Numerical analyses into carbon circularity through integrated biomass gasification and electrochemical CO2 conversion to formic acid

The present study proposes an integrated gasification-electrochemical CO 2 reduction system for the co-production of syngas and formic acid, hence, reducing CO 2 emissions and promoting carbon circularity. Unlike the conventional gasification systems which focus primarily on syngas production, the proposed framework integrates downstream electrochemical recycling for the produced gas to convert the CO 2 into formic acid, providing additional carbon utilisation. A 2D Computational Fluid Dynamics (CFD) integrated model composed of two separate sub models (gasification and electrochemical) was established. The model investigated the influence of equivalence ratio (ER) on key performance parameters including lower heating value (LHV), H 2 production, CO 2 reduction, formic acid formation, gasification and carbon conversion efficiencies. In addition, a multi-criteria decision-making (MCDM) analysis was conducted to select the optimum working conditions. Based on the MCDM, an ER of 0.3 achieved the highest ranking. Compared to the stand-alone systems, the integrated system working under the suggested optimum ER produced lower CO 2 emissions by 27 vol%, higher formic acid by 31.7 wt%, higher H 2 production by 8.6 vol%, and higher gasification efficiency by 8.5 %. As a result, system integration significantly enhanced the overall process performance and improved fuel quality and energy recovery. The results indicate improvements in carbon utilisation and formic acid formation, however, before studying system scale-up and industrial deployment, some challenges must be addressed. This includes produced gas cleaning, renewable electricity requirements, electrochemical systems scaling, and economic and environmental viability studies.