EXTENDED COST BENEFIT ANALYSIS OF BIOGAS GENERATION USING MUNICIPAL SOLID WASTE

Abstract

Attached

Solid waste is a growing problem in Sri Lanka in the absence of proper management measures. Development and implementation of a National strategy for municipal management is essential in order to reduce environmental, social and the economic problem associated with the present disposal practices. Such strategies however, need to be subjected to proper economic analysis in order to arrive at informed decisions. The present study presents an extended cost benefit analysis of a biogas generation plant that uses munipal solid waste as the raw material. To dispose vegetable market garbage available in Wattala, Kandana and Ja-ela areas productively, the 640 Mt capacity biogas/ bio fertilizer project has been housed at Muthurajawela (along Hamilton canal, Elakanda), by the National Engineering Research & Development Center of Sri Lanka (NERDC), which uses Dry Batch Anaerobic Digester Technology. Among the other biological treatment options, anaerobic digestion is the most cost effective, due to the high-energy recovery linked to the process and its limited environmental impacts. Economic analysis has been carried out to identify costs and benefits associated with the above project. Several environmental valuation methods have been applied to value the identified costs and benefits. The main benefit of reduction of municipal solid waste has been estimated as Rs 1,093,444 per year. Contingent valuation method (CVM) was used to estimate this benefit using samples from Wattal-Matnla, Ja-ela, and Peliyagoda local authorities. Green house gas (methane) emission from solid waste was estimated through Scholl Canyon model and valued using avoided global damage cost approach. Benefits of biogas as an energy source, organic fertilizers and employment benefits were estimated by market based approach. The project is viable from economy and environment point of view with net present value of Rs. 249.43 million for 20-year period with 10% discount rate. This analysis provides a justification for undertaking solid waste management strategies in a technologically environmentally and economically viable manner.