[extropy-chat] hydrogen reactor claim

[Damien Broderick]

New Reactor Puts Hydrogen From Renewable Fuels Within Reach

University of Minnesota

The first reactor capable of producing hydrogen from a renewable fuel 
source--ethanol--efficiently enough to hold economic potential has been 
invented by University of Minnesota engineers. When coupled with a hydrogen 
fuel cell, the unit--small enough to hold in your hand--could generate one 
kilowatt of power, almost enough to supply an average home, the researchers 
said. The technology is poised to remove the major stumbling block to the 
"hydrogen economy": no free hydrogen exists, except what is made at high 
cost from fossil fuels. The work will be published in the Feb. 13 issue of 
Science.

The researchers see an early use for their invention in remote areas, where 
the installation of new power lines is not feasible. People could buy 
ethanol and use it to power small hydrogen fuel cells in their basements. 
The process could also be extended to biodiesel fuels, the researchers 
said. Its benefits include reducing dependence on imported fuels, reducing 
carbon dioxide emissions (because the carbon dioxide produced by the 
reaction is stored in the next year's corn crop) and boosting rural economies.

Hydrogen is now produced exclusively by a process called steam reforming, 
which requires very high temperatures and large furnaces--in other words, a 
huge input of energy. It's unsuitable for any application except 
large-scale refineries, said Lanny Schmidt, Regents Professor of Chemical 
Engineering, who led the effort. Working with him were scientist Gregg 
Deluga, first author of the Science paper, and graduate student James 
Salge. All three are in the university's department of chemical engineering 
and materials science.

"The hydrogen economy means cars and electricity powered by hydrogen," said 
Schmidt. "But hydrogen is hard to come by. You can't pipe it long 
distances. There are a few hydrogen fueling stations, but they strip 
hydrogen from methane--natural gas--on site. It's 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."

Ethanol is easy to transport and relatively nontoxic. It is already being 
produced from corn and used in car engines. But if it were used instead to 
produce hydrogen for a fuel cell, the whole process would be nearly three 
times as efficient. That is, a bushel of corn would yield three times as 
much power if its energy were channeled into hydrogen fuel cells rather 
than burned along with gasoline.

"We can potentially capture 50 percent of the energy stored in sugar [in 
corn], whereas converting the sugar to ethanol and burning the ethanol in a 
car would harvest only 20 percent of the energy in sugar," said Schmidt. 
"Ethanol in car engines is burned with 20 percent efficiency, but if you 
used ethanol to make hydrogen for a fuel cell, you would get 60 percent 
efficiency."

The difference, Deluga explained, is due in large part to the need to 
remove all the water from ethanol before it can be put in an automobile gas 
tank--and the last drops of water are the hardest to remove. But the new 
process doesn't require pure ethanol; in fact, it strips hydrogen from both 
ethanol and water, yielding a hydrogen bonus.

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. So far, the Schmidt team has 
harvested four hydrogen molecules per ethanol molecule.

"We're confident we can improve this technology to increase the yield of 
hydrogen and use it to power a workable fuel cell," said Salge.