Calcium looping for power generation with CO2 capture: The potential of sorbent storage for improved economic performance and flexibility

The aim of this work is to investigate the potential of calcium looping (CaL) CO₂ capture system for power plants with sorbent storage, for flexible and low-emission power generation from coal. Two different CaL systems have been analyzed for CO₂ capture from a reference pulverized coal power plant: (i) a Baseline CaL system and (ii) a FlexiCaL system with sorbent storage. The sorbent storage systems can be exploited in two ways: the primary storage system allows to decouple the carbonator and the calciner load and reduce the size of the calciner island; the secondary storage unit allows to increase/reduce the maximum/minimum power output of the plant for improved grid services. Heat and mass balances have been computed at different loads with process simulation software, considering the off-design operation of the main plant components. A simplified economic analysis has been carried out to compute the cost of electricity and estimate the economic benefits of the primary sorbent storage system for a given power generation profile. The method used in this work allowed to compute the off-design behaviour of the CaL power plant with the highest accuracy among the literature studies and to understand the potential of the secondary solids storage to provide grid services for the first time.