Mainspring raises USD 290m in Series E round

California-based Mainspring Energy, the maker of energy generators that can switch between biogas, hydrogen, and ammonia, has closed a USD-290-million (EUR 293m) Series E funding round.

Following a first close at USD 150 million in May, the company raised an additional USD 140 million, it said earlier this week. Growth equity investor Lightrock led the round, the participants in which also included Canada Pension Plan Investment Board (CPP Investments), Shell Ventures, Hanwha Power Systems, and other new private investors. Existing investors like Khosla Ventures, Bill Gates, Fine Structure Ventures and Princeville Capital also took part.

Mainspring will use the raised amount to expand operations and scale manufacturing of the Mainspring Linear Generators. In June, the firm announced that the device had passed key tests directly running 100% hydrogen and 100% ammonia fuels at high efficiencies. At the time it aimed to deliver a UL-certified model of the generator in 2023.

Targeting commercial, industrial, and grid-side customers, the generators can be installed in grid-scale arrays to form systems of 230 kW to tens of megawatts. Their software allows dynamic switching between clean fuels, while the full dispatchability enables the firming of other renewable energy sources like solar and wind.

(USD 1 = EUR 1.009)

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