Abstract: A triphasic biomethanation process, to convert starch or sugary agricultural feed stock into a methane rich gas mixture for facilitating generation of biogas to be used as kitchen fuels, electrical power or transportation from renewable biomass in a cost-effective manner. The process brings about conversion of starch-rich or sugar-rich biomass into methane through three stages, namely, hydrolysis, acidogenesis and methane formation. The present invention deploys enzymes/physical/microbial parameters to hasten the hydrolytic reaction in the first stage. It also deploys microbial consortia that have been enriched for a targeted feed in order to speed up the process of conversion. The formation of alcohol from starch is prevented, as a result of the consortia deployed, the conversion efficiency is substantially improved and the retention time is also reduced to cut the capital cost of the plant.