Development of a procedure and tool for retrofit hydropower evaluation at South African dams

South Africa is in a critical power situation and is in dire need of additional generation capacity. Thus, renewable energy sources such as wind, solar and hydropower should be evaluated to identify high-potential and cost-effective sites. Rivers in South Africa, as a water-scarce country, are already heavily impounded, meaning that there are limited sites available for conventional hydropower generation. Instead, novel solutions such as retrofitting hydropower installations to existing infrastructure, like existing dams, are required. To estimate the retrofit hydropower potential at dams, a set of five tools was developed using Python 3, known as the University of Pretoria Retrofit Hydropower Evaluation Software (UP-RHES). The UP-RHES screens potential sites where historic flow records are available, then downloads the required flow records from the national database and performs a first-order hydraulic assessment of the site, as well as a first-order life cycle cost analysis. By applying the UP-RHES to 118 dams operated by the Department of Water and Sanitation (DWS), it was found that a total estimated hydropower potential of 128 MW with an annual energy output of between 385 and 469 GWh exists at South African dams. The Vaal, Pongolapoort, Goedertrouw and Blyderivierpoort Dams were found to be feasible sites with a combined capacity of 77 GWh/annum.