REVIEWED BYDAVID HART

The hydrogen economy--a world where hydrogen has become the primary energy currency--is attracting increasing interest from scientists, policymakers, and industry alike. The idea was first touched on in science fiction more than a century ago by writers such as Jules Verne. Increasing technological development is now enticing major corporations to explore the possibilities it offers. Simple though the concept is, however, many misconceptions, half-truths, and misleading statistics obscure its real potential and pitfalls. In "Tomorrow's Energy: Hydrogen, Fuel Cells, and the Prospects for a Cleaner Planet," Peter Hoffmann discusses hydrogen and fuel cells--a key technology that is driving forward a hydrogen economy--with clarity and a light touch.

Hoffmann is well placed to do this. He has reported on hydrogen energy since the 1970s, and currently edits the monthly Hydrogen & Fuel Cell Letter, a key source of information in the industry. His 1981 book, "Hydrogen: The Forever Fuel," set the foundation for his new book.

TOMORROW'S ENERGY: HYDROGEN, FUEL CELLS, AND THE PROSPECTS FOR A CLEANER PLANET, by Peter Hoffmann, MIT Press, 2001, 289 pages, $32.95 (ISBN 0-262-08295-0)

Interest in hydrogen energy has been fitful over the 200 or so years since Antoine Lavoisier first named this element. Hoffmann primarily chronicles the peaks in interest, such as the pioneering work of German engineer Rudolf Erren, who converted hundreds of vehicles of many types so they could run on hydrogen or hydrogen-rich mixtures of fuel in the 1930s. Other high points discussed are the first vehicles powered by fuel cells developed by organizations such as Allis-Chalmers, and the "Home of Tomorrow," in which the Institute of Gas Technology expounded on the benefits of using hydrogen-rich "reformed natural gas" for heating, cooking, and lighting, both in the 1960s. More recent developments are covered in detail, and the book closes with a brief outlook for the future.

That future is unclear. Organizations like the International Institute for Applied Systems Analysis (IIASA), a nongovernmental research organization in Austria, argue that major energy transitions take 50 to 100 years. The institute's own research certainly bears this out. IIASA also points out the recent trend toward fuels that are richer in hydrogen (relative to carbon) in the global energy supply. We may now be sitting at the cusp of an energy revolution potentially as significant as previous transitions from coal to oil or from oil to natural gas.

It's that underlying possibility that is exciting and deserves further consideration. The fuel cell may play the role of the internal combustion engine or the gas turbine as the technology that enables this changes. Techniques for storing, transporting, and handling hydrogen--a comparatively awkward substance--are evolving rapidly. These new techniques should provide the link between production and use of hydrogen in an energy chain, whether to power vehicles or as a source of power for stationary uses. The crucial and fascinating questions yet to be understood--or fully explored--concern the timescale over which the transition can take place in different countries, the leading applications, and the triggers that will enable particular areas to move toward a cleaner fuel.

"Tomorrow's Energy" presents a number of useful starting points for consideration of these topics. For example, it presents the work of individual champions of the hydrogen economy, such as Michael Otto of Otto-Versand, a German mail-order company, who is a driving force behind a fleet of demonstration hydrogen delivery vans in Hamburg. Geoff Ballard, instrumental in the development of the proton-exchange membrane (PEM) fuel cell and, some might say, of the entire fuel-cell industry, is another whose work has provided a solid foundation on which to move to hydrogen.

CLEAN MACHINES Low-emission buses.

Yet different energy and automotive companies remain divided in their approach. Governments, too, are divided. Thus, there appear to be fruitful opportunities for research and for development of many different solutions. Some advocates want to move rapidly to hydrogen derived from renewable resources--an expensive but clean and ultimately sustainable option. Others expect the use of fossil fuels to produce hydrogen to be an intermediate step, and some see hydrogen generated from nuclear electricity as the final end point.

