110th anniversary: Calcium looping coupled with concentrated solar power for carbon capture and thermochemical energy storage

Concentrating solar power (CSP) technologies with energy storage can greatly enhance the dispatchability and the exploitation of solar energy in different applications. In this context, the present study addresses coupling CSP with calcium looping (CaL) along the 2-fold perspective of accomplishing: (a) carbon capture and sequestration or utilization (CCSU); (b) thermochemical energy storage (TCES). The experimental campaign, aimed at assessing limestone performances over extended cycling under realistic operating conditions, was performed in a fluidized bed reactor directly irradiated by a simulator of concentrated solar radiation. Infrared thermography was used to map the fluidized bed surface during "solar-driven" calcination. Experimental results indicated that TCES operating conditions yield a more reactive material due to the development of better microstructural properties, as inferred from N2- and Hg-intrusion porosimetry, which reflect the different thermal history experienced by sorbent material. Working out of process variables in terms of density of energy storage revealed that the CSP-CaL integrated process can represent an attractive alternative option to commercial technologies based on molten salts.