Converting all the automobiles in the United States to hydrogen fuel-cell technology would prevent millions of cases of respiratory illness and tens of thousands of hospitalizations annually, according to Stanford researchers Mark Z. Jacobson, Whitney Goldsborough Colella, and David M. Golden. Their article, published in the 24 June issue of Science, described how a full-scale conversion would improve air quality, health, and climate, particularly if hydrogen production were powered by wind.

"Switching from a fossil-fuel economy to a hydrogen economy would be subject to technological hurdles, the difficulty of creating a new energy infrastructure, and considerable conversion costs but could provide health, environmental, climate and economic benefits and reduce the reliance on diminishing oil supplies," the authors wrote.

Using the proposed technology, hydrogen would be pumped into fuel cells--much the way that gas is pumped into tanks--where it would react with oxygen to produce water and energy. The environmental impact of getting the initial hydrogen is dependent on how the electrolytic process is powered: If it is by steam reforming of natural gas or by coal gasification, carbon dioxide and other pollutant byproducts can be produced. However, if the process is powered by wind, no such pollution is created. Jacobson envisions wind turbines generating electricity on wind farms that are linked in a network to ensure energy production even when parts of the grid have windless days. The electricity would travel through transmission lines to a filling station. There, it would enter an electrolyzer, splitting water molecules into oxygen, which would be released into the air, and hydrogen, which would get compressed and stored.

Some are concerned about hydrogen's explosiveness, but Jacobson claims that because hydrogen is 14 times lighter than air, this danger is minimized. He cites an example of two cars--one conventional, one hydrogen-powered--that were hit from behind. The car powered by an internal combustion engine became engulfed in flames when its gas tank was punctured. But when the hydrogen car's fuel cell was punctured, the flames shot straight up into the air and kept the rest of the car from catching on fire. Hydrogen's volatility, however, underscores the need to develop tight seals to prevent leakage from storage tanks, filling stations, and the fuel cells themselves.

--Stanford University press release, 24 June. (M.P.)

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