A feasibility and implementation model of small-scale hydropower development for rural electrification in South Africa

Abstract

Small scale hydropower used to play a very important role in the provision of energy to urban and rural areas of South Africa. The national electricity grid however, expanded and offered cheap, coal generated electricity and a large number of hydropower systems were decommissioned. Unfortunately, large numbers of households and communities will not be connected to the national electricity grid for the foreseeable future due to high cost of transmission and distribution systems to remote communities, the relatively low electricity demand within rural communities and the current expenditure on upgrading and constructing of new coal fired power stations. Today, small hydropower projects are the most commonly used option to supply electricity to isolated or rural communities throughout the world including countries such as Nepal, India, Peru and China. It was hypothesized that it is technically possible to provide small?scale hydropower (SSHP) installations for rural electrification in South Africa, and that for specific configurations of penstock diameter, penstock length and transmission line lengths, SSHP installations are more feasible for rural electrification than local or national electricity grid extension or even other energy sources such as diesel generators. The objective of the study was to identify potential sites for the development of feasible small-scale hydropower plants within the OR Tambo District Municipality in the Eastern Cape, and the uMzinyathi District Municipality in Kwa-Zulu Natal, South Africa. The objective was the development of a feasibility and implementation model to assist in designing and financially evaluating small-scale hydropower plants for several similarly identified potential small-scale hydropower installations in South Africa. The implementation model describes steps to be followed in identifying a technically possible and feasible opportunity to develop a small?scale hydropower site for rural electrification, and categorises them into three different sections, namely Site Selection, SSHP and Cost Assesment, which combine to form the implementation model. Continuous referral from the subsequent sections of the study back to the implementation model provides a comprehensiveness to the model which allows for a sustainable implementation of the SSHP project from the conceptual phase to the commissioning of the plant. Several designed small-scale hydropower plants were economically evaluated on Net Present Value, Internal Rate of Return, Levelised Cost of Energy, Financial Payback Period and Capital Cost Comparison (CCCR). It was observed that a low levelised cost is not always associated with a low CCCR and vice versa. The levelised cost of small-scale hydropower is lowered by developing sites with shorter penstock lengths for higher elevation differences, to obtain a higher head while minimizing penstock lengths and capital costs. From the financial analysis of several designed installations, generic formulae for costing a small-scale hydropower plant were developed. By keeping specific variables constant, design charts for technically executable and financially feasible small-scale hydropower plants were developed by assuming constant penstock diameters, penstock lengths and potential head available. The outcome of this study proved the initial hypothesis. From the feasibility analysis and developed design charts it was concluded that the levelised cost of small-scale hydropower projects indicate that the cost of small-scale hydropower for low energy generation is high compared to the levelised cost of grid connected electricity supply. However, the remoteness of small-scale hydropower for rural electrification and the cost of infrastructure to connect remote rural communities to the local or national electricity grid provides a low CCCR and renders technically implementable small-scale hydropower projects for rural electrification feasible on this basis.