Towards carbon neutrality of calcium carbide-based acetylene production with sustainable biomass resources

Acetylene is produced from the reaction between calcium carbide (CaC₂) and water, while the production of CaC₂ generates significant amount of carbon dioxide not only because it is an energy-intensive process but also the raw material for CaC₂ synthesis is from coal. Here, a comprehensive biomass-to-acetylene process was constructed that integrated several units including biomass pyrolysis, oxygen-thermal CaC₂ fabrication and calcium looping. For comparison, a coal-to-acetylene process was also established by using coal as feedstock. The carbon efficiency, energy efficiency and environmental impacts of the bio-based calcium carbide acetylene (BCCA) and coal-based calcium carbide acetylene (CCCA) processes were systematically analyzed. Moreover, the environmental impacts were further evaluated by applying thermal integration at system level and energy substitution in CaC₂ furnace. Even though the BCCA process showed lower carbon efficiency and energy efficiency than that of the CCCA process, life cycle assessment demonstrated the BCCA (1.873 kgCO₂eq kg-prod⁻¹) a lower carbon footprint process which is 0.366 kgCO₂eq kg-prod⁻¹ lower compared to the CCCA process. With sustainable energy (biomass power) substitution in CaC₂ furnace, an even lower GWP value of 1.377 kgCO₂eq kg-prod⁻¹ can be achieved in BCCA process. This work performed a systematic analysis on integrating biomass into industrial acetylene production, and revealed the positive role of biomass as raw material (carbon) and energy supplier.