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The effect of the micro-porous layer (MPL) in polymer electrolyte fuel cells (PEFCs) was studied by a combination of in situ visualization of the liquid water distribution and advanced electrochemical analysis using helox and O2 pulses. Four cells with and without MPLs on the anode and cathode side were tested. Visualization studies showed that the significant changes in performance observed when using an MPL on the cathode side cannot be related to a reduction of the water content in the cathode side diffusion layer (GDL). The helox/O2 pulse analysis indicated that two different mechanisms are responsible for the performance loss without an MPL.
Shading indicates the ‘best’ vehicle architecture with the darkest shading and the ‘worst’ architecture with the lightest shading for each criterion. Please note that this appendix provides representative results that can be used to compare engine and hybridisation technologies; the MCDA algorithm may select vehicles that are not necessarily the best in this table because it has access to the full design set.
The analyses presented in this book have resulted in several overarching conclusions, which may be briefly summarised as follows:
Increasing transportation energy security and reducing the environmental impacts of personal vehicles are important high-level goals.
To achieve these goals, there is no single solution or ‘silver bullet’ pathway.
Hydrogen will only represent an attractive transportation fuel to meet stringent CO2 reduction targets if it is produced from primary energy resources with zero or low CO2 emissions in the future energy system.
The paradigm shift that is needed to make the transition from the current, problematic global transportation system will be led by the example of visionary communities, groups, and countries, using innovations that will necessarily be created by the developed world.
Both short- and long-term policy measures are needed to support the development of future mobility technology, in order to internalise costs and provide a pathway to clean transportation.
In addition, the following themes are central to the role that hydrogen can play as a transportation fuel and have been explored throughout this book:
The life cycle impacts of the full hydrogen fuel cycle were compared with conventional fuels.
Changes in the hydrogen emissions due to transport were analysed, along with their effects on atmospheric chemistry.
The ‘optimum’ design of a vehicle for any single buyer depends strongly on both the desired mix of performance and utility and on the available fuels. A multi-criteria methodology for an individualised assessment of vehicle design options has been developed.
Introducing hydrogen will require profound changes in the transportation system. The dynamics of the way innovations diffuse into transportation markets was therefore studied, considering barriers, opportunities, and feedbacks.
Energy–economic models have been used to generate scenarios maximising inter-generational welfare. Resource scarcity and climate protection goals were identified as important drivers promoting changes in the transportation system.
Deep cuts in global GHG emissions are required to keep the average increase in global temperature below 2°C (IPPC, 2007c; Sokolov et al., 2009). A strong need for action concerning road traffic as a main originator of GHG emissions through their almost exclusive use of fossil energy carriers is acknowledged (Ribeiro et al., 2007), as discussed in previous chapters. In this chapter, we analyse which technological drivetrain pathways and deployment strategies are required to meet the long-term, global challenge posed by climate change. We implicitly assume that the required technology change must be governed and managed by concerted decision making of entrepreneurial and political leaders. Many policy studies address the mid-term impact of incremental, energy-efficiency improvements of conventional ICE, or hybrid technologies and biofuels (Bandivadekar et al., 2008b; Hankey and Marshall, 2009; Meyer and Wessely, 2009). However, a longer term view on fleet dynamics addressing not-yet-regulated policy measures is missing from the literature. Also, most of the fleet models do not discuss the impact of preference changes on the diffusion process of alternative drivetrain technologies and the effectiveness of corresponding policy measures (Greene et al., 2007; McCollum and Yang, 2009; Thomas, 2009).
In this chapter, we present simulation experiments that illustrate the impact of vehicle technology purchase preferences. The system dynamics fleet model developed and used, therefore, offers a long-term view for the EU, addressing the question of what kind of drivetrain technologies have the potential to meet the scientifically indicated, GHG emission targets. Illustrative diffusion scenarios and the CO2 impact of competing drivetrain technologies, including advanced ICE, hybrid technologies, and vehicles fuelled with gaseous fuel (i.e. LPG, CNG) as well as near zero-emission vehicles (i.e. renewable HFCV) are presented.
The transition to a sustainable energy supply is one of the major challenges that humans will face during the twenty-first century. This transition is inevitable, but there are many scenarios discussed for how and when this will happen. Humans have relied on renewable energy for most of history, and will do so again, as affordable supplies of fossil fuels decline in the coming decades (or centuries). However, there is wide agreement that the world should not give up the benefits of modern technology. The transition to a ‘green’ energy supply has already begun, and technologies for collecting and converting energy from the environment, new means of energy storage, and increased energy efficiency have progressed greatly. That is why there is legitimate hope that the coming change will be possible without a major reduction in the quality of life.
