Design performance analysis of supercritical CO₂cycle for CSP application with sensible heat thermal storage

Supercritical CO2 (sCO2) cycles can achieve higher efficiencies than steam Rankine cycles at a higher temperature with a compact plant footprint. Concentrated solar power plants are capital intensive, as there is no fuel-related operating cost, the capital cost must be reduced to realise a reduction in the levelised cost of electricity. Power cycle efficiency and the temperature difference between the hot and cold storage tanks are the critical thermodynamic parameters to reduce the size and the cost of solar field and two-tank storage system whilst the power cycle specific power has also to be maximised to lower the power block cost. With these objectives, three potential cycle configurations were selected for detail assessment; a recompression cycle, partial cooling cycle and a partial heating cycle. A set of performance maps are presented using multi-objective optimisation, which maximises the efficiency and the specific power is explored for five different compressor inlet temperature of 35°C, 40°C, 45°C, 50°C, 55°C and two turbine inlet temperatures of 600°C and 700°C. The overnight capital cost across the Pareto front are estimated and the economic performance map is presented, which guides in selecting an optimal design for different boundary conditions.