Thermo-economic assessment and optimization of thermally integrated pumped thermal energy storage with vapor-extraction regeneration

Thermally integrated pumped thermal energy storage (TIPTES), as a flexible, low-cost, and efficient energy storage system, significantly boosts the proportion of renewable energy on the energy supply side and effectively balances the mismatch between energy supply and demand. Based on basic regenerative TIPTES (BR-TIPTES), a novel vapor-extraction regeneration TIPTES system is developed, which is divided into: single-stage vaporextraction regeneration type (SR-TIPTES) and double-stage vapor-extraction regeneration type (DR-TIPTES). Taking round-trip efficiency, exergy efficiency, and levelized cost of storage (LCOS) as the objective functions, both single-objective and multi-objective optimizations are performed via improved cuckoo search algorithm (CSA) and the second generation multi-constraint non dominated cuckoo search algorithm (NSCSA-II), respectively. Single-objective optimization results demonstrate that DR-TIPTES system achieves a 9.3 % increasement in round-trip efficiency, a 15.6 % enhancement in exergy efficiency and a 9 % reduction in LCOS, distinguishing itself from the other regeneration systems. For multi-objective optimization, a round-trip efficiency of up to 60.35 % and a lowest LCOS of 0.3576 $/kWh with implementation of DR-TIPTES demonstrate the most significant thermo-economic performance improvement. Economic analysis and exergy destruction analysis are conducted. Among all the system configurations being considered, turbine and compressor stand out as occupying a prominent position in terms of investment share, primarily attributed to their significantly higher output and input power requirements. Condenser and evaporator contribute the highest exergy destruction, primarily due to the largest disparities in enthalpy and entropy between inlet and outlet.