The European Union aims at a transition towards a renewable energy system by strengthening biomass exploitation. Within P2G concept bio-methanation of CO2 from biomass conversion systems with H2 enables an overall emission reduction. For this methanation process the amount of gases serving as potential CO2 sources islimited due to impurities like O2 or N2 in many industrial exhaust gases. Purification technologies for CO2 are costly and very energy consuming. By using an enzymatic CO2 capture process the energy demand and the costs will be reduced and “impure” gases like exhaust gases from e.g. biomass combustion or CHP-units will be applicable. Thus, these gas streams serve as alternative carbon sources and have the potential to substantially increase the exploitation of biomass for the production of energy carriers. Such efficient P2G systems are mandatory towards a fossil fuel free society and will strengthen the role of renewable energy in the future European energy system.