Researchers Make Hydrogen From Ethanol
Engineers at the University of Minnesota say they have invented the first reactor capable of producing hydrogen from a renewable fuel source efficiently enough to hold economic potential. The reactor runs on ethanol.
When coupled with a hydrogen fuel cell, a unit small enough to hold in your hand could generate one kilowatt of power, almost enough to supply an average home, the researchers say.
The work will be published in the February 13 issue of the journal “Science” and the researchers say the technology is poised to remove a major stumbling block to the hydrogen economy – no free hydrogen exists, except what is made at high cost from fossil fuels.
Hydrogen is now produced exclusively by a process called steam reforming, which requires very high temperatures and large furnaces.
Hydrogen produced that way is unsuitable for any application except large scale refineries, said Lanny Schmidt, a University of Minnesota chemical engineering professor and the leader of the ethanol reactor study.
“The hydrogen economy means cars and electricity powered by hydrogen,” said Schmidt. “But hydrogen is hard to come by. You cannot pipe it long distances. There are a few hydrogen fueling stations, but they strip hydrogen from methane – natural gas – on site. It is expensive, and because it uses fossil fuels, it increases carbon dioxide emissions, so this is only a short term solution until renewable hydrogen is available.”
The researchers say ethanol is easy to transport and relatively nontoxic. Ethanol produced from corn is used in car engines today.
If ethanol were used instead to produce hydrogen for a fuel cell, the whole process would be nearly three times as efficient, Schmidt and his team say. A bushel of corn would yield three times as much power if its energy were channeled into hydrogen fuel cells rather than burned in a mixture with gasoline.
The invention rests on two innovations: a catalyst based on the metals rhodium and ceria, and an automotive fuel injector that vaporizes and mixes the ethanol-water fuel.
The vaporized fuel mixture is injected into a tube that contains a porous plug made from rhodium and ceria.
The fuel mixture passes through the plug and emerges as a mixture of hydrogen, carbon dioxide and minor products.
The reaction takes only 50 milliseconds and eliminates the flames and soot that commonly accompany ethanol combustion.
In a typical ethanol-water fuel mixture, one could ideally get five molecules of hydrogen for each molecule of ethanol; reacting ethanol alone would yield three hydrogen molecules. The Schmidt team has so far harvested four hydrogen molecules per ethanol molecule.
Provided by theEnvironmental News Service.