Feasibility Study of Production of Bio Methane from Bio Wastes in Sri Lanka and Develop Cost Model for the Production Process

Abstract: Generation of wastes as a result of expanding economic activities and change life styles of people is on the increase from recent times in Sri Lanka, especially in urban areas. The government authorities, both national and provincial, have no firm plans to manage the generation of wastes as well as safe disposal of unavoidable wastes. The wastes composition of the country is fortunately rich of biodegradable substances and it is a good indication that these wastes could be utilized in anaerobic digestion systems for the generation of biogas. Sri Lanka has over four decade’s history of using anaerobic digestion (AD) with a little expansion to deal the situation of high level of wastes being accumulated in most of the cities. Further, AD technology is not developed to the same scale as of the western countries due to various reasons related to technological know-how, economic, social and cultural practices together with misconceptions with regard to the economic benefits that could be derived from AD. This research work mainly focused on two objectives, namely to evaluate the feasibility of production of biomethane under Sri Lankan context and to develop a cost model for the production process, i.e. investor decision tool for the biomethane projects. During the study, it was considered that the overall process from input feedstock to a biogas plant to produce cleaned and upgraded biogas (biomethane), has over 95% of CH 4 . It was also considered two main end products based on purified biogas (biomethane) such as bottled biomethane and generation of electricity from combustion of biomethane on a generator coupled to an internal combustion engine or a gas turbine. Revenues of the project are made by said one product or both products. There were number of algorithms or logics made for quantifying capital cost (CAPEX) and operational expenses (OPEX) of a considered project. After estimating the revenue of such a project, net present value, internal rate of return and simple payback period for own investment were calculated (a calculation guide for those indicators provided). Those indicators are used as guides to select a successful project. It was important that co-digestion of various substrates (mainly municipal solid wastes) were considered during the development of a model.