The world’s energy consumption is projected to increase rapidly that will cause depletion of known fossil fuel resources, global warming and threat to future energy security. Biomass is likely to play a significant role in the future energy systems replacing conventional fuels due to strict regulations for reducing greenhouse gas (GHG) emissions as well as contributing as additional resource in the global energy mix. Biomass is processed in a bio-refinery facility for polygeneration of bio-energy products such as biofuels, heat, and power. Polygeneration system can be categorized based on various process routes producing electricity or biofuels or even providing only heat e.g. biomass gasification system, integrated biogas production with combined heat and power by treating organic waste, tri-generation systems etc. The successful commercialization of bio-refinery systems for polygeneration require pilot plants to demonstrate improvements in energy efficiency, substantial biofuel, heat and power production potential from biomass together with reduced cost. From the sustainability perspective, bio-refinery systems show numerous economic, social and environmental benefits including diversification in biomass resources and bio-energy products.