Techno-Economic Assessment of Fluidized Bed Calcium Looping for Thermochemical Energy Storage with CO2 Capture

Abstract

The multicyclic carbonation-calcination of CaCO3 in fluidized bed reactors is a promising process for both thermochemical energy storage (TCES) and CO2 capture. In this paper, a techno-economic assessment of the calcium loop (CaL) process with simultaneous TCES and CO2 capture from an existing CO2-emitting facility is carried out. Inputs to the process are non-dispatchable high temperature heat and a stream of flue gas, while the process outputs are electricity (both dispatchable and non-dispatchable) and CO2 for compression and storage. The process is sized so the charging section can run steadily during 12h per day and the discharging section to operate steadily 24h per day. The study assesses the economic performance of the process through the breakeven electricity price (BESP) and cost per CO2 captured. The study excludes the costs of the renewable energy plant and the CO2 transport and storage. The sensitivity of the results to the main process and economic parameters is also assessed. Results show that the BESP of the case with the most realistic set of economic predictions ranges between 141 and -20 $/MWh for varying plant size. When assessed as a carbon capture facility with a revenue made from both the electricity sale and the carbon capture services, the cost ranges between 178 and 4 $/tCO2-captured. The investment cost of the reactors is found to be the largest fraction of the computed costs, while the sensitivity analysis points at the degree of conversion in the carbonator as the most crucial parameter, with large cost reductions for increased conversion.