Modeling and performance analysis of subcritical and supercritical coal-fired power plants with biomass co-firing and CO₂ capture

Coal-fired power plants are the largest source of carbon dioxide (CO₂) emissions into the atmosphere, and these emissions can be effectively reduced by improving the efficiency of the plants, co-firing sustainably grown biomass and applying carbon capture and storage technologies. In this study, the energy and environmental performances of both subcritical (SubC) and supercritical (SC) pulverized coal-fired power plants with biomass co-firing and integrated with an advanced amine-based postcombustion CO₂ capture system were evaluated and compared. The impact of biomass (hybrid poplar) addition was investigated at different co-firing ratios varying up to 30% on a heat input basis. All plant configurations were modeled and simulated with Aspen Plus process simulation software. The results show that the use of a SC steam cycle has a positive impact on the energy and environmental performance of the investigated plants, improving the efficiency by 2.4% points and reducing the total fuel consumption and CO₂ emissions by 6% in comparison to those of the SubC cases. Biomass co-firing has a negative impact on the energy performance of plants while significantly reducing fossil-based carbon emissions. The reduction of net CO₂ emissions is almost proportional to the biomass percentage in the feed. At 30% biomass co-firing, the net plant efficiency is reduced by approx. 1% point, while the net CO₂ emissions are 28% lower than those in coal-fired only plants. The introduction of CO₂ capture has a major impact both on the emissions generated and on the energy efficiency. Depending on the plant type and co-firing ratio used, the net plant efficiencies are 8.7–9.3% points lower than those of non-capture cases. The net CO₂ emissions achieve negative values when carbon is captured from the biomass co-firing plants.