ReVolt engineers are working on a new design in which a zinc slurry is pumped through tubes that act as an air electrode, causing the chemical reaction that produces a current, McDougall explained. He expects it will take four or five years to commercialize the technology for large-scale applications, such as grid storage.

The company has raised 24 million Euros in funding, including an investment from power generator RWE of Germany, which is looking at the zinc air for storage on the electricity grid. ReVolt has applied for an ARPA-E grant aimed at breakthrough energy technologies but was not chosen in the first round of awards.

For vehicles, it makes sense to combine the relatively large energy storage of zinc air batteries with other storage technologies, McDougall said. Power-dense lithium ion batteries could be used for boosts of acceleration and ultracapacitors could capture energy from regenerative braking.

"You could increase the range of next-generation of electric vehicles with hybrid storage... You could get three times the range, eliminate the safety concerns, and cut the cost of the system," he said.

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