Techno-economic assessment of a low-carbon solar-assisted compressed air energy storage system integrated with calcium looping carbon capture

A solar-assisted compressed air energy storage (CAES) system integrated with calcium looping carbon capture is designed and analyzed to balance grid electricity powered by mainly fluctuating renewable energy sources. The combination of CAES systems with calcium looping carbon capture as a low-carbon grid balancing technology has not been studied before. The approach involved a component-level thermodynamic model, a techno-economic assessment, and a sensitivity analysis, followed by a multi-objective optimization to identify the optimal operating conditions. San Francisco, USA, is considered a geographical case study, with real data on solar availability and hour-by-hour electricity market prices. Assuming a two-hour charging period and a four-hour discharging period, the CAES system stores 177 MWh of electricity during peak production and generates 444 MWh during peak demand. During sunny hours, a heliostat field with a 272 MW capacity supports the grid with a 239 MWh electricity supply and meets the calciner’s thermal energy demand to capture 144 tonCO2/day with a thermal energy penalty of 0.2 MWh/tonCO2. Assuming an average solar radiation of 800 W/m2, the daily round-trip efficiency for the entire storage system is 40 %. Using real data for solar radiation and electricity market prices in San Francisco, the payback period is 4.8 years, and the system in this region prevents the emission of 70 kton CO2 annually.