Catalytic calcium-looping gasification of biochar with in situ CO2 utilization with improved energy efficiency

•Catalytic calcium-looping gasification of biochar was demonstrated.•The integration can realize the effective capture and in situ conversion of CO2.•The decarbonation kinetics, CO yield and conversion stability were all improved.•The C-assisted CO2 preferable dissociation occurred on the K-doped CaO surface.•This simple, cheap and energy-efficient process allows large scale application.