Sam Atlman-backed Exowatt wants to power AI data centers with billions of hot rocks

Exowatt, backed by Sam Altman and Andreessen Horowitz, aims to revolutionize energy supply for AI data centers by delivering ultra-low-cost, round-the-clock solar power at a target price of one cent per kilowatt-hour. The company’s core technology repackages concentrated solar power (CSP), also known as thermal solar power, which uses sunlight to heat special bricks inside shipping container-sized units called P3 devices. These bricks store thermal energy that can be converted into electricity via Stirling engines, enabling continuous power generation even when the sun isn’t shining. Each thermal battery can retain heat for up to five days, and multiple units can be combined to scale output according to demand. Exowatt has raised an additional $50 million in an extension to its $70 million Series A round, led by MVP Ventures and 8090 Industries, reflecting strong market interest and momentum. The company currently has a backlog of about 10 million P3 units, representing 90 gigawatt-hours of