Zero/negative carbon emission coal and biomass staged co-gasification power generation system via biomass heating

Abstract

Currently, most coal utilization technologies cannot completely remove CO2, which hinders coal utilization in the context of carbon neutrality. Staged coal-steam gasification has proven to be a potential clean coal utilization method suitable for power generation. However, it cannot achieve zero or negative carbon emissions, and there is the potential to improve energy efficiency further. This study introduces biomass into staged coal gasification and proposes a novel power generation system based on coal- and biomass-staged co-gasification via biomass external combustion heating. Biomass with a lower energy level was combusted to provide heat for gasification, thus improving the energy level matching between the gasification and biomass combustion reactions. The synergistic effect of coal and biomass reduces the tar yield and improves the gasification efficiency. Furthermore, as a carbon-neutral fuel, the introduction of biomass in the staged coal-gasification process can achieve zero or negative carbon utilization of coal. The entire system was simulated using the ASPEN PLUS software, key processes were experimentally validated, and the energy efficiency and carbon emission performance were systematically studied. The results indicated that the improved gasification methods and the synergistic effect between coal and biomass significantly improved the energy performance and emission reduction characteristics. The power efficiency of the novel system was the highest at 40.03% when the biomass blending ratio of the co-gasification sub-process was 0.8, which was 5.27% and 10.46% higher than conventional integrated gasification combined cycle (IGCC) system and biomass direct-fired power plant. The carbon-specific emissions of the novel system could be reduced to −308.1 kgCO2/MWh, achieving negative carbon utilization of fossil fuels. This novel staged coal and biomass co-gasification method heating by biomass can achieve efficient and negative carbon utilization of fossil fuels.