Integration of Carbon Capture, Utilization and Storage with Molten Salt Thermal Energy Storage and Microalgal Carbon Fixation for Circular Development in the Thermal Power Sector
Under the synergistic policy framework of carbon peaking, carbon neutrality, and the circular economy, existing carbon capture, utilization, and storage (CCUS) projects in coal-fired power plants (CFPPs) face significant challenges, including high regeneration energy demand, reliance on turbine steam extraction, limited carbon utilization pathways, poor economic viability, and difficulties in by-product management. This study proposes an integrated low-carbon retrofitting strategy that couples molten salt thermal energy storage (TES) and microalgal carbon fixation systems with existing CCUS facilities under minimal plant modification. A closed-loop carbon and energy utilization framework is established, integrating waste heat recovery, primary CO2 capture, secondary biological carbon fixation, and biomass fuel recycling. The system operates through a gradient synergistic mechanism: (i) recovered waste heat is stored in a molten-salt TES unit to provide regeneration energy, replacing conventional steam extraction; (ii) CO2 is initially captured by the CCUS process; (iii) residual CO2 is further utilized by microalgae for deep carbon fixation; and (iv) harvested algal sludge is converted into biomass fuel for co-firing within the power plant, completing the carbon recycling loop. The technical architecture, coupling mechanisms, scenario-specific implementation pathways, and operational risk control strategies are systematically evaluated. Results indicate that the integrated system can reduce energy consumption by approximately 30%–40% per unit of CO2 captured, increase overall carbon fixation efficiency by 15%–20%, and shorten the investment payback period to less than five years. The framework enables transformation of conventional coal-fired power plants from single-purpose energy producers into multifunctional circular systems integrating energy generation, carbon cycling, and resource recovery. Owing to technological maturity, adaptability to different plant capacities and geographical conditions, and a clear deployment roadmap, this solution provides a practical, replicable, and scalable pathway for low-carbon and circular transition.