-e/MJ – Grams of carbon dioxide equivalents per mega Joule • CC – Carbon capture • NGO - non-governmental organization • EU – European Union • HVO - Hydrotreated vegetable oils • RISE – Research Institutes of Sweden • PFO – potential fuel output • UCO – used cooking oil

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1 Background Airplane traffic accounted for 6.3 percent of Sweden’s total carbon dioxide emissions in 2017 (Transportstyrelsen, 2019), and passenger flights abroad has more than doubled since 1990. The direct emissions from the aviation sector in 2017 amounted to about 6 million tons of CO2. (Naturvårdsverket, 2019). The effects on climate change from airplane traffic is greater than the just the effects from CO2 emissions, contrails left by airplanes and nitrogen oxide released at high altitudes also contributes to climate change, however both of these have a short lifespan and are usually gone within minutes or hours, compared to CO2, which has a lifetime of over a hundred years (Transport & Environment, 2018). The major concern regarding climate change for the aviation industry is the greenhouse gas emissions.

Globally the direct emissions from aviation amounted to 915 million tons of CO2 in 2019 (ATAG, 2020) and in the European Union (EU) the direct emissions from the aviation sector amounted to

171 million tons of CO2 in 2016 (EASA, 2020). The European Union has a goal of achieving a climate neutral economy by 2050 (European Commission, 2020). Every economic sector will have different ways of reaching the goal. Cars are already being electrified; however, electrification is unlikely to work for all parts of the transportation sector. Electric airplanes have been flown, in December 2019 a de Havilland Beaver modified with a magniX engine flew a 15-minute test flight (The Washington Post, 2020). Another company, Eviation, are developing a commercial electric airplane, Alice. The airplane has capacity for 9 passengers with a range of 540 nautical miles (1000km) and a cruise speed of 240 knots (444 km/h) (Eviation, 2020). Compared to an Airbus a320neo with capacity for 194 passengers and a range of 6300 km (Airbus, 2020) the efficiency of Alice remains low, both in carrying capacity and in range. It is therefore likely that airplanes will continue to use liquid fuel in the short term, and while increasing the efficiency of airplanes can reduce emissions it cannot eliminate them. It is therefore important to increase understanding of sustainable aviation fuel technologies and to compare them.

1.1 Sustainable aviation fuels There are different ways of producing jet fuel in a sustainable way, most technologies use biomass to produce sustainable aviation fuels (SAF). Another, newer technology called electrofuel use CO2 captured e.g. from sources such as sewage water or the atmosphere combined with hydrogen and electricity to produce SAF (de Jong 2018). The jet fuel that is used today is JET A1, this is a fuel with strict requirements on parameters such as: volumetric energy density, thermal stability, freeze point and viscosity. Because of this, sustainable aviation fuel (SAF) is subjected to tough requirements, every SAF must go through a comprehensive certification procedure that is facilitated by the American society for Testing and Materials, this includes the conversion pathways for the particular SAF production chain (IATA 2015). The first sustainable jet fuel (SAF) received certification in 2009 and since then a growing number of airlines and airports have expressed interest in SAFs. Several airlines have become members of the Sustainable Aviation Fuel User Group (SAFUG), a group which commits itself to using SAFs that significantly reduce GHG emissions and do not compete with food supply (Sustainable Aviation Fuel User Group, 2020).

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2 Thesis goal and scope The purpose of this report is to do a comparison study of sustainable aviation fuels (SAF) from an economic, environmental and technological perspective. This research explores the suitable options and finds out if those options are a long-term viable solution in terms of transitioning to sustainable fuel for commercial aviation and based on the findings give recommendations for long-term replacement of conventional jet fuel. In order to do this comparison, the economic, environmental and technological perspectives will be analysed from the following parameters. To create a comparison for the most viable long-term replacement of conventional jet fuel the different perspectives are also prioritized and weighed. Economical perspective: For a sustainable aviation fuel to compete with existing jet fuels it needs to be competitive in price, hence we compare the fuel production cost of the SAFs. Fuel production cost is defined as the cost of producing 1 litre of fuel [€/litre]. For SAF to be able to compete with fossil-based jet fuel the price is vital, however, it is likely to change drastically in the future. In this comparison analysis the economical perspective and its corresponding parameters will be weighed to 20 % of the comparison. Environmental perspective: To compare the direct climate impact of a SAF we compare greenhouse gas (GHG) emissions, see chapter 3.1 for more details. The more a SAF can replace fossil-based jet fuels the greater the climate impact will be; thus, we also examine the potential fuel output (PFO). We define PFO as the percentage of current Swedish jet fuel demand that can be covered by a SAF. The value of SAF is in large dependant on its environmental benefits. In this comparison analysis the environmental perspective and its corresponding parameters will be weighed to 60 % of the comparison. Technological perspective: To get a measurement of the development stage of a SAF we examine the fuel readiness level (FRL), see chapter 3.2 for more details. As a measure of the efficiency of a technology, the yield is studied. The yield is defined as the input (e.g. feedstock in kg) divided by the output (e.g. fuel in kg). Where in development a technology will be in the future is hard to estimate. In this comparison analysis the technological perspective and it´s corresponding parameters will be weighed to 20 % of the comparison.

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Table 2 summarizes the perspectives and parameters as mentioned above.

