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Technique turns ash into hydrogen gas

Bowl of ash
Ash leftover from burning household waste is being used to produce hydrogen gas, which can then power cars and generate electricity.Lund University

Piles of ash leftover from incinerated trash may be a viable source of hydrogen gas that can be used to generate electricity and power cars, suggests a process pioneered in a research lab.

The trick? Just add water, which reacts with residual metallic aluminum in the ash, explained Aamir Ilyas, a water resource engineer at Lund University in Sweden, who developed the technique.

The aluminum comes from soda cans, milk cartons and other food packaging that gets tossed out with the household waste destined for the incinerator.

Image of Aamir Ilyas in the lab
Aamir Ilyas, a water resource engineer at Lund University, pioneered the gas from ash technique for his thesis.Lund University

"During the incineration, this aluminum packaging gets converted into metal lumps and fine particles, which later become the source of hydrogen producing reactions," Ilyas told NBC News in an email.

The reaction takes place in an oxygen-free environment. The produced gas is sucked up through pipes and stored in tanks. "The process does not consume any energy and works at room temperature," he said.

In Sweden, where trash incineration is a common waste management technique, about 1 million tons of this ash are piled up each year, sufficient to produce enough hydrogen to supply 11,000 homes with electricity.

"The leftover moist ash can be treated by leaving it in open-air or well-aerated storage for a few weeks. Then it can be safely disposed as construction material for covering older landfills," Ilyas said.

While the potential of the technique is "very good," added Ilyas, "we will have to demonstrate it at a bigger scale before it can be a viable energy recovery technique."

The engineer developed the technique for his thesis.

John Roach is a contributing writer for NBC News. To learn more about him, visit his website.