Thermal battery hits 4,350°F, stores electricity as heat for 100 hours

Researchers at Fourth Power, an MIT spinout led by Professor Asegun Henry, have developed a novel thermal battery that stores electricity as heat in carbon blocks heated to approximately 4,350°F (2,400°C), nearly half the temperature of the Sun’s surface. This system uses molten tin to transfer heat and thermophotovoltaic (TPV) cells to convert the intense light emitted by the white-hot carbon blocks back into electricity with over 40% efficiency—a record for TPV technology. Operating at such high temperatures allows for higher power density, reducing system size and costs compared to conventional energy storage solutions like lithium-ion batteries. The thermal battery offers long-duration energy storage, capable of providing power for 10 to over 100 hours with minimal heat loss (about 1% per day), making it suitable for utilities, renewable energy integration, and data centers. Its modular design enables scaling by adding storage or power modules, with plans to demonstrate a one-megawatt-hour system