Fourth Power

Fourth Power is a developer of utility-scale thermal energy storage technology that makes renewable energy an on-demand power source. The company technology transforms domestic energy resources into reliable, on-demand power through thermal storage using inexpensive carbon blocks heated to record-breaking temperatures and liquid tin for heat transfer. The system stores electricity at costs ten times cheaper than lithium-ion, delivering power at costs lower than new natural gas. The modular system provides 5 hours of energy storage scalable up to 100 hours, with thermophotovoltaic power sticks that can be moved in and out of light for flexible grid response. Key features include low cost using abundant domestic materials from petroleum refining by-products, flexibility with independently scalable energy and power, power density with a 100MW 10-hour system fitting within 1 acre, safety through inert argon environment preventing oxidation and fire risk, scalability using domestic supply chains, and a lifespan exceeding 30 years using graphite and tin materials that do not corrode. The heater operates at almost half the temperature of the sun. Founded in 2021 and headquartered in Cambridge, United States, Fourth Power has raised approximately 39 million at the Series A stage with investors including DCVC, Breakthrough Energy, BVCC, and Munich Re. The company was named a 2024 World Economic Forum Technology Pioneer and won Fast Company 2024 World Changing Ideas Awards.