Carnot Batteries are an emerging technology for the inexpensive and site-independent storage of electric energy at medium
to large scale. Also referred to as “Pumped Thermal Electricity Storage” (PTES) or “Pumped Heat Storage” (PHES), a Carnot Battery transforms electricity into thermal energy, stores the thermal energy in inexpensive storage media such as water or molten salt and transforms the thermal energy back to electricity as required, see Figure 1.
Reaching from medium to high capacities up to 100MW/1000MWh, Carnot Batteries have the potential to solve the global storage problem of renewable electricity in a more economic and environmentally friendly way than conventional batteries.

Figure 1. Carnot Battery – Basic principle