Hydrogen From Corn | Green Energy News

February 8, 2004 – Vol.8 No.46

HYDROGEN FROM CORN.

Researchers at the University of Minnesota have invented a reactor that can extract hydrogen from ethanol. If the reactor proves itself in the long run, it could be considered a major leap towards a hydrogen economy.

While hydrogen fuel cells have been improving rapidly - such as Honda’s development of a fuel cell that can work in sub-freezing temperatures - the supply and transportation of hydrogen has become a major stumbling block.

The reactor, that was developed by a team of researchers led by Lanny Schmidt, Regents Professor of Chemical Engineering at the University, can supply on-demand hydrogen for a fuel cell that could provide about one kilowatt of power.

In this process no hydrogen storage is necessary as hydrogen is generated as needed. The device is small enough and light enough - about 2 feet long - to be held in one hand. Its small size makes dreamers immediately think of automotive applications, though the researchers are only considering residential power for now.

(However, its output capacity would have to be increased for home use. The researchers considered that one kilowatt would be ample for residential power, but in reality 5-7 kilowatts might be a better goal. Cars, of course, would need in excess of 50 kilowatts.)

Ethanol as a source of hydrogen is particularly appealing. Of the two alcohols, ethanol and methanol, considered as a source of hydrogen for fuel cells, ethanol would be preferable since it is considered non-toxic.

Ethanol is easier and safer to transport than hydrogen. It could be trucked as gasoline is now as an ambient temperature liquid, but safer as in the case of an accident or spill as it degrades quickly, is soluble in water, and doesn’t contaminate soil.

Ethanol is also considered carbon neutral. The carbon dioxide released from the reactor would be recaptured in equivalent amounts in the next growing season. Any carbon dioxide released in the production of the ethanol would have to be accounted for, however.

Ethanol, too, though derived now mostly from corn, may someday be available in the form of bioethanol derived from other feedstocks such as switch grass. The development of bioethanol would expand the production capacity for ethanol beyond corn producing regions.

The researchers also say that biodiesel could be used as source of hydrogen in similar reactors.

Dr. Schmidt also said in news reports, that using corn sugar to make ethanol for a source of hydrogen for fuel cells could yield 50 percent of the energy content of the sugar, while burning ethanol from the same sugar as fuel yields only 20 percent of its energy. Overall, energy conversion efficiency using hydrogen from corn sugars in a fuel cell would be 60 percent.

The reactor doesn’t require pure ethanol. Some water content in the ethanol is acceptable as the process strips the hydrogen from the ethanol as well as the water.

The invention utilizes a catalyst made of the metals rhodium and ceria. The alcohol is injected via an off-the-shelf automotive fuel injector into a tube containing a porous plug made of the two metals and emerges on the other side as hydrogen, carbon dioxide and minor by-products. The reaction takes only 50 milliseconds thus would fit the quick start-up time required for vehicular applications.

As with all developments, time and patience are needed for proving, testing, further research and development. It may work. It may not.

Visit the Lanny Schmidt Group at the University of Minnesota at http://www1.cems.umn.edu/research/schmidt The research article for the reactor appeared in Science magazine at http://www.sciencemag.org/ (subscription required)