US-based, on-site power generation technology developer Mainspring Energy received $95m on Tuesday in a series D round featuring energy utility American Electric Power (AEP) and oil and gas producers Chevron and Equinor.
The round was led by Devonshire Investors, a private equity firm affiliated with financial services and investment group Fidelity, and included Princeville Capital, 40 North Ventures, Khosla Ventures, ClearSky, KCK Group and private investor Bill Gates.
Chevron was represented in the round by its corporate venturing unit, Chevron Technology Ventures, and it boosted the company’s funding to $228m since it was founded in 2010 as EtaGen.
Mainspring has developed a linear generator which can run on multiple types of fuels such as biogas and hydrogen. Its technology is based on research conducted at Stanford University and uses low-temperature chemical reactions to move oscillators through copper coils to produce electricity.
The company claims its generators produce almost no emissions of nitrogen oxide, a pollutant typically associated with the burning of fossil fuels.
The funding comes after Mainspring closed an $83m series C round in 2018 backed by AEP as well as Equinor’s corporate venturing arm (then known as Statoil Energy Ventures) and Centrica Innovations, a corporate venturing subsidiary of energy utility Centrica.
KCK Group, Khosla Ventures, Louis M Bacon and Bill Gates made up the participants in the series C round. The company has not revealed details of earlier funding but described Gates and Khosla Ventures as existing investors in the 2018 round.