Posted on 05/17/2007 4:09:52 AM PDT by saganite
WEST LAFAYETTE, INDIANA, USA -- 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. The technique could be used to replace gasoline, though it is not quite cost-competitive yet.
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 waste products are gallium and aluminum oxide, also called alumina. Combusting hydrogen in an engine produces only water as waste.
As a catalyst, the gallium is not consumed, and hence does not need to be replenished. The alumina can be recharged in a separate process, preferably using renewable energy.
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.
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."
"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.
Can you please correct my title. On demand hydrogen for cars should be in brackets as that is not part of the title. Thanks
AH, finally, a use for old beer cans!
This sounds good on the surface, but 100% of aluminum is refined by electrolytic means. Are they counting this in the equation or is this just another bandwagon for liberals to jump on?
I think the article mentions nuclear power as a source for producing the aluminum.
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.
Liquid aluminum reacts very violently with oxygen, it's several times more explosive than TNT. The heat energy produced from that reaction might be tappable as well.
-Eric
Sooner or later, they’re going to sort it out. Sooner, I hope.
Liberals wouldn't go near it. It might work.
So where's the savings? I already get around 450-480 miles to a tankfull of gas and even at $3 a gallon it still only costs around $50 to fill up.
I can just imagine the first time one of these cars gets into a collision, the tank splits open, and some fireman tries turning his water hose on it
Like all hydrogen fuel schemes, the gotcha is in where do you get the energy to produce the hydrogen. currently there isn't much in the way of spare capacity on the US electrical system, so you'd have to build new generation to handle the energy needs. I read somewhere that it would take about 200 new nuclear plants to provide the energy used by the transportation sector. Another example (this "research") of taxpayer money paying for something we don't want and can't use.
Are you sure about that? I've handled molten aluminium to make small castings, and I'm sure it has come in contact with the oxygen in air. I do know that aluminium powder is a component of the explosive Astrolite, but that requires another exotic chemical, to be produced. This Astrolite is about twice as explosive as TNT. Perhaps you've confused the latter for the former, no?
No savings are involved. This isn’t about cheaper fuel but less polluting fuel.
The article continuously compares this to gasoline, but in fact this amounts to a type of battery technology. If it's advantageous, it is so not in comparison to gasoline but to other ways of storing electrical power.All discussion of a "hydrogen economy" boil down to that, since hydrogen is not available from any source other than a carbon-containing chemical fuel or directly from electricity.
Did you read the entire article? The hydrogen is produced on demand in the vehicle by taking advantage of the chemical reaction discussed.
I guess they won’t be using an aluminum engine block for this lol...
I can see it now. We bring the pellets home in big bags like the Purina pet chow until the Chinese sneak some melamine in to poison our cars. :)
And about a renewable fuel that isn't in primarily in the hands of a few despotic regimes around the world.
If this process has potential, and can displace a percentage of demand for oil in conjunction with other technologies, it can have a beneficial effect on segments of the market that aren't suitable for anything BUT gasoline by reducing demand. Any (economically-viable) step toward reduction of demand has benefits toward stabilizing price and reducing the power of certain evil regimes around the world. That much works for me.
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