Thermally integrated pumped thermal energy storage systems based on organic Rankine cycle: Comparative investigation and multi-objective multiverse optimization

This work introduces two new thermally integrated pumped thermal energy storage (TIPTES) systems, including thermally integrated vapor compression heat pump (TIHP) as a charging cycle and dual-pressure organic Rankine cycle (DPORC) and dual-loop organic Rankine cycle (DLORC) as discharging cycles to investigate their capability of improving roundtrip efficiency compared with the basic ORC (BORC). The thermodynamic and economic performance of the proposed TIHP-DPORC and TIHP-DLORC are analyzed and compared with TIHP-BORC using various working fluids. The multi-objective multiverse optimization algorithm is conducted to ascertain the systems' optimum roundtrip efficiency and cost rate. Results indicate that at the same storage temperature, the TIHP-DLORC gives the highest roundtrip and exergy efficiencies of 219.9% and 43.53% with R1233zd(E), indicating 6.69% and 8.04% improvements compared with the optimum TIHP-BORC. Moreover, it shows the lowest levelized cost of storage (LCOS) and payback period (PP) of 0.160 $/kWh and 4.5 years, respectively, with a maximum net present value of 1.973 M$. Although the cost rate of TIHP-DLORC is high, its excellent thermodynamic and economic performance compared with the existing TIPTES systems in the literature indicates that DLORC is a more appropriate candidate to be applied in the TIPTES systems.