Techno-Economic Analysis of a Solar Hybrid Combined Cycle Power Plant Integrated with a Packed Bed Storage at Gas Turbine Exhaust

The present work performs a techno-economic analysis of an innovative solar-hybrid combined cycle composed of a topping gas turbine coupled to a bottoming packed bed thermal energy storage at the gas turbine exhaust, which runs in parallel to a bottoming steam cycle. Plant performances have been evaluated in terms of the capacity factor, the specific CO2 emissions, the capital expenditure, and the Levelised Cost of Electricity. The influence of the combustion chamber outlet temperature, solar multiple and energy storage capacity has been assessed by means of a sensitivity analysis. The present study also compares the previously listed performance against that of conventional molten salt tower Concentrating Solar Power plants and traditional combined cycle gas turbine power plants with equivalent installed capacities and load factors. The results show that it is worth hybridizing the system, particularly at high combustion chamber outlet temperature, large storage size and solar multiple. Furthermore, plant configurations leading to a Levelised Cost of Electricity lower than 110 $/MWh can be achieved for a capacity factor of about 60%. Under these working conditions, the proposed configuration would be only 1.66 times more costly than an equivalent size CCGT. At the same time, it would yield less than half of the emissions of the latter. Simultaneously, the proposed layout is considerably cheaper than an equivalent molten salt Concentrating Solar Power plant.