Sustainable development of an area is highly dependable on reliable electrical energy supply. Due to the depletion of fossil fuels, and the contamination of the environment due to the generation of energy from primary energy sources, the energy sector is reforming and shifting towards a new era where renewable energy sources will become the primary focus of attention. At present, energy researchers and government organizations are interested in a distributed generation system using local renewable energy sources to electrify the rural areas situated far away from our mainland. Here, a biomass-based power supply system is being analyzed and compared with other potential power supply systems for Sagar Island. Sagar Island is the world’s largest river-based island situated in the Sundarban deltaic complex, where the potential of biomass is huge due to the availability of natural forests, barren coastal areas full of weeds, agricultural by-products, cattle manure and waste materials from other sources. Here, an attempt has been made to provide sustainable electrical energy to the rural areas of the isolated Sagar Island for the sustainable development of the local people. This was done by means of using biomass and a fuel cell based electricity generation system.