'Soap' may make clean fuel-cell cars feasible

Besides, corner gas stations don't sell hydrogen. So fuel-cell cars would need new or retrofitted hydrogen filling stations.

While hydrogen can be refined from water, no facilities have the capacity to fuel America's 200 million-plus vehicle fleet.

Other running prototype fuel- cell cars so far have used gaseous or liquid hydrogen, or an on-board chemical factory - a "reformer" - to produce hydrogen.

All these technologies have their limits:

• Hydrogen gas has to be stored in giant, cylindrical, pressurized tanks that take up the space of at least two seats and most of the cargo area in a typical minivan. That's much larger than other storage forms. In addition, gaseous hydrogen conjures mental images of the 1937 Hindenburg disaster in public perception. The Zeppelin airship burned and crashed on landing in New Jersey. Public perception has long blamed the volatile hydrogen lifting gas for the fire.

But more recent studies have cast doubt on hydrogen's role in the disaster. Film images of the fire indicate that it was the skin of the Hindenburg caught fire.

• Liquid hydrogen contains many more molecules in a smaller tank and so could give a hydrogen vehicle the range of a gas-powered car. But it evaporates into a gas at only a few degrees above absolute zero - minus 460 degrees Fahrenheit. So the smaller fuel tank needs rampart-thick insulation - more wasted space.

And "you use almost as much energy cooling the hydrogen as it produces" in the fuel cell, says Mr. Moore. So it's not at all clear that liquid hydrogen will ever be cost-effective.

• Reformers, which produce hydrogen from hydrogen-rich methane or common gasoline, would solve many distribution problems. You could fill up at your corner station. But the reformers produce pollution much like today's engines (though less of it), and so negate a key advantage of hydrogen. They take up almost as much room in the car as a gaseous hydrogen tank, produce infernal heat, and take up to 30 minutes to warm up.

DaimlerChrysler's Natrium minivan solves several problems: It stores hydrogen in a fifth the space of gaseous hydrogen; it needn't be under pressure in a large cylindrical tank; it doesn't require a large, hot, dirty reformer; and it is not flammable.

The spent fuel (soap) would be pumped back out of the gas tank at fill-up time to be recycled into more sodium borohydride.

The idea is not technically new, but advancing catalytic-converter technology has made the process space- and cost-efficient enough to fit under the floor of a slightly raised minivan.

The van uses a catalyst to convert sodium borohydride into borax, water, and hydrogen. A bladder in the fuel tank separates spent borax from the fuel. The fuel cell makes electricity to drive the van via an electric motor.

What's missing is the infrastructure to convert the spent borax solution back into sodium borohydride - and a pump to refuel the van and recycle the borax. Today the van runs on industrial-grade sodium borohydride and the nontoxic borax waste is simply dumped.

"We're showing this [prototype] to the public now to try to interest chemical companies in developing facilities to rehydrogenate the borax into sodium borohydride" says Moore.

In addition, the Bush administration's new Freedom Car effort to push fuel-cell development will lend muscle to solving the distribution and storage problems with hydrogen fuel - and could boost the borax fuel cell in the process.

Daimler-Benz in Germany has led the way toward fuel-cell cars since the 1980s. Now Chrysler, which had worked on its own fuel cells in the United States government's Partnership for a New Generation of Vehicles, has benefited from Daimler's research. Toyota and Honda have also displayed running fuel-cell concept cars and promised to put them into production.

Building fuel-cell cars is one thing. But marketing them to the public with no corner hydrogen stations is another.

Without government standards on fuels, these clean cars from any continent will be sold only to commercial customers who can provide their own refueling infrastructure.

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