Individual mobility and long-distance travel have become vital elements of human existence. This mobility and the freedom it enables are taken for granted by most, and even considered a fundamental right. Most of this mobility is provided by the more than 900 million motor vehicles that now populate roads around the globe. An enormous number – and expected to grow to more than 1.1 billion in less than a decade. If all the motor vehicles on the globe were put bumper to bumper, the resulting giant traffic jam would be 4.5 million kilometres long, or wrap around the globe more than 100 times.
The development of the vehicle fleet in the selected countries was estimated regarding their demographic and economic perspectives. Recent predictions by Alho et al. (2006) are that the population size in the European Economic Area (EEA) including Switzerland will increase slightly from the current level of 392 million to 427 million inhabitants by 2050. This median scenario by Alho et al. (2006) was chosen as the basis for the estimation of the fleet sizes for the first half of the twenty-first century, followed by a slight decrease from 2050 to 2100. This has been complemented by data from the Council of Europe (2005) on the population increase between 1995 and 2004, where Germany, Italy, Great Britain, Sweden, and Poland show a 0% increase, France and Switzerland between 2% and 5%, and Spain between 6% and 10%.
The economic aspect of the development is represented by the GDP, which shows the increase in value of all final goods and services produced within a nation in a given year (not taking into account purchasing power parity but taking into account inflation). It is used as a measure of economic development. The values are taken from the World Factbook (CIA, 2008). The computed fleet sizes are a result of data-deduced growth curves and take the values shown in Figure E.1.
When the project that forms the basis for this book was initiated in 2006, hydrogen was enjoying immense popularity as a possible alternative to fossil fuels as an energy storage vector. Record-breaking attendance at fuel cell exhibitions was common, and the news media was full of the ambitious market introduction plans of fuel cell company representatives and the grand hopes of politicians. It is now 2011, and the euphoria surrounding hydrogen has shifted to batteries and all-electric vehicles; the ‘electron economy’ is being advertised in much the same way. Hype surrounding transportation technology is a common phenomenon, and history provides us with many examples of announcements of ‘major breakthroughs’. Some, like fuel injection, caught on; others, like the ‘Nucleon’ nuclear powertrain, did not. Whether hype hampers or helps society to find and to implement the best solutions for our pressing social and environmental problems is debatable. What is certain is that a thorough analysis of technological alternatives, and perseverance in execution once the best solution (or set of solutions) has been identified, should never be superseded by action plans driven by media attention.
The Alliance for Global Sustainability is the framework that facilitated collaboration between John Heywood’s group at the Massachusetts Institute of Technology and Alexander Wokaun’s team at the Paul Scherrer Institute in investigating vehicle technology alternatives ‘Before the Transition to Hydrogen’. With generous financial support from the Swiss Competence Center for Energy and Mobility (CCEM), these two working groups met biannually with sponsors and partners from industry and professional associations, to share ideas and to engage in exciting multidisciplinary research. The results of the Swiss team’s research are contained in this book. Even though, occasionally, the opinions of the partners from opposite sides of the Atlantic regarding the potential of the various transportation energy technologies investigated did not converge, the collaboration was highly successful because of the high value that both research teams placed on objective and unbiased analysis. In particular, the MIT group’s strength in combustion engine technology and policy research proved to be highly complementary to the PSI group’s technical know-how regarding fuel cells, global energy system modelling, and scenario analysis.
This book is a comprehensive and objective guide to understanding hydrogen as a transportation fuel. The effects that pursuing different vehicle technology development paths will have on the economy, the environment, public safety and human health are presented with implications for policy makers, industrial stakeholders and researchers alike. Using hydrogen as a fuel offers a possible solution to satisfying global mobility needs, including sustainability of supply and the potential reduction of greenhouse gas emissions. This book focuses on research issues that are at the intersection of hydrogen and transportation, since the study of vehicles and energy-carriers is inseparable. It concentrates on light duty vehicles (cars and light trucks), set in the context of other competing technologies, the larger energy sector and the overall economy. The book is invaluable for researchers and policy makers in transportation policy, energy economics, systems dynamics, vehicle powertrain modeling and simulation, environmental science and environmental engineering.