Table 1: The perspectives with their corresponding parameters. Perspective Economical Environmental Technological Parameter Fuel production cost GHG emissions Fuel readiness level - Potential fuel Yield output (PFO)

2.1 System boundary of the thesis As mentioned, the study compares different SAFs that can serve as a long-term replacement for conventional jet fuel from different perspectives. The report will be limited to these feedstocks: • Forest residues • Food waste • Used cooking oil, (UCO) These feedstocks have been chosen because of their availability in Sweden. Sweden has 23.6 million hectares of productive woodland, corresponding to roughly 58% of Sweden’s land area (SLU, 2020) and Sweden already has existing infrastructure for recovery of food waste because of regulations forcing municipalities to ensure that it is disposed of or recycled (Avfall Sverige, 2018). From the choose feedstocks the following/corresponding processes for transforming the feedstocks in to fuel will be investigated: • Hydroprocessed esters and fatty acids, (HEFA) • Hydrothermal liquefaction (HTL) • Electrofuel HEFA was chosen because it can use used cooking oil as a feedstock (ATAG, Beginner´s Guide to Sustainable Aviation Fuel, 2017), HTL can use both food waste and forest residues as feedstocks (Gollakota et. al. 2018) and electrofuel is a newer technology that uses electricity, hydrogen and CO2 to create fuel (Brynolf S. 2018).

3 Literature review This section contains the material that have been gathered from the literature study and forms the basis of understanding jet fuel, feedstocks and production pathways for SAF, and how we make their comparison.

3.1 Greenhouse gas (GHG) emissions To compare the climate impact of the SAFs, we compare the greenhouse gas emissions, more specifically, the Well-to-Wake emissions. The Well-to-Wake emissions are defined as the emissions from feedstock cultivation, processing, logistics, conversion to sustainable aviation fuel

(SAF), distribution and end use (de Jong, 2018). This is expressed in grams of co2-e to produce 1

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MJ of energy which sums up the GHG emissions of a process in to one metric, [grams of CO2- e/MJ] Figure 1 provides an example of Well-to-wake GHG emissions from production and consumption for a SAF.

Figure 1: Schematic overview of an exemplified supply for the SAF chain that forms the basis for the well to wake emissions data (de Jong, 2018).

Figure 2 presents an example of Well-to-Wake GHG emissions from production and consumption for fossil-based jet fuel.

Figure 2: Schematic overview of the supply for the fossil jet fuel chain that forms the basis for the well to wake emissions data (de Jong, 2018). 3.2 Fuel readiness level (FRL) The further a SAF is in development the quicker it can be deployed. Fuel readiness level (FRL) is a classification developed by the Commercial aviation alternative fuels initiative (CAAFI) and was approved by the United Nations International Civil Aviation Organization (ICAO) in 2009 for grading. FRL grades the processes by giving them a level between 1-9, where the levels can be categorized in 3 basic categories, level 1-3 (yellow) technology phase, level 4-7 qualification phase

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(green), level 8-9 deployment phase (blue) (Commercial Aviation Alternative Fuels Initiative (CAAFI), 2020), this is illustrated in Table 2. Table 2: Fuel readiness level table and categorization. level 1-3: technology phase (yellow), level 4-7: qualification phase (green), level 8-9: deployment phase (blue). Source: CAAFI, 2020). (CAAFI, 2020) FRL Description Requirements4 Fuel quantity1

1 Basic principles Feedstock/process principles identified observed and reported 2 Technology concept Feedstock/complete process identified formulated 3 Proof of concept Lab scale fuel sample produced from realistic 500 millilitres production feedstock. Energy balance analysis for initial environmental assessment and validation of basic fuel properties. 4 Preliminary technical System performance and integration studies 37.8 litres evaluation entry criteria/specification properties evaluated (MSFD/D1655/MIL 83133) 5 Process validation Sequential scaling from laboratory to pilot 302.8 litres to plant 851.781 litres 6 Full-scale technical Fitness, fuel properties, rig testing and engine 302.8 litres to evaluation testing2 851.781 litres 7 Fuel approval Fuel class/type listed in international fuel standards3 8 Commercialization Business model validated for production validated airline/military purchase agreements – Facility specific GHG assessment conducted to internationally accepted independent methodology 9 Production capability Full scale plant operational established 1Quantities required for risk mitigation reference 2As referenced in ASTM approved protocols. 3As listed in original equipment manufacturers manuals for aircraft and engines. 4 Color of the column represents the different phases of the FRL, Yellow - technology phase, Green - Qualification phase, Blue - Deployment phase.

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3.3 Conventional jet fuel Conventional jet fuel is derived from crude oil. It consists of many different chemical substances, but the majority consists of hydrocarbons. The composition of the crude oil varies between the deposits (Matar, S. & Hatch, L.F. 2001, 12). Crude oil is created when organic material by the likes of animals and plants are broken down under high pressure and high heat during a long time. Crude oil is refined through different refining processes, such as distilling, to create a mix of hydrocarbons that has the right characteristics in order to be used as jet fuel (U.S. Energy Information Administration, 2018a). Jet A-1 fuel, a common fuel for commercial aviation, has a 3 3 density of ρ = 810 kg/m , a fuel energy density of ρe = 35.06MJ/L = 35.06GJ/m and a heating value of HV = 43.28 MJ/kg(Chevron, 2017).

Figure 3: Total emissions from Swedish air travel between 1990 and 2017 (Naturvårdsverket, 2019). Emissions at higher altitudes has greater climate impact than emissions on sea level (height effect) (Transport & Environment, 2018). Figure 3 shows that domestic flights in Sweden and their respective emissions has not increased since 1990. International flights, however, has increased by 120 percent in the same time frame, resulting in a GHG emissions increase of 43 percent to roughly 10 million carbon dioxide equivalents (CO2-e) per year, including that emissions at higher altitudes has greater climate impact than emissions on sea level (Transport & Environment, 2018). Since 2000 the emissions have stayed relatively still at around 10 million CO2e per year (Naturvårdsverket, 2019). The number of flights by the Swedish population has increased by 3 percent per year over the last 10 years (Naturvårdsverket, 2020), suggesting that emissions from air travel are unlikely to drop without innovation or regulation. The well-to-wake emissions per MJ for jet fuel in the US ranges from 80.7 to 109.3 gCO2-e/MJ and in the EU the range is 80.4-105 80.7 to 109.3 gCO2-e/MJ. The difference in well-to-wake emissions depends on factors such as crude oil quality and processing technique (de Jong, 2018). The average emission per MJ for conventional jet fuel in the EU is 83.8 gCO2-e /MJ. fuel production cost of conventional jet fuel is currently around 0.45 €/litre (ICCT, 2019). Sweden consumes 22.52 thousand barrels of jet fuel per day in 2019 (The -13-

Global Economy, 2020) this corresponds to 8.220 million barrels per year or 1.307 billion litres per year (159 litres in a barrel) or 1.307*106 m3.

