An experimental characterization of Calcium Looping integrated with concentrated solar power

Abstract

Carbon Capture and Sequestration (CCS) and renewable energy sources are both essential to mitigate the CO2 emissions in the near future. Calcium Looping (CaL) is an important post-combustion carbon capture technology that has reached the maturity of the pilot plant stage. On the other side Concentrated Solar Power (CSP) is a fast-growing renewable technology in which solar energy, concentrated up to several MWm−2, can be used to produce electricity or to drive an endothermic chemical reaction. The integration between a CSP system and a CaL cycle, in order to use a renewable source to supply the energy required by the calciner, would strongly improve the performance of the CaL process by overcoming some of its main drawbacks. However, the role that highly concentrated radiation can have on the sorbent properties in the CaL cycle is still matter of investigation. In this study, the CaL-CSP integrated process is experimentally investigated through the use of a directly irradiated Fluidized Bed (FB) reactor. Simulated concentrated solar radiation featured a peak flux on the FB surface of approximately 3MWm−2 and a total power of about 3kWth. Several calcination and carbonation tests have been performed on samples of a commercial Italian limestone, in order to establish the evolution of the sorbent capacity of CO2 capture at increasing number of cycles. The properties of the limestone samples were further investigated by means of microstructural characterization. The comparison between results obtained with and without the use of the solar concentrated flux to thermally sustain calcination provides useful information on the potential of solar driven CaL and on the measure to overcome some of its potential limitations.