Integration of calcium looping and calcium hydroxide thermochemical systems for energy storage and power production in concentrating solar power plants.

Energy storage is a key factor in the development of renewables-based electrical power systems. In recent years, the thermochemical energy storage system based on calcium-looping has emerged as an alternative to molten salts for energy storage in high-temperature concentrated solar power plants. This technology still presents some challenges that could be solved by integrating the thermochemical energy storage system based on calcium hydroxide. This work studies a novel concentrated solar power system integrating calcium-looping and calcium hydroxide thermochemical energy storage systems. The results show that the combined use of hydration-dehydration cycles in the calcination-carbonation processes of the calcium looping for energy storage could partially solve the issue related to the multicyclic deactivation of calcium oxide. The improvement in the conversion of calcium oxide during carbonation is demonstrated experimentally when hydration-dehydration cycles are combined. Numerical simulations demonstrate the technical feasibility of the integrated process, with efficiencies ranging between 38-46%, improved with the increase in calcium oxide conversion in the carbonator, showing the potential of the proposed integration. • Novel integration of thermo-chemical energy storage systems based on CaO. • High temperature calcium looping as main high-efficiency energy storage system. • Medium temperature calcium hydroxide integrated as secondary energy storage system. • Dehydration-hydration processes enhance CaO multicyclic activity in carbonation. • Combined joint operation with roundtrip efficiencies exceed 45%. [ABSTRACT FROM AUTHOR]