With rapid population growth there is an increased trend of global energy consumption. On a global scale most of the energy supply is currently generated by fossil fuels with all the subsequent consequences including depletion of non-renewable energy resources (e.g. oil, coal and natural gas), greenhouse gas emissions and climate change. With respect to the increasing global demand for cheap, reliable and environmentally safe energy, there is a need for innovative technologies and an increase in renewable energy share. Biomass is a unique renewable resource with a wide range of uses and a huge potential. However its relevance for food industry poses an ethical dilemma. Therefore, finding the possible solutions for more efficient biomass use are increasingly important. In this paper, results of a study identifying parameters and conditions necessary for increasing the quality of outgoing gases from biomass gasification and digestion processes are presented. A methanation process is simulated for upgrading the quality of the gases. It is a reaction where carbon oxides present in the gases react with hydrogen to produce methane. The reaction is condition-dependent, therefore a mathematical model is developed for simulating parametric values that influence the process. In the paper, the simulation results are presented.