One step closer to hydrogen economy?
BOSTON — Wanted: A cheap, reliable power source to satisfy energy-hungry industrial superpower. Must also be pollution-free and provide energy security by being domestically abundant. Immediate opening.
While candidates like solar and wind have sent in their résumés, it seems hydrogen is the perfect match to fuel America's energy demands - right?
Well, maybe. President Bush touts a future hydrogen economy, while environmentalists decry it as a red herring to avoid addressing global warming today. But new research may add a fresh angle to the debate.
From the wintry climes of Minnesota, Lanny Schmidt, a University of Minnesota chemist, and three colleagues of his have discovered a process that could leap several of the hurdles facing the hydrogen economy: the high cost of making hydrogen, the impact on global warming of burning hydrogen, and the safe and efficient use of hydrogen in cars.
The new approach, reported in the journal Science last week, offers hope for the cheapest and most efficient method for extracting hydrogen yet.
Because the gas is typically found in compound form, it must be extracted from other elements to be used. The new process extracts the gas from corn-based ethanol using rhodium and ceria, exotic metals needed in the catalytic process.
Currently, extracting hydrogen from natural gas costs $3.60 to $7.05 per kilogram, even with the best technology, a new National Research Council (NRC) report said last week.
But this new technique - confirmed late one night while the scientists waited for a pizza to arrive at the lab - could produce the gas at $1.50 per kilogram. That would put it in the ballpark even with ultracheap conventional sources like coal, Dr. Schmidt says.
The new process could theoretically be used to fuel power plants and automobiles.
"I want to be careful, I don't want to oversell this," Dr. Schmidt says, adding, "Down the road this looks as if it will work."
The most common way of making industrial hydrogen today is by separating it from natural gas through a "steam reforming" process that requires very high temperatures, large furnaces, and a lot of energy.
By contrast, Schmidt's process used a simple fuel injector from an automobile engine inserted into a glass tube - a device about as big as an ear of corn. He and his colleagues sprayed an ethanol-water mix into a warm chamber to vaporize it. When the vapor passed through a porous ceramic plug embedded with the rhodium and ceria catalysts - voilà, hydrogen flowed out the other end. Lots of it.
Schmidt's process is autothermal, meaning it supplies its own heat, he says. Because of that, the equipment is only a hundredth the size of steam- reforming systems and requires far less energy to extract hydrogen from ethanol.
Another plus to Schmidt's approach is that it won't contribute to global warming. When hydrogen is extracted from ethanol and then consumed in a fuel cell, its byproducts - carbon dioxide and water - can be absorbed by the corn crop grown to produce more ethanol. Result: No net gain of carbon dioxide in the atmosphere.
"I think it will be used in rural areas first - off the grid," Schmidt says. "But some day every town in America could have its own power system instead of building a megaplant."
This process could be made to work in automobiles, too, he says. The biggest obstacle facing hydrogen-powered cars is not so much fuel-cell technology, but the ability to create, or store on board, enough hydrogen.
Right now there are two alternatives: keeping canisters of highly compressed hydrogen on board - a prospect that makes those who recall the Hindenburg a little nervous. Or, a "reformer" can be used to extract hydrogen on the fly from a feedstock like natural gas. The output could be burned in an engine - or processed through a fuel cell to generate the car's power.
Unfortunately today's small partial-oxidation reformers haven't worked efficiently enough to produce sufficient high-purity hydrogen for on-board fuel cells, say experts. Schmidt's approach may change that.
"If they can, indeed, produce hydrogen very efficiently from ethanol, that would be a significant breakthrough," says John DeCicco, a senior fellow at Environmental Defense, an environmental group in New York, who has written about fuel-cell technology in automobiles. "One of the biggest problems of fuel-cell-powered cars: storing hydrogen on the vehicle. This research suggests this technical barrier may be solvable."
Overall, he says the University of Minnesota research sounds promising, even if some hurdles remain.
One such hurdle:It would require at least 40 percent of the cropland in the US to produce enough ethanol to power the nation, according to the new NRC report.
The NRC said that while hydrogen could "fundamentally transform the US energy system ... the impacts on oil imports and carbon dioxide emissions are likely to be minor during the next 25 years," even with huge investments. Its findings do not consider the new technique.
Environmentalists point out that pure ethanol - of the sort currently burned in automobile engines - requires a lot of energy and money to produce before it ever gets to Schmidt's clever process.
Schmidt agrees - but says the lion's share of the cost of making ethanol flows from the cost of extracting every drop of water from it.
His system for powering cars - which would not burn the hydrogen in an engine but run it through a fuel cell for electricity - does not require pure ethanol, but actually works better with watered-down ethanol.
Amory Lovins, CEO of the Rocky Mountain Institute, says a key part of the solution is designing lighter cars that run on hydrogen. He is trying to make cars out of carbon fiber - rather than requiring futuristic hydrogen fuel cells to shove tons of metal down the highway. "This research is headed the right direction," Mr. Lovins says. "If you combine those efficiencies with a light, but safe vehicle" then hydrogen might compete better economically with today's fuels.
Some researchers hope that hydrogen eventually will be used to power America. Hydrogen also is:
• a colorless, odorless, tasteless, and nonpoisonous gas under normal condition on Earth, but it is highly flammable.
• the most abundant element in the universe, accounting for 90 percent of the universe by weight. It is rarely found in its pure form since it readily combines with other elements.
• a more efficient fuel source than conventional sources. The amount of energy produced by hydrogen per unit weight of fuel is about three times the amount of energy contained in an equal weight of gasoline, and almost seven times that of coal.
• Its combustion produces no carbon dioxide or sulfur emissions. Hydrogen can produce nitrous oxide under some conditions.
SOURCE: The National Hydrogen Association