Scientists create fuel source
Reactor uses ethanol to produce hyrdrogen

By Lee Bowman, Scripps Howard News Service
February 13, 2004

Minnesota scientists said they have developed the first reactor capable of producing hydrogen from a renewable fuel source — ethanol — using a device built around an ordinary engine's fuel injector.

"For hydrogen to really become economical, we need a safe, portable liquid fuel," said Larry Schmidt, a professor of chemical engineering at the University of Minnesota-Twin Cities. "Ethanol is one of the best available."

His team reports today in the journal Science that a self-heating catalyst produces hydrogen from ethanol, water and air at about 60 percent efficiency — generating electricity at about 4 cents a kilowatt hour.

Although hydrogen is by far the most common known element in the universe, no free hydrogen exists — it's all locked up with other elements. The major stumbling block to shifting to a hydrogen-fueled economy has been that it costs four times more than the next-least-expensive fuel, and has to be extracted from fossil fuels — natural gas or coal.

Hydrogen is produced exclusively by a process called steam reforming, which requires very high temperatures and large furnaces, consuming a lot of energy and suitable only for large refineries, Schmidt said.

"Hydrogen is hard to come by," he explained. "You can't pipe it long distances. There are a few hydrogen-fueling stations, but they strip hydrogen from methane — natural gas — on site. And it increases carbon dioxide emissions, so it is only a short-term solution until renewable hydrogen is available."

Ethanol, produced from corn, is already used in car engines. But as a hydrogen source for a fuel cell, the process would be three times more efficient, Schmidt said.

The difference, says researcher Gregg Deluga, first author of the paper, is that all the water needs to be removed from ethanol before it goes in a gas tank, while the new process actually strips hydrogen from both ethanol and water, producing more hydrogen than ethanol would alone.

The invention uses a catalyst made from the metals rhodium and ceria that heats up to a temperature of nearly 1,300 degrees Fahrenheit and converts the ethanol, water and oxygen vaporized by the fuel injector into hydrogen and carbon dioxide. The whole reaction takes only 50 milliseconds, and is much cleaner than ethanol combustion in an engine.

However, the carbon dioxide in the mix means the hydrogen won't work in the type of high-powered fuel cells now being used to power cars, although cells might eventually be adapted.