OPTIMUM COUPLING OF THERMAL ENERGY STORAGE AND POWER CYCLES

The present work proposes a methodology that enables decision-making in selecting the adequate power cycle and Thermal Energy Storage (TES) type for a wide range of operating temperatures between 380 and 1200 degrees C. A broad spectrum of power block configurations has been explored including steam Rankine, gas turbine, supercritical CO2, (sCO(2)) combined gas turbine with Rankine, and combined gas turbine with sCO2. The study also evaluated molten salt, particle, and air packed bed TES to identify the most cost-effective power cycle and TES combination. A techno-economic optimization has been conducted aimed at minimizing the Levelized Cost of Storage (LCOS) for different plant capacities and charging costs. Results show that coupling of a sCO(2) power block with recompression and intercooling with a particle TES is the most cost-effective solution for a 100 MWe plant with 12 hours of storage and a charging cost of 50 EUR/MWh. This achieved an LCOS value of 154.7 EUR/MWh at 750 degrees C with a 200 degrees C temperature difference. Particle-based energy storage is the most cost-effective option for a wide range of temperature combinations, while an intercooled sCO(2) power block with an air-packed bed TES should be preferred when electricity is free, and storage represents a significant portion of the capital cost. Molten salt TES is the optimal choice provided that the design temperatures align with the limitations of the salts.