Future vehicles and electric generators powered by fuel cells could eventually run on hydrogen derived from corn. Researchers at the University of Minnesota, Twin Cities, have come up with an efficient method of converting ethanol, the alcohol produced by the fermentation of corn, into hydrogen fuel.
From the breakdown of biomass to the splitting of water using solar energy, researchers around the world have been exploring a host of renewable sources of hydrogen (SN: 10/12/02, p. 235: Hydrogen: The Next Generation). The main source of hydrogen today is natural gas—a polluting and nonrenewable fossil fuel.
To extract hydrogen from ethanol, Lanny Schmidt and his coworkers injected a mixture of water and ethanol into a palm-size reaction chamber heated to 140°C. The ethanol and water mixed with air inside the chamber and passed through a porous membrane covered with rhodium and cerium oxide catalysts. As the catalysts stripped the hydrogen atoms from the ethanol, the process generated heat, which significantly sped up the reaction.
Just 50 milliseconds after the initial injection of the water-ethanol mixture, essentially all the hydrogen atoms in ethanol had been converted into hydrogen fuel. Some of the hydrogen atoms from water in the mixture were also extracted and contributed to the overall volume of hydrogen fuel.
The scientists calculate that their hydrogen-generating system could capture more than 50 percent of the energy that plants store in the form of sugar. Approximately two shot glasses of ethanol could yield enough hydrogen to generate 350 watt-hours of electricity, enough to power half a dozen 60-watt lightbulbs for an hour.
The researchers describe their reactor in the Feb. 13 Science.
Gregg A. Deluga
Department of Chemical Engineering and Materials Science
University of Minnesota
151 Amund Hall
421 Washington Avenue, SE
Minneapolis, MN 55455