3.4 Feedstocks In this section, information gathered regarding feedstocks for bio-jet fuels are presented.

3.4.1 Used cooking oil In Sweden there is regulating laws which requires municipalities to ensure that household waste is transported and recycled or disposed of. The term household waste refers to waste from households and equivalent waste from businesses such as restaurants. (Avfall Sverige, 2018) This set up leads Sweden having a high percentage of waste collecting. No data regarding the amount of used cooking oil (UCO) collected in Sweden has been found, however, Sweden produces around 2 million tons of food waste every year and about 200 thousand tons of this waste is used cooking oil (Nordic Energy, 2019).

3.4.2 Food Waste One of the biggest contributors to landfills in USA is food waste, (Grunders, 2012). This problem does not exist in Sweden, but it demonstrates the importance of food waste management form a different sustainability parameter, namely landfill usage. Sweden annually produces and collects around 1600 thousand tons of food waste (Avfall Sverige, 2018). This food waste is most efficiently turned in to jet fuel through the Hydrothermal liquefaction process (de Jong, 2018).

3.4.3 Forest Residues Sweden has great possibilities for extraction of biomass from forest residues. Forests make up 70 percent of Sweden’s land surface area, with 23.6 million hectares of forest (roughly 58 percent of Sweden’s land area) are productive woodland (SLU 2020). The annual growth is 4.9 푚3푓 (forest cubic metre, the wood above the trunk) per hectare. This translates to roughly 10 500 TWh of energy with an annual growth of 350 TWh. The theoretical maximum available biomass for bio jet fuel production can be set as the annual growth, in reality, it will compete with already existing industries and their needs. The amount of annual harvest for stemwood was roughly 190 TWh, for branches and treetops it was between 7-14 TWh and for tree trunks it was 0.5 TWh (Börjesson et al. 2013). Even though the harvest of tree trunks is low it has great potential (could be positive since it will not compete with existing industries). The amount of biomass potential for branches and treetops and trunks depends on biological, technical and economical restriction levels defined by Skogsstyrelsen (2008). Level 1 means no restrictions at all; level 2 means ecological restrictions and relates to logging residues and ash return to ensure fertile soil. Restriction level 3 includes the previous mentioned ecological restrictions and introduces technical restrictions based on current collection capabilities and restrictions based on economic feasibility. Table 3 below shows the biomass potential for the three different restriction levels (Börjesson et al. 2013).

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Table 1: Biomass potential for tree trunks and branches and treetops (Börjesson et al. 2013). Biomass Level 1 Level 2 Level 3 potential (no (ecological (ecological and (TWh per year) restrictions) restrictions) technical/economical restrictions) Regeneration felling Branches and 36 25 16 treetops Tree trunks 57 34 21 Subtotal 93 59 37 Thinning Branches and 19 13 9 treetops Tree trunks 28 13 8 Subtotal 47 26 17 Total 140 85 54

3.5 Sustainable aviation fuel production pathways In this section of the report, information gathered regarding production pathways for sustainable aviation fuels are presented.

3.5.1 Hydroprocessed esters and fatty acids (HEFA) Hydroprocessed Esters and Fatty Acids (HEFA) can be produced from various kinds of vegetable oils and fats. The finished product is produced from the hydrotreating of oils where the oils are reacted with hydrogen under high pressure in order to remove oxygen. When the oils have saturated with the hydrogen it leaves alkanes. The alkanes then go through an isomerization process (Henningsson, Brewitz, 2019). The HEFA process uses UCO as feedstock and received certification in 2011 (International Renewable Energy Agency (IRENA), 2017). The HEFA process has at the time of writing the highest level of commercialization (Biojet för flyget, 2019). This is in large due to the HEFA process in most aspects resembling the HVO (hydrogenated vegetable oil) process (biofuels for road transportation). The process results in a drop-in fuel which means that this process still depends on conventional jet fuel. The final product has a mix of 50 percent fuel from the HEFA process and 50 percent conventional jet fuel. An analysis by de Jong (2018) presents that GHG emissions for the HEFA process are 28 gCO2/MJ, a sizable reduction in emissions compared to the conventional jet fuel base line of 83,8 gCO2/MJ. The production cost of the HEFA pathway is 0.88 €/liter this is due to the high yield of the HEFA pathway (ICCT, 2019). According to de Jong (2018) the HEFA process has a conversion rate of feedstock to fuel (yield) of 83 percent. Fuel -15-

produced through HEFA has a density of ρ = 775kg/m3, a heating value of HV = 44MJ/kg and a 3 fuel energy density of ρe = 34.1GJ/m (f3 centre). HEFA was given ASTM certification in 2011 (de Jong, 2018) and is therefore allowed to be used as a jet fuel. Given the definition of FRL in chapter 3.2, the fuel readiness level of the HEFA process is set to level 9.

