Technology Status of Hydrogen Road Vehicles

1.0 Introduction
This report was commissioned under the Hydrogen Implementing Agreement of the International Energy
Agency (IEA), and examines the state of the art in the evolving field of hydrogen-fueled vehicles for road
transport. The first phase surveys and analyzes developments since 1989, when a comprehensive review was
last published (DeLuchi 1989). The report emphasizes the following:
! Problems, especially backfiring, with internal combustion engines (ICEs)
! Operational safety
! Hydrogen handling and on-board storage
! Ongoing demonstration projects.
Hydrogen vehicles are receiving much attention, especially at the research and development level. However,
there has been a steady move during the past 5 years toward integral demonstrations of operable vehicles
intended for public roads. Because they emit few, or no greenhouse gases, hydrogen vehicles are beginning
to be taken seriously as a promising solution to the problems of urban air quality.
Most information sources for this report are published documents. Some were supplied by IEA and European
Community officials, but most were accessed from the document retrieval systems in common scientific use.
Several hundred documents were scanned for interest; about 150 were studied for relevance to this report.
Most had some bearing on the way the report is presented, but only the 50 actually quoted or referred to in
the text are listed in the References section. Much work of direct relevance is undoubtedly missing, either
because it is too recent or too proprietary. In a fast-moving field of some industrial importance, the best
results are kept under wraps until the time is ripe for exploitation. And some relevant published work may
have been overlooked.
The starting point for this study is the comprehensive work of DeLuchi (1989). It is rich with the input of 165
documents consulted, and should be read in conjunction with this report. In particular it makes a life-cycle
cost comparison among the various technologies, and concluded that even 6 years ago the economics of some
hydrogen vehicles was already competitive.
Since the time the first draft of this report was prepared (mid-1996), the 11th World Hydrogen Energy
Conference took place in Stuttgart, Germany. This biennial conference can be regarded as a valid updating
of the state of the art; therefore, the 1996 results are included in this current version. Those of interest to
hydrogen vehicles are discussed throughout this report, with the most detail included in Appendix 4.
A summary of DeLuchi 1989 is also included. For convenience, this is also presented in Appendix 4. As a
consequence of this updating, we also became aware of a valuable report, not yet available in the public
literature, concerning a comprehensive safety investigation on hydrogen (EQHHPP Nov. 1993). Awaiting its
publication, we can only include a brief summary in Appendix 1 on safety questions.
2.0 Hydrogen Production and Distribution to Urban Users
2.1 Hydrogen Production and Bulk Transport
Hydrogen as a fuel (or more correctly as an energy vector) for any application is inseparable from its basic
rationale: recourse to clean and renewable energy (clearen). The interdependence of hydrogen and clearen
is so strong that one can hardly become widespread without the other.
Clearens are all sun-derived on a short cycle, and include photovoltaics, wind, hydropower, and energy crops
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