Thermo-economic analysis of individually coupled steam, heating, and cooling production in a Carnot battery

Pumped thermal energy storage (PTES), a subtype of Carnot battery, is considered one of the approaches to address industrial decarbonization due to its high efficiency and synergistic waste heat integration. Due to its thermal energy storage mechanism, PTES has multi-energy supply capabilities. However, PTES is predominantly treated as a subsystem in current research, leaving its operational flexibility underexploited. Moreover, the limited research in the field of multi-energy PTES (ME-PTES) has yet to address system optimization across multiple energy types and varying system scales. In this study, models of ME-PTES separately supplying high-temperature steam (HTS), medium-temperature hot water (MTW), and low-temperature cold water (LTW) are established. A two-level performance-capacity optimization method is proposed to evaluate the thermo-economic performance of these systems under varying energy demands. A comparative study of four PTES configurations was conducted using thermodynamic and economic metrics. The research results indicate that multi-energy supply effectively enhances the energy efficiency of PTES while exhibiting only marginal changes in total product unit cost. The optimal total product unit cost for HTS-PTES, MTW-PTES, and LTW-PTES are 0.17 $/kWh, 0.17 $/kWh, and 0.18 $/kWh, respectively, with corresponding energy efficiency of 1.00, 1.57, and 0.78. Compared to E-PTES, the economic metric changed by −2.0%, −0.6%, and 11.5%, while energy efficiency increased by 59.7%, 149.7%, and 24.4%.