3.5.2 Hydrothermal liquefaction, HTL Development of hydrothermal liquefaction (HTL) started in the 1970s but most projects have been short-term, in-part due to low oil prices and lack of cooperation. HTL can theoretically use any biomass source but with widely varying efficiencies, on the high-end starch has an energy recovery rate of 88 percent and on the low-end lignocelluloses has an efficiency of 30 percent (representing an energy recovery rate of 50 percent). In this report HTL will use food waste and forest residues as feedstock. Because HTL uses wet biomass there is no need to dry it, resulting in energy savings, however, due to corrosion, the plant needs to be built using expensive alloys and the high pressure puts high stress on components resulting in high start-up costs (Toor, Rosendahl, Rudolf, 2011). Hydrothermal liquefaction is a thermochemical conversion of wet biomass into crude oil in a hot, wet and pressurized environment with a catalyst to improve the quality of the product. The biocrude oil is then upgraded into jet fuel using hydrogen. The hydrogen can either be generated on-site from off-gas produced by previous processes and wastewater, or from hydrogen produced off-site using natural gas. Figure 4 shows an overview of the two different production solutions.

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Figure 4: Schematic view of the hydrothermal liquefaction process (de Jong, 2018). According to de Jong (2018), production of jet fuel using forest biomass and HTL had a Well-to- Wake reduction in greenhouse gas emissions of 80 percent compared to conventional jet fuel if the hydrogen required is generated off-site or a reduction of 82 percent if the hydrogen is produced on-site, resulting in GHG emissions of 28 g CO2 per MJ. The life-cycle analysis (LCA) performed

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by Tzanetis, Posada and Ramirez (2017) reported that GHG emissions may be reduced by 85 percent compared to petroleum-based jet fuels. As the efficiency of the HTL process varies between feedstocks so do the price of the resulting jet fuel, ICCT (2019) found that prices for HTL varies between 1.34 € for forest residues to 1.87 € for food waste. The HTL process with forest residues and food waste has a yield of 33 percent (de Jong). HTL is not yet commercially available but there are pilot plants around the world including Sweden, Research Institutes of Sweden (RISE) is currently undertaking a project to test the technology and has built two new HTL testing facilities, the bigger of the two started operating January 14, 2020 and can continuously operate. It operates at temperatures up to 400°C and pressures up to 300 bar (RISE, 2020). Based on the definition of FRL in chapter 3.2, HTL has an FRL of 6.

3.5.3 Electrofuels Electrofuel (or synthetic fuel, e-fuel, power-to-x, Carbon Capture and Utilization) is fuel, e.g. methane, methanol, n-octane or gasoline produced with carbon dioxide, hydrogen and electricity as the primary energy source (Grahn, M. 2014). The hydrogen is produced by electrolysis and the carbon dioxide can be captured from different sources such as the atmosphere or sewage water and lastly the CO2 and hydrogen are combined in a synthetic process. The type of fuel that is produced depends on which synthetic process is used e.g. methane synthesis, methanol synthesis, Fischer-Tropsch synthesis or even new energy carriers such as synthetic fuels made from biomass. The process also generates oxygen and heat as by-products (Brynolf S, 2018). The result is a fuel produced by the waste of already used fuel. Electrofuel can be produced alongside biofuel to increase the total fuel yield by using the excess CO2. An overview of the production process is shown in Figure 5.

Figure 5: Example of the production process for electrofuels, (Brynolf S. 2018).

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The electrofuel process can result in many different types of fuel, for aviation n-octane is especially interesting as it has similar properties to current jet fuel and can therefore be used in existing jet engines with only small modifications required, a so-called drop-in fuel (Goldman, et al. 2018). The GHG emissions of electrofuel are entirely dependent on the emissions of the electricity source. For electrofuel to be competitive in reducing GHG emissions, it is according to Malins (2017) a requirement that the electricity used during the processes is a zero CO2 emitter, even a low carbon energy source of 25 gCO2-e/MJ would result in a disappointing carbon performance (less than 50 percent reduction). If the electricity used is produced by a zero CO2 emitter such as wind power or solar power the CO2 footprint of the electrofuel is 5 gCO2e/MJ or less (Malins, 2017), however, other emissions such as soot particles, nitrogen-oxide, carbon monoxide and unburnt hydrocarbons will still be emitted (Goldman, et al. 2018).

The Swedish energy mix had a CO2 footprint of 13.1 gCO2-e/MJ in 2013 (Energimyndigheten, 2019). The yield of the electrofuel production varies both between fuel and type of fuel synthesis. Brynolf (2018) found that yields vary between 73 percent and 80 percent for methane, methanol, FT-liquids (gasoline, diesel). If electrofuels are produced using the Swedish energy mix and we assume a yield of 76.5 percent (average value for methane, methanol, FT-liquids) the resulting greenhouse gas emissions are 17.1 gCO2 e/MJ. The price per litre for a power-to-liquid jet fuel using Fischer-Tropsch synthesis are 2.40 € (ICCT, 2019). According to Brynolf (2018) the most important factors in the cost of the fuel are the electrolyser, electricity price, the capacity factor of the unit and the lifetime of the electrolyser. The variation in price between different types of electrofuels are lower than the difference between the low and the high prices, suggesting a similar price range for n-octane. Sustainable Transport Forum sub group on advanced biofuels (2017b) compiled and reviewed currently existing and planned electrofuel facilities that included a power-to-gas plant in Denmark with methane as output, two plants in Germany, one that produce hydrogen and the other produce methanol and one in Iceland that produce methanol. We have not been able to find any facilities that produce n-octane or any other drop in fuel, but many of the required technologies have been tested in other contexts (Malins, 2017). According to Sustainable Transport Forum sub group on advanced biofuels (2017a) electrofuels are in the "early innovation stage" of development, giving electrofuel an FRL of 3, as defined in chapter 3.2.

3.5.3.1 Carbon Capture Electrofuel production requires carbon dioxide which can be captured from multiple sources e.g. the atmosphere, sewage water or directly from a power plant. Sweden emits 45 million metric tons of recoverable CO2 per year, however, most of the CO2 emitted is in low concentration (<15 percent). Turning all the recoverable CO2 into fuel would result in 2.5 times the current Swedish fuel demand for all transportation, but it would require 3 times the current Swedish electricity supply. If instead only high concentration of CO2 is used (>90 percent) e.g. CO2 from biofuel production, the fuel yield would be 1.5-2 TWh/year. Important to note is that the costs of capturing carbon are low compared to the production costs of electrofuels and the limiting factor for the amount of carbon that can be captured is the amount of available electricity (Hansson et al. 2017).

