Heat pump-driven adsorption CO₂ capture for simple and cost-effective retrofits of coal power plants

Coal-fired power plants emit almost a third of fossil CO₂ emissions worldwide, and continued operation of existing plants will consume the entire remaining CO₂ budget for 1.5 °C of global warming. Hence, there is an urgent need to rapidly cut emissions from existing power plants. The continuous swing adsorption reactor (CSAR) concept offers a promising solution to this challenge. CSAR uses electrically powered heat and vacuum pumps to drive the CO₂ capture process and does not require the extraction of large amounts of steam from the power plant, greatly simplifying the retrofit process. A bottom-up techno-economic assessment of CSAR compared to conventional temperature swing adsorption (TSA) using the same sorbent showed near-identical performance in terms of energy penalty (8.0 for CSAR and 8.2 %-points for TSA) and CO₂ avoidance cost (54.1 €/ton for CSAR and 55.4 €/ton for TSA). Hence, retrofitting simplicity is achieved at no extra cost. The assessment also showed that, although new coal-fired power plants are economically unviable in regions with already high CO₂ prices, already depreciated plants will be difficult to displace via market forces. For example, the levelized cost of electricity for a coal power plant retrofitted with CSAR drops from 99.2 €/MWh to 68.2 €/MWh when the power plant is already depreciated. When CO₂ prices rise, the optimal strategy involves retrofitting plants located close to CO₂ storage or utilization opportunities for continued baseload operation, while unabated plants without easy access to storage are used at lower capacity factors to integrate rising shares of variable renewables. Simplified retrofitting via CSAR can facilitate the practical and economical execution of this strategy, achieving rapid decarbonization while minimizing the need for new capital investments and disruptive early asset retirements.