Jerry Woodall, centre, a professor at Purdue University along with Charles Allen, holding test tube, and Jeffrey Ziebarth, both doctoral students, demonstrate their method for producing hydrogen by adding water to an alloy of aluminium and gallium. The hydrogen could then be used to run an internal combustion engine
Pellets made out of aluminium and gallium can produce pure hydrogen when water is poured on them, offering a possible alternative to petrol-powered engines, US scientists say.
Hydrogen is seen as the ultimate in clean fuels, especially for powering cars, because it emits only water when burned, but researchers have not yet found the most efficient way to produce and store hydrogen.
The metal compound pellets may offer a way, said Jerry Woodall, an engineering professor at Purdue University in Indiana who invented the system.
The hydrogen is generated on demand, so you only produce as much as you need when you need it,” Woodall said. He said the hydrogen would not have to be stored or transported, taking care of two stumbling blocks to generating hydrogen.
For now, the Purdue scientists think the system could be used for smaller engines like lawn mowers and chain saws. But they think it would work for cars and trucks as well, either as a replacement for petrol or as a means of powering hydrogen fuel cells.
“It is one of the more feasible ideas out there,” Jay Gore, an engineering professor and interim director of the Energy Centre at Purdue’s Discovery Park, said on Thursday. “It’s a very simple idea but had not been done before.”
On its own, aluminium will not react with water because it forms a protective skin when exposed to oxygen. Adding gallium keeps the film from forming, allowing the aluminium to react with oxygen in the water.
This reaction splits the oxygen and hydrogen contained in water, releasing hydrogen in the process.
“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.”
What is left over is aluminium oxide and gallium. In the engine, the byproduct of burning hydrogen is water. “No toxic fumes are produced,” Woodall said.
“When and if fuel cells become economically viable, our method would compete with petrol price-wise.”
Recycling the aluminium oxide by-product and developing a lower grade of gallium could bring down costs, making the system more affordable, Woodall said.
The Purdue Research Foundation holds title to the primary patent, which has been filed with the US Patent and Trademark Office. USA, Indiana-based start-up company, AlGalCo LLC, has received a license for the exclusive right to commercialise the process.