A Hydrogen Advocate Whose Time Has Come Peter Hoffmann started what is now the Hydrogen and Fuel Cell Letter in 1986 and is the author of two books on this potential energy carrier for automobiles. "Tomorrow's Energy: Hydrogen, Fuel Cells and the Prospects for a Cleaner Planet" was published in 2001, but a revised and expanded edition is scheduled to be available from M.I.T. Press in March. Advocating for hydrogen cars has been, at times, a lonely profession, because fuel-cell vehicles have long been just around the next bend. But several major automakers have committed in recent months to hydrogen car production by 2015. The cars and the hydrogen are likely to be expensive in the early years, but Mr. Hoffmann, a native of Germany, and other advocates expect those costs to decrease as production ramps up and technology matures. Fuel-cell cars are regarded as zero emission because they don't emit anything but water vapor from their tailpipes.They use the same basic drivetrains as electric vehicles, but in lieu of batteries they substitute a fuel-cell chemical factory that produces electricity by combining hydrogen and oxygen. Q. The California Air Resources Board just approved new regulations designed to put 500,000 zero-emission cars on the road by 2025. More than 160,000 of those vehicles would be hydrogen fuel-cell cars in one scenario. The regulations also require oil companies to build hydrogen refueling stations. Is this a big leap forward? A. I certainly hope so - it's definitely a step along the way. The Japanese and Europeans (and especially the Germans) are setting up similar schemes supporting collaborations between carmakers and fuel providers to set up hydrogen stations. In those cases, there's a lot of government money involved. Q. California would seem to be the epicenter of fuel-cell deployment in the United States, but even in Los Angeles today there are only a few public stations. Will there be a network in place by the time automakers roll out the first commercial fuel-cell cars in 2015? A. The California Fuel Cell Partnership is working hard to get more stations going. And the new CARB rules will also help. Q. The Clean Fuels Outlet provision of CARB's rules will require oil companies to install hydrogen pumps at gas stations. The Western States Petroleum Association trade group has announced strong opposition and will possibly sue over it. A. The oil companies are being more cooperative with hydrogen fueling in Europe, so their actions may depend on how the political winds are blowing. If the oil companies are not in the forefront, there are other companies in the wings that are very active and want to provide hydrogen infrastructure. These include major industrial gas companies like Linde, Air Products and Air Liquide. Mercedes, for instance, is working with Linde to build 20 stations in Germany. Q. What's been your experience behind the wheel of fuel-cell cars? A. I've driven quite a few, from G.M., Mercedes, Honda, Toyota, Mazda and Ford. I remember early Ford cars in the 1990s that lacked noise insulation and sounded like they had angry bees under their hoods. The cars have evolved considerably since then and are as fun to drive as anything else on the road. Automakers say they're committed to fuel-cell production by 2015, and now they need to ensure that at least the beginnings of a hydrogen station network is built. Q. Will the cost of hydrogen come down? A. It will be competitive with gasoline eventually. At Stuttgart Airport in Germany, a station was selling it recently for $12 a kilogram. Since a kilo of hydrogen is the energy equivalent of a gallon of gas, and a fuel cell is twice as efficient as an internal-combustion engine, you could translate that into approximately $6 a gallon. That's roughly what gasoline costs in Europe. Of course, hydrogen is probably subsidized at that price, but it indicates the potential for price reductions. The price will come down as more fuel providers get into the field, as production methods such as electrolysis and other forms evolve, and as storage and compression technology is made more efficient. Q. Will consumers accept fuel-cell cars? A. The people who have driven them are happy, but of course they tend to be hydrogen supporters.They say the cars are smooth and convenient to use, accelerate well and refuel very quickly, which is a big selling point. The one issue that disappoints people about battery electrics is range, and that's not an issue for fuel-cell cars, which often travel 300 miles on a tank of hydrogen. Q. What about the safety issue? The Hindenburg disaster still looms large for many. A. From what I understand, these cars are as safe as they can be - as safe as gasoline cars. Even if hydrogen tanks leak, the gas just evaporates into the air, and there are extensive safety and warning devices built into the cars. In an accident, the hydrogen supply is cut off and valves automatically vent it in case of a pressure build-up. The concern will always be there, let's face it, because hydrogen is very flammable. But the automakers tell me it won't be an issue. I remember seeing a BMW film in the 1980s in which they dropped hydrogen tanks off a gantry, cooked them over a fire and tried to pierce them with a device. Nothing happened. Q. Any projections of how many fuel-cell cars might be on American roads by 2025? A. It's hard to say, and I'm not a futurist or a prophet. I'll cite the CARB estimate of 500,000 zero-emission cars by 2025, with maybe a third being fuel-cell vehicles.