Thermal economy analysis and multi-objective optimization of a small CO2 transcritical pumped thermal electricity storage system

Abstract

With expansion of application scale of distributed renewable energy, importance of researching small electricity storage system is increasing. Thermal economic performance of a small CO2 transcritical pumped thermal electricity storage system (SCT-PTES) is studied in this paper. NSGA-II optimization method and TOPSIS decision method are used to optimize system performance. This paper also proposes a small CO2 transcritical pumped thermal electricity storage coupled building heating system (STC-PTES-H) scheme. The system performance is also studied. Results show that: (a) When round-trip efficiency and LCOS of SCT-PTES are 26.93% and 0.3862 $/(kW·h), respectively, thermal economic performance is optimal. (b) When amount of electricity produced by renewable energy sources is 10 MW, LCOS of SCT-PTES is 0.2002$/(kW·h). (c) Correlation between thermodynamic performance and economic performance of system is fitted, and optimization time is reduced. It provides a theoretical basis for optimization of thermal economic performance of system. (d) Energy utilization of SCT-PTES-H can reach 97.66%. It makes better use of energy. This research provides technical support for application of SCT-PTES in distributed renewable energy power plants.