Thermodynamic study on energy crops thermochemical conversion to increase the efficiency of energy production

•Miscanthus giganteus and Arundo donax are characterized by high volatilization.•Difference between reaction temperatures is affected by composition of energy crops.•Arundo donax has higher exergy efficiency of syngas based on CH4 production.•Arundo donax has the lower biomass chemical exergy compared to Miscanthus giganteus.•The lower equivalance ratio produces higher exergy efficiency of the gasification.