Life Cycle Assessment and Integrated Sustainability Evaluation of Coal-Sludge Co-firing Power Generation

The co-firing of municipal sewage sludge in coal-fired power plants is considered a potential pathway for waste management and low-carbon transition, yet comprehensive sustainability evaluations under China's dual-carbon goals remain limited. This study fills this gap by quantifying the environmental, economic, and integrated performance of a typical 2×330 MW co-firing plant in northern China using a cradle-to-gate life cycle assessment (LCA), life cycle costing (LCC), and the analytic hierarchy process (AHP). The results show that global warming potential dominates the total environmental impact (82.3%). Co-firing reduces internal costs by 1.1% while slightly increasing external costs by 0.8%. The integrated sustainability score of the co-firing scenario (0.5021) is marginally superior to that of conventional coal power, with all coefficients of variation below 5.5%. The evidence indicates that coal-sludge co-firing represents a viable transitional co-processing solution for sewage sludge, providing quantitative evidence for policy support without a significant net increase in environmental burdens.