Safety Considerations on Liquid Hydrogen Karl Verfondern Helmholtz-Gemeinschaft der 5/JULICH Mitglied FORSCHUNGSZENTRUM TABLE OF CONTENTS 1. INTRODUCTION....................................................................................................................................1 2. PROPERTIES OF LIQUID HYDROGEN..........................................................................................3 2.1. Physical and Chemical Characteristics..............................................................................................3 2.1.1. Physical Properties ......................................................................................................................3 2.1.2. Chemical Properties ....................................................................................................................7 2.2. Influence of Cryogenic Hydrogen on Materials..............................................................................9 2.3. Physiological Problems in Connection with Liquid Hydrogen ....................................................10 3. PRODUCTION OF LIQUID HYDROGEN AND SLUSH HYDROGEN................................... 13 3.1. Liquid Hydrogen Production Methods ............................................................................................ 13 3.1.1. Energy Requirement .................................................................................................................. 13 3.1.2. Linde Hampson Process ............................................................................................................15 3.1.3. Claude Process .......................................................................................................................... 16 3.1.4. Magnetic Refrigeration Process ...............................................................................................20 3.2. Safety Issues......................................................................................................................................21 3.3. Liquefaction Efficiency ....................................................................................................................22 3.4. Present Hydrogen Liquefaction Capacity in the World ...............................................................22 3.5. Slush Hydrogen Production Methods ..............................................................................................23 4. STORAGE OF LIQUID HYDROGEN..............................................................................................25 4.1. Principal Tank Design ...................................................................................................................... 25 4.2. LH2 Tanks for Mobile Applications ................................................................................................28 4.2.1. Passenger Car Tank Design ...................................................................................................... 28 4.2.2. Safety Tests with LH2 Vehicle Tanks...................................................................................... 30 4.3. Stationary LH2 Tanks.......................................................................................................................33 5. TRANSPORTATION OF LIQUID HYDROGEN...........................................................................37 5.1. Road Transportation of LH2............................................................................................................ 37 5.2. Maritime Transportation of LH2...................................................................................................... 39 5.3. Rail Transportation of LH2...............................................................................................................43 iii Schriften des Forschungszentrums Julich Reihe Energie & Umwelt / Energy & Environment Band / Volume 10 Forschungszentrum Julich GmbH Institut fur Energieforschung (IEF) Sicherheitsforschung und Reaktortechnik (IEF-6) Safety Considerations on Liquid Hydrogen Karl Verfcndern Schriften des Forschungszentrums Julich Reihe Energie & Umwelt / Energy & Environment Band / Volume 10 ISSN 1866-1793 ISBN 978-3-89336-530-2 Bibliographic information published by the Deutsche Nationalbibliothek. The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available in the Internet at http://dnb.d-nb.de . Publisher Forschungszentrum Julich GmbH and Distributor: Zentralbibliothek, Verlag D-52425 Julich phone:+49 2461 61-5368 ■ fax:+49 2461 61-6103 e-mail: [email protected] Internet: http://www.fz-juelich.de/zb Cover Design: Grafische Medien, Forschungszentrum Julich GmbH Printer: Grafische Medien, Forschungszentrum Julich GmbH Copyright: Forschungszentrum Julich 2008 Schriften des Forschungszentrums Julich Reihe Energie & Umwelt / Energy & Environment Band / Volume 10 ISSN 1866-1793 ISBN 978-3-89336-530-2 The complete volume is freely available on the Internet on the Julicher Open Access Server (JUWEL) at http://www.fz-juelich.de/zb/juwel Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher. Abstract The interest in hydrogen as a clean fuel and energy carrier of the future has grown in many countries and initiated comprehensive research, development, and demonstration activities with the main objective of the transition from a fossil towards a CO2 emission lean energy structure as the ultimate goal. Reasons for these worldwide incentives towards a change of the energy structure are the obvious indications for a climate change from man-made greenhouse gas emissions, the steadily increasing world energy consumption connected with the finite nature of fossil resources, but also the need of reducing national dependencies on energy imports. Hydrogen represents an energy carrier with high energy content and a clean, environmentally friendly source of energy to the end-user. The volume-related energy content of gaseous hydrogen, however, is comparatively small. For various applications of hydrogen where volume is an essential issue, it is necessary, e.g., to liquefy the hydrogen for the sake of volume reduction. But there are also other situations where the liquid state represents a reasonable and economic solution for storage and distribution of large amounts of hydrogen depending on the end-user’s requirements. Furthermore liquid hydrogen has the advantage of extreme cleanliness making it, apart from its cooling ability, appropriate in many industrial applications. Major drawback is the enormous energy input required to liquefy the hydrogen gas, which has a significant impact on the economy of handling LH2. The experimental and theoretical investigation of the characteristics of liquid hydrogen, its favorable and unfavorable properties, as well as the lessons learnt from accidents have led to a set of codes, standards, regulations, and guidelines, which resulted in a high level of safety achieved today. This applies to both LH2 production and the methods of mobile or stationary LH2 storage and transportation/distribution, and its application in both science and industries. The hazards associated with the presence and operation of LH2 containing systems are subject of safety and risk assessments. Essential part of such accident sequence analyses is the simulation of the physical phenomena, which occur in connection with the inadvertent release of LH2 into the environment by computation models. The behavior of cryogenic pool propagation and vaporization on either a liquid or a solid ground is principally well understood. Furthermore state-of-the-art computer models have been developed and validated against respective experimental data. There are, however, still open questions which require further efforts to extent the still poor experimental data basis. These efforts should include the examination of the pool propagation from large spills of LH2, the vaporization on different grounds, and pool fire, but also the atmospheric dispersion behavior of cold vapor clouds evolving from the vaporization of the cryogenic liquid. i Kurzfassung Weltweit ist das Interesse an Wasserstoff als einem umweltfreundlichen Brennstoff und moglichen Energietrager der Zukunft gestiegen und hat umfassende Forschungs- und Entwicklungsarbeiten ausgelost. Ziel ist es dabei, den Ubergang von einer fossil-gesteuerten hin zu einer weitgehend CO2-emissionsfreien Energiestruktur zu fordern. Ausloser fur diese Anstrengungen sind die offensichtlichen Anzeichen eines Klimawandels infolge erhohten AusstoBes von Treibhausgasen, der weltweit stetig wachsende Verbrauch an Energie verbunden mit den allmahlich zu Neige gehenden Vorraten an fossilen Energievorraten, aber ebenso die Notwendigkeit vieler Staaten, ihre nationale Abhangigkeit von Energieimporten zu mildern. Wasserstoff ist ein attraktiver Energietrager mit hohem masse-bezogenen Energiegehalt und stellt eine fur den Endverbraucher umweltvertragliche Energiequelle dar. Der volumen- bezogene Energieinhalt gasformigen Wasserstoffs jedoch ist vergleichsweise gering. Viele Anwendungen, in denen das Volumen eine wichtige Rolle spielt, erfordern daher eine Verflussigung des Wasserstoffgases aus Grunden der Platzersparnis. Ferner ist Speicherung und Transport von Wasserstoff in flussiger Form