Turning to Hydrogen for Energy is Harder Than It Looks

Fuel cell car could emit more CO2 per mile than gasoline counterpart if powered from the grid

Published: 14-Nov-2003

ONG>WASHINGTON Widespread hydrogen use has been enthusiastically embraced by corporations and environmentalists as a panacea for global warming and the depletion of fossil fuels.

Next week the Bush administration is bringing energy ministers of 15 countries to Washington for a meeting on hydrogen, and President George W. Bush pledged in his 2003 State of the Union address that "the first car driven by a child born today could be powered by hydrogen, and pollution-free."

But skeptics, and even some hydrogen advocates, say the use of hydrogen could instead make the air dirtier and the planet warmer. Hydrogen is only a place to store energy. Where the energy comes from in the first place is where the problems start.

The most ambitious use of hydrogen is in a car powered by a fuel cell, a batterylike device that turns hydrogen into electricity while emitting only heat and water vapor. Hydrogen can also be burned directly in engines much like those that run on gasoline, but the Energy Department goal is fuel cells because they get twice as much work out of a pound of hydrogen.

Companies and universities in North America are intensely researching development of a practical fuel cell.

The main source for hydrogen is natural gas, which is in short supply, is cumbersome to convert and may have better uses. Waiting in the wings is coal, burned in old power plants around the world that are already the focus of a dispute over their emissions.

The long-term hope is to make hydrogen from emission-free "renewable" technologies, like windmills or solar cells. In fact, hydrogen may be an essential step to translate the energy of wind or sunlight into power to turn a car's wheels, experts say. But electricity from renewable technologies is costly. At Sharp Solar, which says it is the world's largest maker of solar cells, the general manager, Ronald Kenedi, said it was possible that the energy source to produce hydrogen for vehicles would initially not be the sun or wind. "The first stop on the hydrogen trail will be coal," he said.

A likely source of hydrogen is from a machine called an electrolyzer, which is like a fuel cell in reverse. The fuel cell combines oxygen from the air with hydrogen to produce an electric current, with water as a byproduct, while an electrolyzer runs an electric current through water to split the water molecule into its constituent hydrogen and oxygen atoms. The problem is that if the electricity came off the national power grid to run an electrolyzer, about half of it, on average, would be generated by coal.

The president's proposal contained an implicit recognition that a big part of the fuel-cell question is the fuel. He called for spending $1.2 billion on hydrogen to include money for production, delivery and storage. Another problem is emissions. According to the Energy Department, an ordinary gasoline-powered car emits 374 grams of carbon dioxide per mile, or 1.6 kilometers, it is driven, counting the energy used to make the gasoline and deliver it. The same car powered by a fuel cell would emit nothing, but if the energy required to make the hydrogen came from the electric grid, the emissions would be 436 grams per mile. Similarly, the car would not emit nitrogen oxides, a precursor of smog, but the power plant would.



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