A high-efficiency negative-carbon electricity generation system based on coal and biomass complementary gasification and the Allam cycle

Fossil fuels continue to dominate the global electricity supply, and traditional power generation technologies generally face challenges, including low efficiency and high greenhouse gas emissions. This research proposes a novel power generation system based on the complementary gasification of coal and biomass, coupled with the Allam cycle. This novel system increases gasification efficiency and reduces CO₂ emissions by co-gasifying coal and biomass. The use of the Allam cycle for power generation eliminates the costly, energy-intensive water-gas shift and carbon capture stages in conventional systems, resulting in higher electricity production efficiency, lower operating costs, and the potential to achieve negative carbon emissions. This study conducted experiments to investigate the coal-biomass co-pyrolysis characteristics and the gasification performance of the resulting mixed char. Using Aspen Plus software, a full-process simulation model was developed to comprehensively evaluate the system with respect to thermodynamics, environmental impacts, and power generation costs. The results show that the novel gasification method increases CGE by 15.02 percentage points compared to traditional coal gasification processes. The energy efficiency and exergy efficiency of this novel system are 46.28% and 41.89%, respectively, representing improvements of 13.64 percentage points and 10.98 percentage points over the reference system. In terms of greenhouse gas emissions, the novel system achieves the CSE of −71.18 kg/MWh, meeting the goal of negative carbon emissions during power generation. The results of the economic analysis indicate that the LCOE of the novel system is 0.060 $/kW·h, representing a 40% reduction compared to the reference system.