"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.
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.
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.
The engineers were surprised to learn late last year, 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."
"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.
