Energy Nexus (Sep 2023)
Micro-hydropower systems for smallholder farmers in rural communities of Taraba state, Nigeria: Feasibility study, system analysis, design and performance evaluation (Part II)
Abstract
This article deals with the feasibility study, system analysis, design, and performance evaluation of micro-hydropower systems for smallholder farmers in rural communities of Taraba state in Nigeria. The hydrologic data used to determine the available flow rate to produce the required hydraulic power were obtained from GEO Global Water Sustainability (GEOGloWS) Service. The principle of Darcy and Weisbach, applied in the Colebrook and Haaland’s equations were employed to analytically estimate the hydraulic head loss due to friction in the penstock, installed trash rack, and fitted valves. The Hydro-Power Plant (HPP) Design professional tool was used to size the different constituents of the proposed micro-hydropower plant, and to evaluate its overall performance. With a low net head of 5.2 m, and a maximum discharge of 1.21 m3/s, two vertical Kaplan turbines with combined peak power of 106 kW were obtained. The Kaplan turbines drive two 6-pole, 50-Hz asynchronous generators with nominal power of 50 kW each. The simulation results from the HPP design tool show that the system achieved a minimum efficiency of 56% with the flow ratio of 0.2, and maximum efficiency 86.1% with flow ratio ranging from 0.6 to 0.8. The Renewable Energy Project Analysis Software (RETScreen) Expert was utilized to perform cost, cash flows, financial sensitivity, and risk analysis of the proposed micro-hydropower plant in Wurno-Gassol. The RETScreen Expert estimated the risk level is at 10%, with minimum and maximum levels of confidence on risk associated with equity payback to occur in 4.6 years and 13.2 years respectively, with median level of confidence in year 7.2. Furthermore, the risk level on energy production cost is estimated at 10%, with minimum and maximum levels of confidence sitting at 101 USD/MWh and 140 USD/MWh respectively, with the median level of confidence at 118 USD/MWh.
