[tt] Aluminum/Gallium Pellets produce pure hydrogen from h20

[Isabelle Hakala]

http://www.physorg.com/news98556080.html

New process generates hydrogen from aluminum alloy to run engines,  
fuel cells Discussion at PhysOrgForum
Purdue researchers demonstrate their method for producing hydrogen by  
adding water to an alloy of aluminum and gallium. The hydrogen could  
then be used to run an internal combustion engine. The reaction was  
discovered by Jerry Woodall center a distin ...
Purdue researchers demonstrate their method for producing hydrogen by  
adding water to an alloy of aluminum and gallium. The hydrogen could  
then be used to run an internal combustion engine. The reaction was  
discovered by Jerry Woodall, center, a distinguished professor of  
electrical and computer engineering. Charles Allen, holding test  
tube, and Jeffrey Ziebarth, both doctoral students in the School of  
Electrical and Computer Engineering, are working with Woodall to  
perfect the process. (Purdue News Service photo/David Umberger)

A Purdue University engineer has developed a method that uses an  
aluminum alloy to extract hydrogen from water for running fuel cells  
or internal combustion engines, and the technique could be used to  
replace gasoline.
The method makes it unnecessary to store or transport hydrogen - two  
major challenges in creating a hydrogen economy, said Jerry Woodall,  
a distinguished professor of electrical and computer engineering at  
Purdue who invented the process.

"The hydrogen is generated on demand, so you only produce as much as  
you need when you need it," said Woodall, who presented research  
findings detailing how the system works during a recent energy  
symposium at Purdue.

The technology could be used to drive small internal combustion  
engines in various applications, including portable emergency  
generators, lawn mowers and chain saws. The process could, in theory,  
also be used to replace gasoline for cars and trucks, he said.

Hydrogen is generated spontaneously when water is added to pellets of  
the alloy, which is made of aluminum and a metal called gallium. The  
researchers have shown how hydrogen is produced when water is added  
to a small tank containing the pellets. Hydrogen produced in such a  
system could be fed directly to an engine, such as those on lawn mowers.

"When water is added to the pellets, the aluminum in the solid alloy  
reacts because it has a strong attraction to the oxygen in the  
water," Woodall said.

This reaction splits the oxygen and hydrogen contained in water,  
releasing hydrogen in the process.

The gallium is critical to the process because it hinders the  
formation of a skin normally created on aluminum's surface after  
oxidation. This skin usually prevents oxygen from reacting with  
aluminum, acting as a barrier. Preventing the skin's formation allows  
the reaction to continue until all of the aluminum is used.

The Purdue Research Foundation holds title to the primary patent,  
which has been filed with the U.S. Patent and Trademark Office and is  
pending. An Indiana startup company, AlGalCo LLC., has received a  
license for the exclusive right to commercialize the process.

The research has been supported by the Energy Center at Purdue's  
Discovery Park, the university's hub for interdisciplinary research.

"This is exactly the kind of project that suits Discovery Park. It's  
exciting science that has great potential to be commercialized," said  
Jay Gore, associate dean of engineering for research, the Energy  
Center's interim director and the Vincent P. Reilly Professor of  
Mechanical Engineering.

The research team is made up of electrical, mechanical, chemical and  
aeronautical engineers, including doctoral students.

Woodall discovered that liquid alloys of aluminum and gallium  
spontaneously produce hydrogen if mixed with water while he was  
working as a researcher in the semiconductor industry in 1967. The  
research, which focused on developing new semiconductors for  
computers and electronics, led to advances in optical-fiber  
communications and light-emitting diodes, making them practical for  
everything from DVD players to automotive dashboard displays. That  
work also led to development of advanced transistors for cell phones  
and components in solar cells powering space modules like those used  
on the Mars rover, earning Woodall the 2001 National Medal of  
Technology from President George W. Bush.

"I was cleaning a crucible containing liquid alloys of gallium and  
aluminum," Woodall said. "When I added water to this alloy - talk  
about a discovery - there was a violent poof. I went to my office and  
worked out the reaction in a couple of hours to figure out what had  
happened. When aluminum atoms in the liquid alloy come into contact  
with water, they react, splitting the water and producing hydrogen  
and aluminum oxide.

"Gallium is critical because it melts at low temperature and readily  
dissolves aluminum, and it renders the aluminum in the solid pellets  
reactive with water. This was a totally surprising discovery, since  
it is well known that pure solid aluminum does not readily react with  
water."