The different choices for hydrogen generation presented in "Tomorrow's Energy" make clear the complexity involved in comparing these options. Processing of a variety of fossil fuels, biological systems using algae, and solar chimneys are among the myriad choices. Perhaps wisely, Hoffmann elects not to enter the debate on exactly which system offers the best environmental characteristics, a detailed and convoluted ongoing discussion among a variety of industry and academic experts. The majority of analyses conducted have been on fuels for transport, and, as Hoffmann points out, "At present there is no clear preference as to what the fuel should be for the first generation of fuel-cell cars."

Providing hydrogen to private cars will entail costly initial investment by fuel providers. One alternative--producing hydrogen on board the vehicle from gasoline or methanol--would make the vehicles themselves more costly, reduce their responsiveness, and leave them with poorer environmental credentials. On the other hand, a vehicle powered by a direct hydrogen fuel cell would have no harmful emissions. In general, analysts agree that producing hydrogen away from the vehicle--even from natural gas, though not coal--offers a better environmental route than on-board fuel processing.

The endgame is clear, but the transition is messy. Some fear, for example, that the use of on-board processors--especially of gasoline--could significantly hinder the development of a hydrogen economy. The PEM fuel cell, which is the one used in vehicles, operates best on comparatively clean hydrogen. Enabling that hydrogen to be produced on board by an environmentally inferior system, the argument goes, is likely only to prolong the status quo of gasoline use. For issues like this one, clear fiscal and regulatory policies are essential, yet the position of most governments is far from clear.

Hoffmann discusses many of the leading research programs and their impacts. The Japanese World Energy Network (WE-NET) project is taking an admirable long-term view, while the Canadian and German programs have high rates of involvement across different industries. The U.S. program, funded primarily by the Department of Energy, is probably the broadest. It's producing large amounts of valuable information across a range of subject areas. Hoffmann leaves the impacts of government policies, other than the critical drive provided by California's mandate for a zero-emission vehicle, for another time.

"At present there is no clear preference as to what the fuel should be for the first generation of fuel-cell cars."

In fact, the impacts of policy are largely unclear. Governments, both national and local, only very recently have begun
to consider specific policies for hydrogen, though their earlier decisions on vehicle emissions, air quality, and climate change have all had an influence on hydrogen development. However, apart from supporting specific strategic technology research, it is often better for governments to set targets and allow markets to find solutions, rather than mandating the use of particular technologies. Different policies in different fields--such as transport, security of the fuel supply, local air pollution, and climate change--can have conflicting or reinforcing effects. Tightening regulation on emissions certainly reinforces some of the advantages of hydrogen, and many of these other policy drivers may have a similar effect.

One of the weaknesses of hydrogen, as Hoffmann rightly points out, is also an opportunity: It's not a source of energy, per se, but a carrier of it. Hydrogen itself must be produced from a primary resource. This gives it versatility. Concerns about the security of energy supplies can be addressed by producing hydrogen from a wide range of different resources. Similarly, a hydrogen-based fuel economy would allow countries with significant renewable energy resources but limited fossil ones to compete more equitably in the world economy. Even international trade policy may act as a driver--or barrier--for hydrogen.

"Tomorrow's Energy" contains enough detailed description of the developments in hydrogen energy to be a useful basic reference. It is thoroughly readable and engaging throughout. Though its arguments are not expounded with scientific rigor, this is appropriate for a book aimed at a general readership, and the book provides a range of sources for those who wish to pursue further the many questions it raises.

My only minor disappointment is with the book's final chapter. Here, Hoffmann describes the future energy systems that have been investigated by IIASA and the World Energy Council. The work of these organizations provides a detailed and valuable study, but I would like to have seen it supplemented with more discussion and opinion from other sources, including the energy and automotive industries and more radical thinkers including energy guru Amory Lovins, founder of the Rocky Mountain Institute. Those additions would have added spice and a greater sense of vision to the book. This is, however, a minor flaw in an otherwise excellent book, which will inform people both within and outside the emerging hydrogen industry. It deserves a wide audience.

David Hart heads a research team at Imperial College, London, studying techno-economic, policy, and environmental implications of fuel- cell and hydrogen energy systems. He is also a director of E4tech, a consulting firm specializing in strategic energy and environment issues.

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