Within the last 25 years the share of renewable energy sources in electrical energy production in Germany has been rising considerably. The volatility of renewable energy sources results in an increasing mismatch between supply and demand of electrical energy creating the need for storage capacities. The storage of electrical energy via the detour of thermal energy can be realized by a relatively new technology known as Pumped Heat Electricity Storage systems. This paper examines the exergoeconomic performance of such a storage system. A sample system comprising a concrete thermal energy storage is introduced; unsteady operations are simulated and analyzed. Although the achieved efficiencies are reasonable economical operations of the analyzed Pumped Heat Electricity Storage System are currently not possible. For the analyzed operation scenario the exergetic system efficiency, electrical energy output to electrical energy input, amounts to 27.3 %. Considering the storage capacity and the lack of geological requirements the Pumped Heat Electricity Storage system can compete with pumped hydrostorage and compressed air energy storage. However, prices of the order of 60 ct/(kWh) are not competitive considering current energy prices. Based on improved system designs as well as rising energy prices we assess Pumped Heat Electricity Storage Systems as a potential alternative to established storage technologies.
Thermodynamics; Exergy; Pumped Heat Electricity Storage System; PHES; Concrete / Solid Media Thermal Energy Storage