 |
There are currently, 279 guest(s) and 0 member(s) that are online.
You are Anonymous user. You can register for free by clicking here
| |
| |
New aluminum-rich alloy produces hydrogen on-demand for large-scale uses
Posted on Tuesday, February 19, 2008 @ 22:58:45 UTC by vlad
|
|
Purdue University engineers have developed a new aluminum-rich alloy
that produces hydrogen by splitting water and is economically
competitive with conventional fuels for transportation and power
generation.
"We now have an economically
viable process for producing hydrogen on-demand for vehicles,
electrical generating stations and other applications," said Jerry
Woodall, a distinguished professor of electrical and computer
engineering at Purdue who invented the process.
The new alloy contains 95
percent aluminum and 5 percent of an alloy that is made of the metals
gallium, indium and tin. Because the new alloy contains significantly
less of the more expensive gallium than previous forms of the alloy,
hydrogen can be produced less expensively, he said.
When immersed in water, the alloy splits water molecules into
hydrogen and oxygen, which immediately reacts with the aluminum to
produce aluminum oxide, also called alumina, which can be recycled back
into aluminum. Recycling aluminum from nearly pure alumina is less
expensive than mining the aluminum-containing ore bauxite, making the
technology more competitive with other forms of energy production,
Woodall said.
"After recycling both the aluminum oxide back to aluminum and the
inert gallium-indium-tin alloy only 60 times, the cost of producing
energy both as hydrogen and heat using the technology would be reduced
to 10 cents per kilowatt hour, making it competitive with other energy
technologies," Woodall said.
The researchers will present findings about the new alloy on Feb.
26 during the conference Materials Innovations in an Emerging Hydrogen
Economy, which runs Feb. 24-27 in Cocoa Beach, Fla..
A key to developing the alloy for large-scale technologies is
controlling the microscopic structure of the solid aluminum and the
gallium-indium-tin alloy mixture.
"This is because the mixture tends to resist forming entirely as a
homogeneous solid due to the different crystal structures of the
elements in the alloy and the low melting point of the
gallium-indium-tin alloy," Woodall said.
The alloy is said to have two phases because it contains abrupt changes in composition from one constituent to another.
"I can form a one-phase melt of liquid aluminum and the
gallium-indium-tin alloy by heating it. But when I cool it down, most
of the gallium-indium-tin alloy is not homogeneously incorporated into
the solid aluminum, but remains a separate phase of liquid," Woodall
said. "The constituents separate into two phases just like ice and
liquid water."
The two-phase composition seems to be critical for the technology
to work because it enables the aluminum alloy to react with water and
produce hydrogen.
The researchers had earlier discovered that slow-cooling and
fast-cooling the new 95/5 aluminum alloy produced drastically different
versions. The fast-cooled alloy contained aluminum and the
gallium-indium-tin alloy apparently as a single phase. In order for it
to produce hydrogen, it had to be in contact with a puddle of the
liquid gallium-indium-tin alloy.
"That was a very exciting finding because it showed that the alloy
would react with water at room temperature to produce hydrogen until
all of the aluminum was used up," Woodall said.
The engineers were surprised
to learn late last year, however, that slow-cooling formed a two-phase
solid alloy, meaning solid pieces of the 95/5 aluminum alloy react with
water to produce hydrogen, eliminating the need for the liquid
gallium-indium-tin alloy.
"That was a fantastic discovery," Woodall said. "What used to be a curiosity is now a real alternative energy technology."
The research is partially funded by Purdue's Energy Center at the university's Discovery Park.
"This technology has exciting potential, and I hope that it
receives a fair and detailed evaluation and consideration from the
scientific, government and business communities," said Jay Gore, the
Vincent P. Reilly Professor of Mechanical Engineering and interim
director of the Energy Center.
The slow-cooling technique made it possible to create forms of the alloy containing higher concentrations of aluminum.
The Purdue researchers are developing a method to create briquettes
of the alloy that could be placed in a tank to react with water and
produce hydrogen on-demand. Such a technology would eliminate the need
to store and transport hydrogen, two potential stumbling blocks in
developing a hydrogen economy, Woodall said.
