Techno-economic and environmental assessment of coal co-gasification with alternative carbon sources and CO2 capture and co-utilization for sustainable syngas production

Syngas derived from coal gasification is an important resource for chemicals and fuels production globally. However, extensive use of coal emits large volumes of CO 2 and other pollutants to the environment. Conversely, alternatives such as natural gas, biogas, purified biomethane, and captured CO 2 present cleaner methods for transitioning to sustainable energy. This study conducted a techno-economic and environmental assessment of integrated gasification pathways to determine the cost and environmental optimal performances. One conventional coal gasification and seven alternative co-gasification steady-state process models were developed and simulated in Aspen Plus® v14. A full factorial design was used to investigate the impact of feedstock blending ratios and CO 2 recycle fraction on greenhouse gas emissions and syngas minimum selling price. The effects of plausible future green hydrogen prices and carbon taxation on the syngas minimum selling price were also evaluated. Co-gasification of coal and natural gas in a fixed-bed gasifier, with downstream CO 2 capture and utilization, demonstrated the best transitional potential, achieving a 25.4% lower syngas minimum selling price and lowering greenhouse gas emissions by 44.3% compared to the conventional base case. A syngas minimum selling price evolution analysis under green hydrogen and carbon tax future market conditions revealed that carbon taxation is the primary driver of economic convergence between coal‑only and alternative configurations. These results demonstrated that coal–methane co-gasification with CO 2 utilisation offers a robust and economically strong pathway for the staged decarbonisation of coal-based syngas production.