Design of a Decentralised Biogas Reactor

With a population of 4,496,694, Kolkata is the 3rd largest megacity in India and the 20th largest in the world. But this growth has its consequences. Kolkata metropolitan area produces approximately 4000 megatons of waste every day, of which solid wastes comprise approximately 3932 megatons. These wastes are handled by the Kolkata Municipal Corporation (KMC). In the wake of the energy crisis and the depletion of fossil fuel reserves, the need to switch to non-conventional sources of energy is looming. The most notable among these is biogas, which can theoretically generate 1.4 times the annual global power requirement. Despite several works having been done in this field, biogas is still quite an untapped energy source. This paper explores the possibilities of using biogas for cooking purposes as an alternative fuel of liquefied petroleum gas (LPG), and proposes the design and construction of a decentralized biogas reactor for a small apartment building of 10–15 families with an assumed four members per family. Calculations and estimations showed that the biogas thus generated by the suggested two-stage process from solid wastes produced by the families would be sufficient to serve the purpose of substituting the cooking gas of all families residing in that building, thereby solving the dual problem of solid waste management and providing a renewable source of energy as a cheap cooking fuel.