How Mainspring Energy Turns Fuel Into Power Without Combustion

Shannon Miller is Co-founder and President of Mainspring Energy, a company developing a new category of power generation technology called the linear generator. Mainspring’s systems generate electricity through a low-temperature, flameless chemical reaction that converts fuel directly into electrical power. Shannon has been at this for about 15 years. She started the company on technology she developed while earning her PhD in mechanical engineering at Stanford, and took it from a lab experiment through commercial deployment to hundreds of megawatts in development and running in the field. Mainspring closed a $258 million Series F in 2025, led by General Catalyst and has raised more than $800 million to date. In this episode of Inevitable, Shannon explains how Mainspring’s technology differs from traditional gas turbines and fuel cells, why modular and fuel-flexible generation is becoming increasingly valuable, and how the growth of data centers is reshaping energy infrastructure. The conversation explores the urgent demand for faster power deployment, the advantages of dispatchable generation, the role of hydrogen and other future fuels, and why flexibility may become one of the most important characteristics of the future electric grid.  Episode recorded on June 2, 2026 (Published on July 7, 2026).  In this episode, we cover:  (0:00) An overview of Mainspring Energy  (1:47) What a linear generator is and how it differs from traditional ones (3:57) Behind-the-meter power and the race for faster time-to-power  (5:47) How Mainspring converts fuel into electricity  (8:18) The benefits of modular power generation  (10:34) Comparing linear generators to fuel cells  (12:32) Where Mainspring fits into modern data center energy stacks  (13:48) Transitioning from prime power to dispatchable grid support  (14:42) Why fuel flexibility matters  (15:27) Use cases for propane and hydrogen switching  (18:57) The economics of power generation and cost competitiveness  (20:44) Scaling from laboratory technology to commercial deployment  (22:49) How utilities evaluate new generation technologies  (25:00) Shannon’s vision for the future power mix Enjoyed this episode? Please leave us a review! Share feedback or suggest future topics and guests at [email protected] with MCJ:Cody Simms on LinkedInVisit mcj.vcSubscribe to the MCJ Newsletter*Editing and post-production work for this episode was provided by The Podcast Consultant