Mainspring

About Mainspring

Mainspring Energy, founded in 2010 by Stanford engineers Shannon Miller, Matt Svrcek, and Adam Simpson, is a developer of onsite linear power generators. The company originated from research conducted by the co-founders in a thermodynamics laboratory at Stanford University, with Miller's work funded by the Global Climate Energy Project. Miller, who serves as CEO, has a background in thermodynamics and was motivated to address carbon emissions while expanding access to affordable electricity. The company was formerly known as EtaGen.

Mainspring's core product is the Linear Generator, a technology that differs from traditional engines or turbines by directly converting motion in a straight line into electricity. This is achieved through a low-temperature, flameless reaction of air and fuel that drives magnets through copper coils. The design features only two moving parts and an air-bearing system that removes the need for oil, which contributes to lower maintenance costs. A key feature is its fuel flexibility, allowing it to operate on natural gas, biogas, hydrogen, ammonia, and propane, and to switch between them seamlessly. The generators are designed to be modular, scalable from 250 kW units to over 100 MW, and produce near-zero NOx emissions without requiring after-treatment systems.

The company's business model focuses on providing power generation solutions to commercial and industrial customers, data centers, utilities, and microgrids. Mainspring offers an energy-as-a-service model where customers can install the generators with no upfront cost and pay for the energy consumed, often resulting in annual savings. Mainspring serves clients such as Fortune 500 companies, including grocery chains and logistics firms like Lineage Logistics. The company partners with other firms, such as NextEra Energy Resources and Schneider Electric, for financing, deployment, and integration into microgrids. Commercial shipments began in mid-2021 after initial pilot deployments in 2020.

Mainspring has secured significant funding from investors including Bill Gates, Khosla Ventures, Lightrock, and General Catalyst. Total funding has reached over $739 million through multiple rounds. The company is expanding its manufacturing capabilities with a new facility in Allegheny County, Pennsylvania, supported by grants from the U.S. Department of Energy and the state of Pennsylvania.