Mainspring Energy

2024 IEEE Spectrum Emerging Technology Award

Sponsored by IEEE Spectrum

Recognized for its linear generator

In 2004, a mechanical engineering professor at Stanford University asked several of his Ph.D. students: “What is the most efficient and practical way possible to convert chemical-bond energy into useful work?” That question triggered an engineering project that resulted in the formation, in 2010, of Mainspring Energy by three of those Ph.D. students. The Menlo Park, Calif., company is now producing a machine that generates 230 kilowatts using almost any fuel, including ammonia, hydrogen, biogas, and natural gas. Mainspring calls its machine a linear generator because it converts linear motion into electricity. Fuel and air compressed in the center of a linear assembly react and push outward, driving a set of magnets on each side of the reaction chamber through conducting copper coils, generating electricity. Compressed-air springs at either end of the assembly halt and reverse the outward motion of the magnets and ready the machine for the next expansion-compression cycle. The entire process is controlled with very high precision to maximize efficiency. The machines occupy roughly the same area as a parking space and are already generating electricity at grocery stores, shopping centers, and scores of other businesses. The company’s backers include some of the biggest names in tech investing, including Bill Gates and Vinod Khosla.