Life cycle environmental impact assessment of fuel mix-based biomass co-firing plants with CO₂ capture and storage

As a carbon-neutral renewable energy source, biomass co-firing with coal contributes to reducing the carbon intensity of pulverized coal power plants with CO₂ capture and storage; thus, this process significantly reduces the greenhouse gas emissions of the power industry. However, various types of environmental impacts caused by co-firing have hindered the large-scale deployment of this technology. In this study, ten life cycle assessment models were developed based on the Integrated Environmental Control Model and GaBi software to quantify the performance parameters of different power plants and the influence of the co-firing ratio on various environmental impact categories. The system boundaries included raw material acquisition, raw material transport, energy conversion of power plants, CCS and brine treatment. The results indicated that a pulverized biomass/coal co-firing power plant with CCS can achieve near-zero emissions at a co-firing ratio of 25% and negative emissions of 877 kg CO₂-e/MWh from a life-cycle perspective when coal is totally replaced. Co-firing biomass and coal in power plants has a passive impact on seven environmental categories, such as the eutrophication potential and toxicity potential, rather than on the global warming potential, abiotic resource depletion potential and acidification potential. The major causes of environmental burden shifting are energy penalties and indirect emissions from high-energy-consumption processes, especially emissions of N₂O, NH₃ and ethylene oxide released during biomass extraction and solvent preparation. The conclusions and recommendations presented in this paper may have implications for deep decarbonization in other industrial sectors.