New Batteries That Store Blistering Heat Are Taking Off

Thermal batteries store surplus renewable electricity as heat for industrial use, addressing a problem that conventional batteries do not: factories need enormous, steady supplies of steam and high-temperature heat, usually produced by burning fossil fuels. In South Dakota, Antora Energy uses cheap electricity from wind farms to heat carbon blocks to as much as 4,352 degrees Fahrenheit. The blocks can retain heat for days and supply steam to a nearby ethanol refinery for up to 100 hours. The refinery says the steam costs about as much as natural gas, and plans to largely shut down its gas boilers. The project also takes advantage of wind power that might otherwise be curtailed because transmission lines cannot carry it elsewhere.

Antora and competitors such as Rondo Energy, which heats firebricks, aim to extend the approach to industries including cement, paper and brewing. A laboratory study suggests thermal storage could eventually meet as much as one-third of U.S. industrial heat demand if costs fall, potentially cutting emissions from a major source of climate pollution. But companies must demonstrate that their systems can scale and withstand extreme temperatures, while electricity pricing rules in many regions make it difficult to charge only when renewable power is cheap. Interest is also growing among data-center developers seeking reliable energy, though converting electricity to heat and back into power is inefficient. Energy-market disruptions and large investments, including Antora’s recent $550 million funding round, are helping drive the technology’s expansion.