NextEra bets on new power generator that runs without combustion

Mainspring Linear Generator Image: Mainspring Energy website

Startup Mainspring Energy Inc. has landed a $150 million deal with a unit of renewable giant NextEra Energy Inc. to deploy a little known power-generation technology that could help businesses avoid grid outages.

Called a linear generator, it uses a non-combustion reaction of air and fuel to move magnets back and forth through copper coils, generating an electric current. In a video illustration on Mainspring’s website, it looks something like a constantly moving pogo stick lying on its side.

Mainspring’s generators are the latest technology targeting businesses that want to cut their greenhouse-gas emissions and generate their own power at the same time, shielding themselves from the kind of blackouts that have recently struck Texas and California. Packed into box-like units the size of a parking space, they can ramp up to full power within seconds and run on natural gas, biogas or hydrogen, which offers the possibility of lower-carbon or carbon-free electricity produced on-site.

NextEra Energy Resources, a unit of the world’s largest investor-owned producer of wind and solar power, plans to install the generators at NextEra customer facilities. The chance to tap NextEra’s extensive customer network would boost any startup. But for Mainspring, the introduction could be doubly important, convincing potential customers to try a technology they’ve never heard of before.

“It is a really new type of generation,” said founder and chief executive officer Shannon Miller in an interview. “We often get lumped into being an engine or being a fuel cell. The characteristics are different. The value proposition is different.”

Mainspring’s generators will likely appeal to the same customers currently buying fuel cells, but the technologies are quite different. Rather than the electrochemical reaction inside a fuel cell, the generator relies on a low-temperature reaction of pressurized fuel and air that drives linear shafts back and forth through copper coils. Two generators packaged together into a single 20 foot-long container can produce 250 kilowatts of electricity. They can power a building or be plugged directly into the grid.

“Mainspring is able to integrate clean, onsite generation with both renewables and the grid, and we’re pleased to support bringing this innovative product to market,” said NextEra Energy Resources chief executive officer John Ketchum, in a press release.

The Silicon Valley company has raised more than $130 million from such investors as Bill Gates, Equinor Ventures, KCK, Khosla Ventures and utility company American Electric Power Co., Miller said. In addition to the NextEra deal, the company says a national supermarket chain has agreed to install the generators at as many as 30 stores. Miller estimates a typical grocery store could save 10 per cent to 20 per cent on electricity using the generator, when compared with the cost of relying solely on the grid.

Pilot deployments with multiple Fortune 500 companies began last June, according to Mainspring.

Mark McCullough, executive vice president for energy delivery at American Electric Power, said his company was impressed with the generator’s low costs, low emissions and “dispatchability,” the ability to supply power whenever needed. Solar and wind energy are famously dependent on the weather and time of day, while fuel cells, he said, take substantially longer than the generator to reach full power.

“It all rises up to a very usable machine, in many ways,” McCullough said. “This offers us some elegant solutions for a number of use cases.”

© 2021 Bloomberg L.P.

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