3.6 Stakeholders involved in the SAF The findings in this section of the report will used in the discussion section and does not affect the results section.

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The findings in this section of the report will used in the discussion section and does not affect the results. There are different stakeholders that are involved in the development and deployment process of new fuels, they are listed below. Airlines and customers The airlines which are the consumers of the fuel have an important role in this. They must secure their own survival as the market and the travelers demand for sustainability rises. This motivates the airlines to invest more in SAF. As a rule of thumb for each ton of CO2 that airlines save in emissions, they save around 225 US dollars in operational costs. (IATA, Climate change & CORSIA, 2018) Airports and infrastructure, Swedavia is the government owned company that owns and operates the biggest airports in Sweden. They are also a partner in the fly green fund (Swedavia, 2020). The fly green fund is a non-profit non-governmental organization (NGO) that makes it possible for companies and individuals to buy SAF that is then delivered to airports for airlines to buy. The intention is to increase the demand for SAF and expand SAF production in the Nordic countries (Fly green fund, 2020). SAF producers There are several companies and technologies to produce SAF, this creates diversity when it comes to up-scaling. These factors create risks and makes it an uncertain venture to go in to the SAF production business. With risk also comes to opportunity for high rewards, especially if there is governmental support in this transition, that support, if optimally applied can reduce or eliminate the financial risks with these new types of ventures (ICAO, Sustainable aviation fuels guide). Regulators and governments The price of producing an SAF can be higher than that of current conventional jet fuel production. Since the airlines are the consumers of the SAF regulators must steer the market for jet fuel in such a way that the initial stage of the switch from conventional jet fuel to SAF is economically favoring SAF. Regulators and governments define the goals and targets that is necessary to develop a SAF market. This can be done in different ways, see more in the policy section of this report (ICAO, Sustainable aviation fuels guide). Table 4 shows the relevant stakeholders for the different fuel readiness level (FRL) stages.

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Table 2: View of the stakeholders’ roles during fuel development (FRL process) FRL Description Requirements4 Fuel Stakeholder quantity1 1 Basic principles Feedstock/process principles identified Regulators observed and and reported Governments – Grants for reaserch 2 Technology concept Feedstock/complete process identified Regulators formulated Governments + SAF producers 3 Proof of concept Lab scale fuel sample produced from realistic 500 SAF production feedstock. Energy balance analysis millilitres producers + for initial environmental assessment and Governments validation of basic fuel properties. 4 Preliminary technical System performance and integration studies 37.8 litres SAF evaluation entry criteria/specification properties evaluated producers + (MSFD/D1655/MIL 83133) Governments 5 Process validation Sequential scaling from laboratory to pilot plant 302.8 litres SAF to 851.781 producers + litres Governments 6 Full-scale technical Fitness, fuel properties, rig testing and engine 302.8 litres SAF evaluation testing2 to 851.781 producers + litres Governments 7 Fuel approval Fuel class/type listed in international fuel SAF standards3 producers + Governments + Regulators 8 Commercialization Business model validated for production SAF validated airline/military purchase agreements – Facility producers + specific GHG assessment conducted to Airports and internationally accepted independent infrastructure methodology 9 Production capability Full scale plant operational SAF established producers + Airports and infrastructure + Airlines and customers. 1 Quantities required for risk mitigation reference 2 As referenced in ASTM approved protocols. -21-

3 As listed in original equipment manufacturers manuals for aircraft and engines. 4 Color of the column represents the different phases of the FRL, Yellow - technology phase, Green - Qualification phase, Blue - Deployment phase.

3.7 Policies that affects the parameters The findings in this section of the report will used in the discussion section and does not affect the results section. There are certain aspects that can affect the evaluation parameters, namely the policies and regulations. This section of the report mentions some of these aspects and their possible effect on the evaluation parameters and serves as an input for the discussion section of the report. These policies can be viewed from the scope of how the different fuels can be optimized in the future with regards to Swedish conditions. Cost of production and market price The price of a new fuel used in aviation or road transport depends on the production cost of the fuel. But there is also a taxation on aviation travel in Sweden (Skatteverket, 2020). The UN´s aviation body ICAO has made resolutions that has created the common practice among nations to not tax aviation fuel (Hemmings, 2019). This has forced the Swedish regulators to develop a tax model based on the destination instead (Skatteverket, 2020). Such taxation can be differentiated based on for instance, the emissions of the distance travelled. This will thus affect the price for the end user. Potential fuel output (PFO) A very possible way of altering the PFO (thereby increasing the potential fuel output) is via import or export of a feedstock. There is for instance a big import of general waste to Sweden, in 2018 about 3 million tons of waste was imported to Sweden (Naturvårdsverket, 2020). There is also a big global market in trading used cooking oil which has a projected value at 8.8 billion USD by 2026 (Allied Market Research, 2020). By having regulations and policies that favours the trading of feedstock the PFO of a fuel process can be altered. Fuel Reading Level (FRL) The FRL of a given fuel can increased via both governmental and private research and development. Governments can aid in the earlier stages of the development e.g. with basic research using grants and its institutions. In 2017 around 155.5 billion SEK was put into research and development, this includes both private and public spending (SCB, 2019).

3.8 Pugh matrix – tool for comparison of SAF As mentioned previously, this aims to do a comparison study of SAFs and provide a recommendation for promising sustainable fuels in the aviation sector. The Pugh matrix is a decision-making tool used in engineering; it is a systematic way of comparing alternatives based on a set of criteria. A key benefit of the Pugh matrix is its ability to handle many criteria (Burge S, 2009). There are five steps in Pugh process algorithm.

