Mainspring Energy Inc. has announced the successful closure of a $258 million Series F financing round, aimed at scaling the company’s linear generator power business and expanding its operations in both manufacturing and customer sales. The company also welcomes two new board members, Tom Linebarger, former Chairman and CEO of Cummins, and Bethany Mayer, former CEO of Ixia, who bring extensive experience in the energy and technology sectors.
The financing round was led by General Catalyst, a global investment and transformation firm, with additional participation from Amazon’s Climate Pledge Fund, DCVC, Temasek, Marunouchi Innovation Partners, M&G Investments, Pictet Group, as well as earlier investors such as Lightrock, LGT Bank, Khosla Ventures, and Gates Frontier.
Mainspring’s Linear Generators offer a unique combination of cost-efficiency, reliability, and flexibility, capable of switching fuels dynamically. These generators are fully dispatchable, feature low emissions, and can be easily permitted for installation anywhere. Their scalability, from single units to grid-level arrays delivering 250 kW to over 100 MW, makes them adaptable to varying energy demands, allowing Mainspring to meet the power needs of diverse sectors like data centers, EV charging stations, commercial buildings, residential developments, and hospitals.
In a statement, Linebarger expressed his enthusiasm about joining Mainspring’s Board at this pivotal moment for the energy sector. “The demand for innovative power solutions has never been more pressing, and Mainspring offers a unique solution to meet these needs.”
Thomas Selby, corporate development manager at Amazon’s Climate Pledge Fund, highlighted Mainspring’s potential to drive low-carbon energy solutions and strengthen the electric grid, which aligns with Amazon’s goal of achieving net-zero carbon emissions by 2040. He expressed excitement about partnering with Mainspring to support the company’s efforts in scaling its operations.
The addition of Linebarger and Mayer to Mainspring’s Board brings invaluable expertise. Linebarger, who joins on behalf of General Catalyst, previously led Cummins Inc. and has held key positions at GE Capital and the U.S.-China Business Council. Mayer, a seasoned executive, has held leadership roles at companies such as Sempra, Box, HP, Cisco, and Apple.
Mainspring’s CEO and Founder, Shannon Miller, expressed gratitude for the backing from leading global energy investors and emphasized the company’s readiness to scale rapidly. “This funding, alongside the growth of our Board, will enable us to deliver power faster and at scale, while advancing U.S. leadership in innovative energy technology and enhancing national energy security,” said Miller.