Technical and economic analysis of a pump as a turbine for rural electrification

Electricity is one of the essential requirements for the economic development of a country. In Ethiopia, more than half of the total population does not have access to electric power. Micro-hydropower (MHP) is one of the most feasible renewable energy options for providing reliable electricity to rural areas. However, in low-income countries such as Ethiopia, the high price of a purpose-made turbine to generate electricity from MHP resources is difficult. This paper presents the feasibility study of a pump as a turbine (PAT) for MHP applications with and without impeller blade modification. The analysis was conducted in terms of initial investment cost, the net present value, payback periods, and the cost of energy. Decreasing blade thickness, blade tip rounding, adjusting blade inlet angle, and blade grooving, then comparing the result with PAT without modification and cross-flow turbine are the modification techniques considered in this research. Based on the projected system lifetime, the equivalent cost of power for the PAT and cross-flow turbines are 0.065 and 0.100 $/kWh respectively. The cross-flow turbine's payback period is 6.04 years, which is significantly longer than the PATs payback period of 3.42 years. From the entire study, it can be concluded that the MHP coupled with PAT provides a lower payback period and cheaper power production. Whereas, impeller blade modification has no significant advantage from the economic point of view. Generally, the impeller modification cost needs to be less than or equal to 25% of the initial cost of the PAT to use the less cost advantage of the PAT.