Design of a stand-alone 1000-kW biogas power plant from codigestion of organic waste and microalgae grown in a tubular photo bioreactor at Bomaka-Buea

Abstract

Buea is connected to the south interconnected grid (SIG) of Cameroon. But the power supply is unreliable, not accessible to all and of very low quality. In addition, solid municipal waste generated in Buea is poorly collected by Hysacam and dumped at Musaka with no further valorization. There is an acute need to improve on the quantity, reliability and quality of the power supplied to inhabitants of Buea as well as to improve on the environmental management system of the town. In this study a project is proposed to design a stand-alone 1000-kW biogas power plant from the codigestion of organic fraction of solid municipal waste with microalgae (Chorella Sorokiniana) grown in tubular photo bioreactor (PBR) in Bomaka-Buea. As far as electrical energy production is concerned, the aforementioned anaerobic biological treatment unit will produce almost 9311.88 MWh/y. Assuming an average electricity consumption of 3 to 4 MWh/y/household the annual produced electrical energy from the anaerobic digestion (AD) unit could supply almost 3000 to 4000 households in the Municipality of Buea. So by treating the 39% of annual organic waste produced in Buea it can cover between 31.3% and 31.8% of Buea municipality's electrical energy demand. With a levellized cost of electricity at 0.265 $/kW and a net present value of 25.3million dollars if this energy is sold to the national grid then the annual profit of energy production will be around $4,188,888/y (assuming a selling price of 0.36 $/kWh) that is valid now in Cameroon.