Biogas has become one of the most attractive pathways among the renewable energy sources essential to address major modern challenges such as climate change and energy depletion in recent years. Biogas derives from the degradation of organic materials through anaerobic digestion by microorganisms. Such organic materials generally come from waste feedstocks. Therefore, besides being a sustainable replacement for fossil fuels, biogas helps control waste. Agricultural and industrial residues, municipal organic waste and sewage sludge are thus common feedstock sources, including seeds, grains and sugars, lignocellulosic biomass such as crop residues and woody crops, or high carbohydrate algae. Because of its versatility in usage and storage space, biogas plays an significant role in managing potential electricity grids. Through biogas production and utilisation, our society can go deeper into green energy applications. This Chapter will give an introduction the the current energy sector and where biogas can be used as a substitute for decarbonisation of the energy sector.