Pumped Thermal Energy Storage Based on High Temperature Steam Cycles

Pumped thermal energy storage (PTES) is a thermo mechanical storage concept in which a heat pump cycle is used to charge a thermal storage, which delivers heat to operate a power cycle during discharge. The first pumped thermal energy storage concepts were based on steam cycles combined with steam accumulators. More recent configurations apply combinations of latent heat storage and sensible heat storage to increase efficiency. This chapter present the thermodynamics of current PTES concepts based on Rankine cycles, an overview of various PTES systems based on Rankine cycles is provided. These variants differ in complexity and maturity, for some of these variants the integration of low temperature waste heat during the charging process is an option. The relevance of the efficiencies of key components for the roundtrip efficiency and for the required specific capacities of engines and storages is shown. An outlook on the advancement of PTES concepts based on Rankine cycle by the development of components adapted to the specific boundary conditions is presented.