Carnot Battery

A Carnot battery is a type of energy storage system that stores electricity as thermal energy: during charging, electricity is converted into heat and kept in a heat store, and during discharge, that stored heat is converted back into electricity, an approach also called power-to-heat-to-power. The underlying concept dates back roughly a century to a patent by Fritz Marguerre, though interest in it has revived recently alongside the growth of renewable electricity, and the researcher Andre Thess coined the specific term Carnot battery in 2018 ahead of the first International Workshop on Carnot Batteries. The name draws on Carnot theorem, which sets the maximum possible efficiency for converting heat into mechanical energy, since a Carnot battery round-trip discharge efficiency is bounded by that same Carnot efficiency limit; the category as defined encompasses related approaches such as pumped thermal energy storage and liquid air energy storage.