Multi-criteria thermodynamic analysis of pumped-thermal electricity storage with thermal integration and application in electric peak shaving of coal-fired power plant

• A heat pump – organic Rankine cycle (HP-ORC) based storage system integrated with waste heat is investigated. • Based on the results of multi-objective optimization, the roundtrip and exergy efficiencies can reach 0.97 and 0.64. • Exemplary combination of ORC based PTES with a coal-fired power plant for peak shaving is introduced. • The maximum peak shaving capacity of a 300 MW coal-fired power plant coupled with Carnot battery can reach 94.4%. The development of efficient energy storage systems to compensate for the intermittency of renewable energy sources has become a key step in the widespread use of renewable energies. Pumped-thermal electricity storage, which has drawn wide attention in recent years, has the advantages of being unlimited by geographical conditions, high energy storage density and low costs. In this paper, a heat pump – organic Rankine cycle (HP-ORC) based storage system integrated with waste heat has been developed and analyzed to find the suitable operation parameters for the existing coal-fired power plant. The systematic exergy loss is calculated and the trade-off optimization between roundtrip efficiency and exergy efficiency is also performed to find the Pareto Front. It is concluded that the exergy losses of the sensible and latent heat stores account for 35% and 31% of the total exergy loss, respectively; when the heat source temperature is 110 °C, the roundtrip efficiency can reach 1.26. Furthermore, the two-objective optimization results show that when heat source temperature and maximum storage pressure are designed to be 87.1 °C and 3.6 MPa, roundtrip efficiency and exergy efficiency can reach 0.97 and 0.64, respectively. Under the optimization results, the maximum peak shaving capacity of the coal-fired power plant integrating Carnot battery can reach 94.4%.