University of Birmingham HYDROGEN AS AN ENERGY CARRIER FOR RAILWAY TRACTION by Andreas Hoffrichter A thesis submitted to the University of Birmingham for the degree of DOCTOR OF PHILOSOPHY The Birmingham Centre for Railway Research and Education Electronic, Electrical and Computer Engineering College of Engineering and Physical Sciences The University of Birmingham April 2013 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. © 2013 by Andreas Hoffrichter All rights reserved ABSTRACT Our way-of-life depends on effective transportation: commuting to the work place, travel for business, and cargo shipments around the globe are natural to many of us. Railways are an integral part of the transportation system, enabling the effective and efficient movement of bulk cargo as well as of commuters or intercity travellers. At a global level, the energy required for railway traction is predominantly provided by diesel, followed by a 30 % share of electricity. Uncertainty about economical diesel supply, and environmental as well as public health concerns about exhaust gases, has promoted the exploration of alternatives. Electrification is a traditional method to evade fuel supply problems and prevent emissions at the point-of-use, but the high capital investment is often uneconomical or unaffordable for private rail companies. Therefore, traction that does not rely on wayside infrastructure for energy supply remains the only choice in many cases. Hydrogen as a secondary energy, like electricity, can be produced from various feedstocks, including fossil fuels, nuclear power, and renewables. Thus, a reduction or elimination of greenhouse gas emissions is possible. Fuel cells combine hydrogen with oxygen from the ambient air to create electricity and heat while producing pure water as exhaust. No harmful point-of-use emissions, apart from some heat, result and fuel cells are efficient energy conversion devices. Hydrogen is a gas at ambient temperatures and compression or other storage methods are required for utilisation as a fuel. Currently, the cost of the energy conversion systems as well as the more complex storage tanks compared to liquid fuels are drawbacks of hydrogen. The environmental performance and overall efficiency depend on the on-board energy conversion and the energy supply chain, in the case of railways: diesel or electricity. To evaluate the suitability of hydrogen, a well-to-wheel analysis for the aforementioned energies was conducted. The results, based on the lower heating value of fuels, show that hydrogen fuel cell traction with hydrogen produced from natural gas has similar efficiencies to electric traction in the UK and in the USA at approximately 25 %, while reducing carbon emissions by 19 % compared to diesel in 2008. Thus, hydrogen yields similar or better results than incumbent systems. A prototype locomotive, Hydrogen Pioneer, was designed, developed, and constructed to demonstrate, together with associated empirical performance tests, whether hydrogen is suitable for railway traction. A relatively high power-plant efficiency of up to 40 % during duty-cycles, and 43 % in the steady-state, was observed, while no technical problems with the hydrogen systems were encountered. The positive results led to comparative computer simulations for the route Birmingham Moor Street to Stratford-upon-Avon and return. A diesel-electric regional train, which served as a benchmark, a hydrogen-powered vehicle, and a hydrogen-hybrid version were modelled. All the required hydrogen equipment could be accommodated in the respective trains, if 700 bar tanks were employed, and the journey time as well as the range of both hydrogen trains were similar to the diesel version: 94 minutes and 16 hours, respectively. An energy reduction of 34 %, with the hydrogen vehicle, and 55 % with the hydrogen-hybrid train, is achieved compared to the benchmark diesel. Commercial viability and risks associated with hydrogen as a railway fuel were outside the scope of the work and, therefore, they were not investigated in detail. Overall, the research provides evidence that hydrogen-powered railway traction is technically possible, reduces energy consumption, has water as exhaust, decreases overall greenhouse gas emissions, and is not dependent on petroleum. TABLE OF CONTENTS List of Illustrations .........................................................................................................ix List of Figures............................................................................................................ix List of Tables .......................................................................................................... xiii Acknowledgments ..........................................................................................................xv List of Abbreviations .................................................................................................. xvii 1 Introduction ..............................................................................................................1 1.1 Early Land Transport Systems ..........................................................................1 1.2 Electric Traction................................................................................................2 1.3 Diesel Traction ..................................................................................................7 1.4 Situation Today ...............................................................................................17 1.5 Research Hypothesis .......................................................................................19 1.6 Thesis Scope ...................................................................................................21 1.6.1 Economic Considerations............................................................................. 21 1.6.2 Risk and Safety............................................................................................. 22 1.7 General Methodology .....................................................................................23 1.8 Document Structure ........................................................................................24 PART I: LITERATURE-BASED RESEARCH 2 Background .............................................................................................................29 2.1 Energy Consumption, Market Share, and Emissions......................................29 2.1.1 Energy Sources............................................................................................. 31 2.1.2 Emissions ..................................................................................................... 34 2.2 Hydrogen as a Transportation Fuel .................................................................37 2.2.1 Hydrogen Energy Conversion ...................................................................... 38 2.2.2 Hydrogen as a Fuel in the Automotive Sector.............................................. 42 2.2.3 Hydrogen-Powered Railway Traction Prototypes ........................................ 51 2.3 Summary .........................................................................................................58 Contents 3 Hydrogen Supply ....................................................................................................60 3.1 Hydrogen Production ......................................................................................60 3.1.1 Hydrogen Production from Fossil Fuel Feedstock ....................................... 63 3.1.2 Hydrogen Production from Renewable Feedstock ....................................... 67 3.2 Hydrogen Transportation and Distribution .....................................................70 3.2.1 Pipeline ......................................................................................................... 70 3.2.2 Other Transportation and Distribution Options............................................ 75 3.3 Hydrogen Storage ...........................................................................................79 3.3.1 Storage as a Compressed Gas....................................................................... 79 3.3.2 Storage as a Liquid ....................................................................................... 81 3.3.3 Cryo-Compressed Storage............................................................................ 83 3.3.4 Storage in Solids........................................................................................... 84 3.3.5 Comparison of On-Board Storage Technologies ......................................... 86 3.3.6 Large-Scale Storage in Caverns ................................................................... 87 3.4 Summary .........................................................................................................89 4 Well-to-Wheel Analysis ..........................................................................................92 4.1 Method and Boundaries