Thermodynamic analysis of solar thermochemical CO2 capture via carbonation/calcination cycle with heat recovery

Thermodynamic analysis of an ideal solar-driven cycle for the capture of carbon dioxide using a CaO-based carbonation/calcination cycle is performed for gas mixtures with compositions corresponding to those of atmospheric air and power plant flue gases. Solar energy input requirements are examined as a function of CO2 molar fraction in the input gas, gas phase heat recovery, solid phase heat recovery, and carbonation and calcination temperatures. Gas phase heat recovery can reduce the solar energy input requirements by 22–99%, with the largest gains occurring at lower CO2 molar fractions. Solid phase heat recovery can reduce the solar energy input requirements by 0.1–26%, with the largest gains occurring at higher CO2 molar fractions. For a carbonation temperature of 673 K and a calcination temperature of 1273 K, over 45 MJ per mol of CO2 captured is required for a CO2 concentration of 300 ppm with no heat recovery. The minimum solar energy input required with perfect gas and solid heat recovery is 207 kJ per mol of CO2 captured.

► Solar energy input requirements decrease with increasing CO2 concentration in the input gas.
► Gas phase heat recovery can reduce solar energy input requirements by max. 99%.
► Solid phase heat recovery can reduce solar energy input requirements by max. 26%.
► Effect of increasing either reaction temperature depends on heat recovery effectiveness.