Toward a Hydrogen Economy

Policymakers around the world are calling for major energy-consuming nations to move from reliance on fossil fuels to an energy economy mediated by hydrogen. A special section in the 13 August issue of Science—including a "Review," two "Viewpoints," an editorial and a Science news package—assesses the prospects for such a transition and describes technological developments necessary for making it a reality.

Short-Term Solution to Climate Problem
Humans already have the technological know-how to decrease carbon dioxide emissions to a level this "Review" article considers low enough to prevent most damaging climate change over the next 50 years. The authors identify 15 options for achieving meaningful greenhouse gas reductions that are available now. These include improving the efficiency in cars, coal plants and buildings as well as increasing generation of wind, nuclear and renewable hydrogen power. None of the approaches outlined by Stephen Pacala and Robert Socolow is capable of adequately limiting emissions alone. Implemented together, however, they could make up a portfolio that can keep atmospheric carbon dioxide concentrations below 500 parts-per-million, which is twice the preindustrial concentration of atmospheric carbon dioxide. The current atmospheric carbon dioxide concentration is approximately 375 parts-per-million. The authors note that basic research is vital to develop the radical new technologies, such as fusion and artificial photosynthesis, which may be needed in the second half of this century and beyond.

Seeking Sustainability
A sustainable hydrogen economy is possible, but only with a sustained, focused effort, according to a "Viewpoint" article. Since at least the 1930s, visions of a hydrogen economy have involved using sustainably-produced hydrogen to store electrical energy, reduce greenhouse gas and other emissions, and provide a transportation fuel. To meet this goal, the electricity needed to produce vast amounts of hydrogen must come from sources such as the sun and the wind. Today, hydrogen is primarily produced from natural gas, a process which is not sustainable. John Turner writes that identifying and building a sustainable energy system are perhaps two of the most critical issues that contemporary societies must address. Turner describes some of the technical and economic issues related to hydrogen production today and considers some of what will be required to build a hydrogen economy in the future.

Hybrid Cars vs. Fuel Cell Cars
Today's gasoline/electric hybrid cars already offer many of the environmental and energy independence benefits of the hydrogen fuel cell cars of the future, according to a "Viewpoint" article. A hybrid vehicle available today may limit atmospheric carbon dioxide emissions and aid in energy independence nearly as well as hydrogen fuel cell cars of the future — at least until the hydrogen is produced in a sustainable fashion. Hybrid cars include an electric motor and parallel drive train, which eliminates idling loss and captures some energy of braking. The authors note that in Europe, where fuel prices are much higher than in the United States, the advantage of hybrids over conventional cars with internal combustion engines is significantly greater. Governments should consider expanding support for research and development on hybrid technologies and extending hybrid vehicle tax credits, the authors write.

Special News Package
In one of four News stories in the special section, Robert Service examines arguments for developing a broader-based, nearer-term energy policy, given the outstanding questions about how a hydrogen-based economy can work. In another story, Service describes the growing interest in capturing and storing carbon dioxide, which will be necessary as we learn to wean ourselves of fossil fuels. Adrian Cho reports on the development of internal combustion engines that run on hydrogen. And, Gretchen Vogel, with reporting by Dan Clery, looks at Iceland’s plan for implementing a hydrogen-based economy by 2050.

— Daniel B. Kane

13 August 2004