The gallium-indium-tin alloy component is inert, which means it can
be recovered and reused at an efficiency approaching 100 percent, he
said
"The aluminum oxide is recycled back into aluminum using the
currently preferred industrial process called the Hall-Héroult process,
which produces one-third as much carbon dioxide as combusting gasoline
in an engine," Woodall said.
The aluminum splits water by reacting with the oxygen atoms in
water molecules, liberating hydrogen in the process. The
gallium-indium-tin alloy is a critical component because it hinders the
formation of a "passivating" aluminum oxide skin normally created on
pure aluminum's surface after bonding with oxygen, a process called
oxidation. This skin usually acts as a barrier and prevents oxygen from
reacting with bulk aluminum. Reducing the skin's protective properties
allows the reaction to continue until all of the aluminum is used to
generate hydrogen, Woodall said.
"This skin is like an eggshell," he said. "Think of trying to fry an egg without breaking the shell."
The researchers developed the new alloy in late 2007 and are reporting about it for the first time during the conference.
"We now have a simple process for making 95/5, and we know the
process splits water and produces hydrogen until all of the aluminum
alloy is used up," Woodall said.
For the technology to be used in major applications such as cars
and trucks or for power plants, however, a large-scale recycling
program would be required to turn the alumina back into aluminum and to
recover the gallium-indium-tin alloy. Other infrastructure components,
such as those related to manufacturing and the supply chain, also would
have to be developed, he said.
"So the economic risk is large, but the potential payoff is also
large," said Woodall, who received the 2001 National Medal of
Technology, the nation's highest award for technological achievement.
Aluminum, the most abundant metal on earth, is refined from the raw mineral bauxite, which also contains gallium.
Future research will include work to learn more about the chemical
mechanisms behind the process and the microscopic structure of the
alloy.
Source: Purdue University
Via: http://www.physorg.com/news122655117.html
|
| |
|
Don't have an account yet? You can create one. As a registered user you have some advantages like theme manager, comments configuration and post comments with your name.
| |
Average Score: 4.5
Votes: 2
| |
|
| "New aluminum-rich alloy produces hydrogen on-demand for large-scale uses" | Login/Create an Account | 2 comments | Search Discussion |
|
| | The comments are owned by the poster. We aren't responsible for their content. |
|
|
|
No Comments Allowed for Anonymous, please register |
|
Re: New aluminum-rich alloy produces hydrogen on-demand for large-scale uses (Score: 1)
by Light1 on Wednesday, February 20, 2008 @ 13:32:26 UTC
(User Info | Send a Message) | The Purdue group appear to be unaware of the ongoing work by Alternate Energy Corp. of Burlington, Ontario, CN, aka CleanWatts (see http://www.cleanwatts.com/ [www.cleanwatts.com]). Same technology, e.g., on-demand hydrogen evolution from a proprietary metal/catalyst system. AEC did a proof-of-concept demonstration with a hydrogen-powered golf cart several years ago.
The precedent for these kinds of hydrogen-evolving metal catalyst systems is a material called "Chemalloy." See U.S. patents no. 2,796,345 and 2.927,856 issued to Samuel Freedman in 1957 and assigned to Chemally Electronics Corp. Would recommend that the Purdue researchers do a Google search on Chemalloy. |
|
|
Closing the hydrogen economic loop (Score: 1)
by vlad on Monday, July 21, 2008 @ 23:34:04 UTC
(User Info | Send a Message) http://www.zpenergy.com | The inventor of the nickel metal hydride (NiMH) technology used for
building batteries for countless portable electronic gadgets and now
hybrid gas-electric cars believes the hydrogen economy is already upon
us.
In a paper published in the current issue of the International Journal of Nuclear Hydrogen Production and Applications,
Stanford Ovshinsky, Chairman and CEO of Ovshinsky Innovation LLC, based
in Bloomfield Hills, Michigan, explains that we already have the means
for making the hydrogen economy realistic.
...
More: http://www.physorg.com/news135848971.html [www.physorg.com]
|
|
|
|
|
