Micro Hydropower Potential Assessment and Full Scheme Design of Chisiche River in Jimma Zone

Abstract

In Ethiopia, many remote villages or farms are still not connected to the national grid because of the high cost of distributing electricity. Micro-hydropower projects have proved to be an economically efficient alternative in an effort to power small towns of Ethiopian like Limushay town where the population is sparsely distributed. In this study, a ‘run of river’ is selected for which there is little or no water storage available for rural applications by means of micro hydropower plants. The methodology used in the research work includes actual site measurements and hydrology of the site. Soil and Water Assessment Tool (SWAT) model is used for the catchment area, precipitation, and evaporation. Financial analysis is integrated using RETScreen software to determine the variability of the project. In this thesis, the assessment of micro-hydropower potential, selection and design of different hydraulic structures and electromechanical equipment of ‘Chisiche’ river are done. The gross head available in the site is 22.75m with a net head of 21.01m and design discharge of 0.25m3/s. The possible installed capacity and annual energy generation of the power plant designed for the site is 44.59kW and 390.6GWhr, respectively. The structure includes the weir intake, headrace, forebay, settling basin, penstock, and tailrace. The headrace is designed as a rectangular type of channel-shaped with a length of 20 m and a flow depth of 0.5 m. The inclined pressure shaft penstock with a diameter of 347mm and a length of 50 m is provided for direct flow to the power house. A cross-flow turbine system is selected with an efficiency of 79% having a good response to a wide range of variable flow. Generator with an installed capacity of 50KW three-phase synchronous is recommended with turbine shaft speed rated as 750rpm and frequency of 50Hz. The cost of the project and the bill of quantities are done using the recent cost of structural materials and electromechanical equipment. The investment cost is 1,388,749.5birr with a payback period of around 5 years. Net Present Value is greater than zero and the Benefit-Cost ratio is greater than 1, this is the indication of a potentially practicable project. This study revealed that environmental friendly, technical, and financially viable development of the Chisische River for hydropower generation.