Economic and environmental assessment of electricity generation using biogas from organic fraction of municipal solid waste for the city of Ibadan, Nigeria

Abstract

In this paper, biogas recovery from organic fraction of municipal solid waste for the purpose of electricity generation is presented with the objective of determining its economic and environmental benefits for the city of Ibadan, Nigeria. Two methods of biogas recovery technologies (i.e., anaerobic digestion and landfill gas recovery technologies) were considered. The environmental impact was performed using life cycle assessment technique while the economic assessment was determined using total life cycle cost, levelised cost of energy, net present value, internal rate of return and payback period. Sensitivity analysis was conducted to investigate the influence electricity generation efficiency, capacity factor, per capita waste generation rate, discount rate, population growth rate and waste collection efficiency on the economic viability of the two technologies. Some of the results indicated that in a span of 20 years (i.e., 2017–2036), the waste generation potential of the city of Ibadan was estimated between 477,001 and 966,897 tons. The methane yield for anaerobic digestion and landfill gas recovery technologies were determined to be about (104.66–212.15) x 106 m3/yr and (22.65–127.65) x 106 m3/yr, respectively. Also, the electricity generation potential ranged between 321.73 and 652.15 Gigawatt-hour for anaerobic digestion and 63.25–436.18 Gigawatt-hour for landfill gas recovery technologies. The economic indicators showed that both technologies are economically viable as they presented positive net present values. The net present value for anaerobic digestion was 834.12 million US dollar while that of landfill gas recovery was 489.26 million US dollar. The levelised cost of electricity generation was between 0.0681 and 0.0336 US dollar per kilowatt-hour for anaerobic digestion technology while it ranged from 0.2411 to 0.0350 US dollar per kilowatt hour for landfill gas recovery technology. The payback period, internal return and the total life cycle cost were 5 years, 19.3% and 413.68 million US dollar for the anaerobic digestion and 7 years, 23.4% and 288.05 million US dollar for landfill gas recovery technology. This paper intends to serve as first-hand technical information to potential investors, government agencies, policy makers and potential non-governmental organisations to enhance optimal investment in biogas to energy technologies in Nigeria.