Gasification performance of various microalgae biomass – A thermodynamic study by considering tar formation using Aspen plus

•A new integrated biomass and tar gasification model are developed using Aspen Plus.•Different types of microalgaes considered as biomass feedstocks.•The controlled use of O2 improves the gasification performance and system efficiency.•The use of steam gives high cold gas efficiency and hydrogen production. A new combined biomass and tar gasification model is developed using Aspen Plus. The proposed gasification process consists of four main units: (i) pyrolysis, (ii) combustion, (iii) gasification, and (iv) CO2 absorption. The model predicted product compositions show good agreements (relative error