Comparison and optimization of operating conditions in power generation integrated with thermal energy storage systems

Thermal energy storage (TES) systems are crucial for mitigating renewable energy variability and ensuring a stable power supply. This study evaluates the efficiency of various power-generation cycles, including the Brayton and Rankine cycles, to optimize their integration with TES systems. Thermodynamic efficiency equations and the CoolProp database were used for cycle calculations, and response surface methodology (RSM) was applied to maximize the efficiency. The maximum efficiency of a 30 kW-class micro gas turbine was predicted to be 20.3 % with a 400 kW heat input from TES, whereas a Rankine cycle-based steam turbine operating at < 500 K showed a 7.24 % efficiency. The integration of TES with the Brayton cycle enables higher efficiencies at elevated inlet temperatures but is constrained by the TES maximum operating temperature. Conversely, the Rankine cycle provides stable operation at lower temperatures despite its relatively low efficiency. This study highlights the advantages and limitations of integrating TES with different cycles, providing strategies to maximize renewable energy utilization and enhance energy system flexibility. • Comparison of Brayton and Rankine cycles integrated with thermal energy storage (TES) to address renewable energy variability. • Thermodynamic efficiency equations and CoolProp database utilized to calculate cycle performance and validate with commercial micro gas turbines and steam turbines. • Response surface methodology (RSM) applied to identify optimal operating conditions for 30 kW-class power-generation cycles under varying heat inputs. • Brayton cycle (micro gas turbine) achieved up to 20.3 % efficiency at ∼400 kW TES heat input, while the Rankine cycle (steam turbine) stably operated at < 500 K albeit at lower efficiency (∼7.24 %). • Findings provide integration strategies for maximizing renewable energy utilization through temperature-tailored TES design and optimal operating parameters of power-generation cycles.