Gallium and aluminum tigers in your tank?

An Indiana startup called AlGalCo is to commercialize a Purdue University research development that extracts hydrogen from water using aluminum and gallium as catalysts.

Researchers say the process could provide hydrogen-on-demand for fuel cells or internal combustion engines, with the possibility of replacing gasoline.

The method makes it unnecessary to store or transport hydrogen—two major challenges in creating a hydrogen economy, said Jerry Woodall, a professor of electrical and computer engineering at Purdue who first invented the process while working as a researcher in the semiconductor industry in 1967.

"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.

Woodall and student researchers (photo) >

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 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.

The oxygen and hydrogen contained in water split, 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, but AlGalCo LLC, a self-funded company according to co-founder and CEO Kurt Koehler, has received a license for the exclusive right to commercialize the process. Koehler told the Cleantech Group it is in the midst of testing a second prototype, the results of which should hopefully be ready for release in early September of this year.

Woodall says it was by accident that he discovered the process while working as a researcher in the semiconductor industry.

"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."

In order for the technology to be economically competitive with gasoline, Woodall says the cost of recycling aluminum oxide must be reduced.

"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 alumina using a process called fused salt electrolysis, he said. 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.

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, he said.

"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 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."

"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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