Mainspring Energy

Mainspring Energy, formerly known as EtaGen, is a developer of a new generator technology that use fuels like biogas and hydrogen.

Mainspring Energy is engineering advanced technology to revolutionize the way electricity is generated and delivered.

Mainspring Energy was founded in 2010 by Shannon Miller, Matt Svrcek, and Adam Simpson. The company is headquartered in Menlo Park, California.


Mainspring is delivering a breakthrough new category of power generation — the linear generator — to leading commercial, industrial, and utility customers, to increase their energy resilience, generate cost savings, and meet their sustainability and climate goals.


Mainspring has signed an agreement with Lineage Logistics, a temperature-controlled industrial REIT, and logistics solutions provider, to deploy up to 150 linear generators across its network of distribution facilities in the United States.


Mainspring serves a wide range of customers, including Fortune 500 companies like Kroger and Lineage Logistics, as well as utilities like PG&E, Florida Power and Light, and others.


Mainspring is backed by Bill Gates, Lightrock, NextEra Energy Resources, Khosla Ventures, Fine Structure Ventures, Equinor, American Electric Power, Lineage Ventures, Devonshire Investors, Princeville Capital, and others. The company raised $150M in Series E round on May 24, 2022. This brings Mainspring's total funding to $378M to date.



  • Year founded: 2010
  • Funding Info: $378M over 5 Rounds (Latest Funding Type: Series E)
  • Yearly Revenue: NA
  • Employee Size: 201-500
  • Business Valuation: NA
  • City/Town: Menlo Park
  • State: California
  • Country: United States
Related businesses