The share of volatile renewable energy sources on the electrical energy production is increasing. In order to bridge supply and demand energy storages become more important. A Pumped Heat Electricity Storage (PHES) system consists of a heat pump, a thermal energy storage and a heat engine. In times of excess supply of electric energy the heat pump is used to charge the thermal energy storage. Later, when the demand exceeds the supply, the thermal energy storage is discharged in order to run the heat engine.
In the thermodynamic limiting case – all processes are reversible – the amounts of received and released electrical energy are equal. Based on energetic, exergetic and economic analyses PHES systems are developed, which are location-independent alternatives to pumped storage plants or compressed air storages.