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1. Pick the comparison parameters. Each comparison parameter should be a quantifiable measure.

2. Pick the comparison objects and define a baseline. All comparison objects are compared to the baseline on a one-to-one basis for each parameter.

3. Establish weighing factors for each comparison parameter. Each comparison parameter is given a number of available points which determines the importance of each parameter, more points equal more importance and less points equals less importance.

4. Establish values for the comparison objects for each comparison parameter.

5. Evaluate the results and calculate the final scores. The greatest challenge when using the Pugh matrix is establishing appropriate weighing factors in step 3 as this influences the results and it can be difficult to know which parameter is most important (Lugo, 2012).

4 Method The methods required for completing the goal of a long-term comparison of SAF are presented in this chapter.

4.1 Method for comparison – Pugh matrix The Pugh matrix is described in section 3.8 in the literature review. For the comparison in this thesis a variation of the Pugh matrix will be used, the difference is in how the baseline is used. The comparison objects will not be compared to the baseline on a one-by-one basis but instead, all comparison objects will be compared to the baseline at the same time, this also means that the baseline will get a score. The final score is then evaluated to form recommendations. When used in the context of this report, the following Pugh matrix algorithm is obtained: 1. The comparison parameter is defined in section 2 as fuel production cost, GHG reduction, PFO, Yield and FRL.

2. The comparison objects are HEFA with UCO, HTL with forest residues, HTL with food waste and electrofuel with conventional jet fuel as the baseline.

3. In chapter 2 the perspectives where weighed to: environmental perspective – 60%, economic perspective – 20% and technical perspective – 20% of the total points. The perspectives with two parameters split the percentage equally. This translates into the following points for each parameter (Total points maximum is 100 points).

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Table 3: Weighing of the comparison parameters Points for Environmental perspective (60 %)1 parameter PFO 30 GHG 30

Points for Economic perspective (20 %)1 parameter Price 20

Points for Technical perspective (20 %)1 parameter Yield 10 FRL 10 1- See chapter 2 for more information regarding the weighing.

4. To obtain the values for each comparison parameter, data is retrieved from the literature study. PFO is calculated using data from the literature study and the method described in chapter 4.2. The comparison objects are then ranked based on the gathered data.

5. Points are given to each comparison object based on the points of the parameter multiplied with the percentage corresponding to the ranking of that comparison object. The percentages for each placement are presented in Table 6. If multiple comparison objects get the same ranking, they all get the average percentage of their combined ranking percentage. Table 4: Percentage of points based on ranking. Ranking Percentage 1st 40% 2nd 30% 3rd 15% 4th 10% 5th 5% 6. The results are evaluated in a matrix.

4.2 Method for calculating the potential fuel output To get a better understanding of a production pathway’s potential we calculate an estimate of the percentage of the current Swedish jet fuel demand that can be covered by that pathway, we define this as the potential fuel output (PFO). To calculate the PFO we divide the produced jet fuel volume for a SAF with Sweden’s current jet fuel demand. The volume is calculated using the energy of the output fuel. The production input is either expressed as mass mi [kg] or as energy ei [J], therefore, two ways of calculating the output energy is needed.

If the input is expressed as a mass, multiply the input mass mi with the yield 휂 of the process to get the mass of the fuel output mo [kg]

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푚표 = 푚푖휂. Equation 1

To convert the output mass to output energy eo [MJ], multiply it with the heating value HV [MJ/kg]

푒표 = 푚표퐻푉. Equation 2

If input is expressed as energy instead of mass, multiply the input energy ei with the yield 휂 of the process to get the output energy

푒표 = 푒푖휂. 3 The output volume V [m ] is then calculated by dividing the output energy eo with the fuel energy density ρe

푒0 푉 = . Equation 3 ρ푒 To get the PFO, divide the output fuel volume with the current Swedish jet fuel consumption in (1.307*106m3) (chapter 3.3) and multiply with 100 to express it as a percentage. 푉 푃퐹푂 = 6 ∗ 100 1.307 ∗ 10 Equation 4

5 Results and conclusion

5.1 Potential fuel output In this section, we present our results for the estimation of the potential fuel output using the method described in chapter 4.2 with data from the literature study. To calculate PFO we need the production input (feedstock or CO2 depending on the production pathway) expressed either as a mass mi [kg] or an energy ei [J], the production pathways efficiency η and the fuel energy density

ρe.

The fuel energy density ρe of jet fuel produced through HEFA is ρe = 34.1GJ/m3 and the yield η for HEFA is η = 0.83, heating value HV = 44MJ/kg (chapter 3.5.1)and we assume all used cooking 6 oil in Sweden (200 000 tons per year, mi = 200*10 kg, chapter 3.4.1) is used for fuel production.

For Electrofuel we assume the low-end scenario (carbon/CO2 captured from sources with >90% concentration), ei = 1.75TWh (ei = 6300000GJ) (chapter 3.5.3.1), with a yield of η = 0.765 (chapter 3.5.3). No information regarding the properties of fuel produced as an electrofuel has been found, 3 instead we use the fuel energy density of A-1 jet fuel, ρe =35.06GJ/m (chapter 3.3). To try to mitigate disturbance to existing industries from fuel production through HTL with forest residues we assume only branches, treetops and tree trunks with restriction level 3 are used for fuel production, ei = 54 TWh (ei = 194400000GJ) (chapter 3.4.3, table 3). HTL has a yield of η = 0.33 (chapter 3.5.2). As no fuel energy density of fuel produced by HTL was found, we use the fuel 3 energy density of A-1 jet fuel, ρe =35.06GJ/m (chapter 3.3). For HTL with food waste, we assume 6 all currently collected food waste in Sweden is used for jet fuel production, mi = 1600*10 kg

