Hybrid Fuels Enhance Sustainability and Economics of Cement Manufacturing

The conventional cement production is characterized by energy-intensive and relies heavily on fossil fuel, resulting in substantial CO2 emissions. Substituting fossil fuels with alternative energy sources is therefore essential for improving process efficiency and reducing the carbon footprint of cement manufacturing. In this study, six representative alternative fuels—including oily sludge, biomass, waste tires were assessed at thermal substitution rates (TSR) of 10%, 20%, 30%, and 40%. A total of 25 combustion scenarios were modeled were to evaluate their effects on clinker production, CO2 emissions, energy efficiency, and techno-economic performance. The simulation results show that alternative fuels can not only effectively reduce coal consumption but also improve energy efficiency. Under the same condition of heat value, in the 10% waste tire A substitution scenario, coal consumption is reduced to 17,325 kg/h, and in the 40% waste tire B substitution scenario, coal consumption is reduced to 11,550 kg/h. The oily sludge-based alternative fuels exhibit the most significant enhancement in cement clinker yield, followed by biomass and waste tire B. Waste tire A is similar to the cement clinker output of conventional cement production. In terms of CO2 emissions, in the 40% oily sludge B substitution scenario, compared with the conventional cement production process, CO2 emissions are reduced by 118,300 tons, relative to the conventional cement production process, representing a 13.17% reduction. In terms of economic performance, a high proportion of oily sludge substitution can reduce the conventional cement production cost by 392.89 CNY/t to 358.45 CNY/t, reduced by 8.77%. Alternative fuels play a crucial role in significantly enhancing energy efficiency and promoting decarbonization. Notably, oily sludge demonstrates optimal techno-economic performance, providing critical parameters for industrial-scale solid waste co-processing.