Thermal storage as an alternative to electrochemical batteriesAnother alternative is thermal energy storage, in which energy is stored in the form of heat. Due to the high energy density, abundance and low cost of storage materials, thermal storage seems promising for longer-duration storage. Thermal storage implemented in this way has remained marginal because the turbines used in CSP become more efficient as they become larger. Even though smaller CSP plants with integrated thermal storage exist, such as the linear Fresnel plant at Llo in southern France, they remain even more uncommon. It is therefore similar to a lithium-ion battery, but it operates through successive energy conversions from “electricity to heat to electricity” instead of from “electricity to chemical energy to electricity.”