The waste products are gallium and aluminum oxide, also called  
alumina. Combusting hydrogen in an engine produces only water as waste.

"No toxic fumes are produced," Woodall said. "It's important to note  
that the gallium doesn't react, so it doesn't get used up and can be  
recycled over and over again. The reason this is so important is  
because gallium is currently a lot more expensive than aluminum.  
Hopefully, if this process is widely adopted, the gallium industry  
will respond by producing large quantities of the low-grade gallium  
required for our process. Currently, nearly all gallium is of high  
purity and used almost exclusively by the semiconductor industry."

Woodall said that because the technology makes it possible to use  
hydrogen instead of gasoline to run internal combustion engines it  
could be used for cars and trucks. In order for the technology to be  
economically competitive with gasoline, however, the cost of  
recycling aluminum oxide must be reduced, he said.

"Right now it costs more than $1 a pound to buy aluminum, and, at  
that price, you can't deliver a product at the equivalent of $3 per  
gallon of gasoline," Woodall said.

However, the cost of aluminum could be reduced by recycling it from  
the alumina using a process called fused salt electrolysis. The  
aluminum could be produced at competitive prices if the recycling  
process were carried out with electricity generated by a nuclear  
power plant or windmills. Because the electricity would not need to  
be distributed on the power grid, it would be less costly than power  
produced by plants connected to the grid, and the generators could be  
located in remote locations, which would be particularly important  
for a nuclear reactor to ease political and social concerns, Woodall  
said.

"The cost of making on-site electricity is much lower if you don't  
have to distribute it," Woodall said.

The approach could enable the United States to replace gasoline for  
transportation purposes, reducing pollution and the nation's  
dependence on foreign oil. If hydrogen fuel cells are perfected for  
cars and trucks in the future, the same hydrogen-producing method  
could be used to power them, he said.

"We call this the aluminum-enabling hydrogen economy," Woodall said.  
"It's a simple matter to convert ordinary internal combustion engines  
to run on hydrogen. All you have to do is replace the gasoline fuel  
injector with a hydrogen injector."

Even at the current cost of aluminum, however, the method would be  
economically competitive with gasoline if the hydrogen were used to  
run future fuel cells.

"Using pure hydrogen, fuel cell systems run at an overall efficiency  
of 75 percent, compared to 40 percent using hydrogen extracted from  
fossil fuels and with 25 percent for internal combustion engines,"  
Woodall said. "Therefore, when and if fuel cells become economically  
viable, our method would compete with gasoline at $3 per gallon even  
if aluminum costs more than a dollar per pound."

The hydrogen-generating technology paired with advanced fuel cells  
also represents a potential future method for replacing lead-acid  
batteries in applications such as golf carts, electric wheel chairs  
and hybrid cars, he said.

The technology underscores aluminum's value for energy production.

"Most people don't realize how energy intensive aluminum is," Woodall  
said. "For every pound of aluminum you get more than two kilowatt  
hours of energy in the form of hydrogen combustion and more than two  
kilowatt hours of heat from the reaction of aluminum with water. A  
midsize car with a full tank of aluminum-gallium pellets, which  
amounts to about 350 pounds of aluminum, could take a 350-mile trip  
and it would cost $60, assuming the alumina is converted back to  
aluminum on-site at a nuclear power plant.

"How does this compare with conventional technology? Well, if I put  
gasoline in a tank, I get six kilowatt hours per pound, or about two  
and a half times the energy than I get for a pound of aluminum. So I  
need about two and a half times the weight of aluminum to get the  
same energy output, but I eliminate gasoline entirely, and I am using  
a resource that is cheap and abundant in the United States. If only  
the energy of the generated hydrogen is used, then the aluminum- 
gallium alloy would require about the same space as a tank of  
gasoline, so no extra room would be needed, and the added weight  
would be the equivalent of an extra passenger, albeit a pretty large  
extra passenger."

The concept could eliminate major hurdles related to developing a  
hydrogen economy. Replacing gasoline with hydrogen for transportation  
purposes would require the production of huge quantities of hydrogen,  
and the hydrogen gas would then have to be transported to filling  
stations. Transporting hydrogen is expensive because it is a "non- 
ideal gas," meaning storage tanks contain less hydrogen than other  
gases.

"If I can economically make hydrogen on demand, however, I don't have  
to store and transport it, which solves a significant problem,"  
Woodall said.

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