Life Cycle Assessment Analysis and Comparison of 1000 MW S-CO₂ Coal Fired Power Plant and 1000 MW USC Water-Steam Coal-Fired Power Plant

The objective of this paper is to understand the benefits that one can achieve for large-scale supercritical CO₂ (S-CO₂) coal-fired power plants. The aspects of energy environment and economy of 1000 MW S-CO₂ coal-fired power generation system and 1000 MW ultra-supercritical (USC) water-steam Rankine cycle coal-fired power generation system are analyzed and compared at the similar main vapor parameters, by adopting the neural network genetic algorithm and life cycle assessment (LCA) methodology. Multi-objective optimization of the 1000 MW S-CO₂ coal-fired power generation system is further carried out. The power generation efficiency, environmental impact load, and investment recovery period are adopted as the objective functions. The main vapor parameters of temperature and pressure are set as the decision variables. The results are concluded as follows. First, the total energy consumption of the S-CO₂ coal-fired power generation system is 10.48 MJ/kWh and the energy payback ratio is 34.37%. The performance is superior to the USC coal-fired power generation system. Second, the resource depletion index of the S-CO₂ coal-fired power generation system is 4.38 µPR_china,90, which is lower than that of the USC coal-fired power generation system, and the resource consumption is less. Third, the environmental impact load of the S-CO₂ coal-fired power generation system is 0.742 mPE_china,90, which is less than that of the USC coal-fired power generation system, 0.783 mPE_china,90. Among all environmental impact types, human toxicity potential HTP and global warming potential GWP account for the most environmental impact. Finally, the investment cost of the S-CO₂ coal-fired power generation system is generally less than that of the USC coal-fired power generation system because the cost of the S-CO₂ turbine is only half of the cost of the steam turbine. The optimal turbine inlet temperature T₅ becomes smaller, and the optimal turbine inlet pressure is unchanged at 622.082°C/30 MPa.