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(chapter 3.4.2). No heating value for HTL was found, instead we use the heating value for A-1 jet fuel, HV = 43.28MJ/kg (chapter 3.3). We obtained the following results: • HEFA with used cooking oil – 16.4% • Electrofuel – 10.5% • HTL with forest residues – 140% • HTL with food waste – 49.9%

5.2 Pugh-matrix Table 7 presents the results for each SAF and comparison parameter gathered in the report both from the literature study and from the calculations in chapter 5.1. Table 5: Resulting comparison parameters values, corresponding to step 4 in Pugh process algorithm (chapter 4.1). Parameter HEFA, Electrofuel Forest Food Conventional UCO residues, Waste, Jet fuel HTL HTL PFO [percentage of current jet 16.4%1 10.5%1 140%1 49.9%1 100% fuel consumption in Sweden 2019] (Higher is better) GHG [grams of co2 per MJ] 282 17.13 204 204 83,85 (Lower is better) Price of Product [Euro per 0.88€2 2.40 €3 1.34€4 1.87€4 0.45 €5 litre] (Lower is better) Yield [percentage of 83%2 76.50%3 33%4 33%4 - output/input] (Higher is better) FRL [Index] (Higher is better) 92 33 64 64 9 1- Data from section 5.1 2- Data from section 3.5.1 3- Data from section 3.5.3 4- Data from section 3.5.2 5- Data from section 3.3

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Table 8 displays the corresponding rankings based on the data in Table 7. Table 6: Resulting comparison objects ranking, corresponding to step 5 in Pugh process algorithm (chapter 4.1). Forest residues, Food Waste, Conventional Ranking HEFA Electrofuel HTL HTL jet fuel PFO 4 5 1 3 2 GHG 4 1 2 2 5 Price 2 5 3 4 1 Yield 1 2 3 3 5 FRL 1 5 3 3 1

Table 9 shows the points for each SAF and comparison parameter based on the rankings from Table 8. Table 7: Resulting comparison matrix, corresponding to step 6 in Pugh process algorithm (chapter 4.1). Forest Food Waste, Conventional Points HEFA Electrofuel residues, HTL HTL jet fuel PFO 3 1.5 12 4.5 9 GHG 3 12 6.75 6.75 1.5 Price 6 1 3 2 8 Yield 4 3 1.25 1.25 0.5 FRL 3.5 0.5 1.25 1.25 3.5 Total points 19.5 18 24.25 15.75 22.5

Only forest residues with HTL scored higher than conventional jet fuel due to its high PFO and good GHG emission reduction. HTL with food waste scored lower than HTL with forest residues mainly due to a lower PFO. HEFA with used cooking oil scored 19.5 points making it the second best SAF. HEFA’s main drawback is its low PFO even in the exaggerated scenario used in this report, but it is already approved for use as jet fuel resulting in the highest FRL and the lowest price of all SAF compared. Electrofuel scored the second lowest due to its low PFO and high price. The electrofuel PFO is based on carbon captured from high concentration sources only.

5.3 Sensitivity analysis A sensitivity analysis was performed to investigate the impact when varying the results from chapter 5.2. The sensitivity analysis is performed with the one-at-a-time method where the value of one parameter is varied with +20% and –20%, then analyzing how it impacted the result.

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Table 10 presents how the results change when varying the values for PFO for each SAF with +20% and –20%. There is no change in points when varying the PFO values. Table 8: Varying the PFO with +20% and -20% for all SAFs. Rows marked in orange have changed scores, none exist in this table.

Final outcome in points Forest residues, Food Waste, Conventional HEFA Electrofuel HTL HTL jet fuel No variation1 19.5 18 24.25 15.75 22.5

Comparison object HEFA, Food Waste, where PFO is new Electrofuel, Forest residue, HTL, new Conventional, varied score new score HTL, new score score new score HEFA2 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5

Electrofuel3 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5

Forest residue with HTL4 PFO +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5

Food Waste with HTL5 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5

Conventional jet fuel6 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5 1 - No variation, same points as in Table 8.

2 - Varying PFO values for HEFA with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

3 - Varying PFO values for electrofuel with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

4 - Varying PFO values for HTL with forest residues with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

5 - Varying PFO values for HTL with food waste with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

6 - Varying PFO values for conventional jet fuel with +20% and -20% whilst keeping all other SAF values constant.

In Table 11, the new points when varying the GHG values with +20% and –20% for each SAF is presented. Rows marked in orange indicate change, as can be seen in Table 11 increasing

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electrofuels GHG emission with +20% results in new total points. Varying HTL (forest residues and food waste) with +20% and –20% both change the result.

Table 9: Varying the GHG emissions with +20% and -20% for all SAFs. Rows marked in orange have changed scores. Final outcome in points Food Forest Waste, Conventional Jet HEFA Electrofuel residue, HTL HTL fuel No variation1 19.5 18 24.25 15.75 22.5

Forest Food Comparison residue, Waste,

object where HEFA, new Electrofuel, HTL, new HTL, new Conventional jet GHG is varied score new score score score fuel, new score HEFA2 20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5

Electrofuel3 20% 19.5 10.5 28 19.5 22.5 -20% 19.5 18 24.25 15.75 22.5

Forest residue, HTL4 GHG 20% 19.5 18 22 18 22.5 -20% 19.5 15 29.5 13.5 22.5

Food Waste, HTL5 20% 19.5 18 26.5 13.5 22.5 -20% 19.5 15 22 21 22.5

Conventional Jet fuel6 20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5 1 - No variation, same points as in Table 8.

2 - Varying GHG values for HEFA with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

3 - Varying GHG values for electrofuel with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

4 - Varying GHG values for HTL with forest residues with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

5 - Varying GHG values for HTL with food waste with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

6 - Varying PFO values for conventional jet fuel with +20% and -20% whilst keeping all other SAF values constant.

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Table 12 displays the outcome when varying the price of production with +20% and –20% for each SAF, there is no change in outcome.

Table 10: Varying the price with +20% and -20% for all SAFs. Rows marked in orange have changed scores, none exist in this table. Final outcome in points Food Forest Waste, Conventional HEFA Electrofuel residue, HTL HTL Jet fuel No variation1 19.5 18 24.25 15.75 22.5

Comparison object Forest Food where price of residue, Waste, production is HEFA, new Electrofuel, HTL, new HTL, new Conventional jet varied score new score score score fuel, new score HEFA2 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5

Electrofuel3 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5

Forest residue, HTL4 Price of +20% 19.5 18 24.25 15.75 22.5 production -20% 19.5 18 24.25 15.75 22.5

Food Waste, HTL5 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5

Conventional Jet fuel6 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5 1 - No variation, same points as in Table 8. 2 - Varying price of production values for HEFA with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

3 - Varying price of production values for electrofuel with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant. 4 - Varying price of production values for HTL with forest residues with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

5 - Varying price of production values for HTL with food waste with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

6 - Varying price of production values for conventional jet fuel with +20% and -20% whilst keeping all other SAF values constant.

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Table 13 shows the outcome when varying the yield with +20% and –20% for each SAF. Rows marked in orange shows change. HEFA varied with –20%, electrofuel varied with +20% and HTL (forest residues and food waste) varied with both +20% and –20% results in changes to the final points. Final outcome in points Table 11: Varying the GHG emissions with +20% and -20% for all SAFs. Rows marked in orange have changed scores.

Food Forest Waste, Conventional HEFA Electrofuel residue, HTL HTL Jet fuel No variation1 19.5 18 24.25 15.75 22.5

Forest Food Comparison object residue, Waste, where Yield is HEFA, new Electrofuel, HTL, new HTL, new Conventional jet varied score new score score score fuel, new score HEFA2 +20% 19.5 18 24.25 15.75 22.5 -20% 18.5 19 26.5 13.5 22.5

Electrofuel3 +20% 18.5 19 26.5 13.5 22.5 -20% 19.5 18 24.25 15.75 22.5

Forest residue, HTL4 Yield +20% 18.5 19 26.75 13.25 22.5 -20% 19.5 18 26.25 13.75 22.5

Food Waste, HTL5 +20% 18.5 19 26.25 13.75 22.5 -20% 19.5 18 26.75 13.25 22.5

Conventional Jet fuel6 +20% 19.5 18 24.25 15.75 22.5 -20% 19.5 18 24.25 15.75 22.5 1 - No variation, same points as in Table 8. 2 - Varying yield values for HEFA with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

3 - Varying yield values for electrofuel with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant. 4 - Varying yield values for HTL with forest residues with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

5 - Varying yield values for HTL with food waste with +20% and -20% whilst keeping all other SAF and conventional jet fuel values constant.

6 - Varying yield values for conventional jet fuel with +20% and -20% whilst keeping all other SAF values constant.

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6 Discussion and concluding remarks HEFA with used cooking oil could be implemented as a short-term solution because it is certified for use as a jet fuel today. It is important to mention that the potential fuel output was calculated using all produced cooking oil in Sweden but much less is recovered. Even with that exaggeration HEFA still has a low potential fuel output. The policies section of the report (chapter 3.7) highlights some potential ways of improving the SAFs. Electrofuels are one SAF that has very high potential with government policies e.g. subsidies to the production price, this is due to its exceptional GHG emission reduction potential if it is powered by a zero-carbon emitting renewable energy source. Another main drawback of electrofuel is its low potential fuel output, however, it is important to note that the calculations were based on capturing carbon from high concentration sources and that the limiting factor in capturing carbon is available electricity and not price (Hansson et al. 2017). A variation of +20% and -20% does not have a drastic change on the results, due to high gaps between the values of the parameters for the comparison objects. This indicates robustness in the comparison model. The data regarding density for fuel produced through HEFA was given via the HVO (Hydrotreated vegetable oils) process, which is very similar to the HEFA process, but it has some errors in it when using a different process. A price range for n-octane produced as an electrofuel was not found, however, Brynolf (2018) reports that the variation in price between different fuels produced as electrofuels is low relative to the variation in the price range between high cost and low cost scenarios, as such, the price for n- octane in this report is based on price ranges for other electrofuels. No efficiency for producing n- octane as an electrofuel was found and the efficiency was instead based on the average efficiency of other electrofuel production pathways. During the calculations regarding the potential fuel output for electrofuel, HTL with forest residues and HTL with food waste, the fuel energy density was assumed to be equal to that of A-1 jet fuel as no specific data was found. To reduce the competition from already existing forest industries the potential fuel that biomass from the forest could supply was based on forest residues currently not greatly used instead of doing a full scale analysis of the forest industries and their future needs, therefore, the actual amount of fuel that the Swedish forest can provide is probably lower. To address some of the data that was lacking in the literature study of this report we suggest for future work, that a well-to-wake life-cycle analysis of n-octane produced as an electrofuel is performed to get improved estimates of fuel costs, efficiency and energy use. We also recommend a full-scale analysis of the forest industries future needs in Sweden as that would allow for more precise calculations regarding the potential fuel output of HEFA with forest residues. An analysis of the amount of carbon that can be captured from zero GHG emission electricity sources would increase the precision of the potential fuel output for electrofuel. Another angle to the environmental perspective that was not addressed in this study but is of great interest is the land use change as biomass production increases and the resulting impacts on the regional and global environment. This thesis has had a technical focus but to get an even better understanding of the current and future state of SAF implantation in Sweden, we recommend that there be a similar depth in different stakeholders and polices about their involvement in SAF implantation.

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We recommend an implementation of HTL using forest residues as a feedstock to replace fossil- based jet fuel with regards to the perspectives given by the scope of the report. This is mainly due to its low price and very high potential fuel output.

7 Appendix

7.1 Calculations for PFO

7.2 Points available in each parameter

7.3 Grading

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