Joint design of floating solar plant and dam operating policies for waterborne epidemics control: an assessment on the Kariba dam

With more than 200 dams currently under construction in the Sub-Saharan region, hydropower is expected to dominate the African renewable energy market in the coming decades. Even though the construction of new dams has been widely recognized as a key factor in promoting energy security, damming rivers also augments the volume of stagnant water, inevitably enhancing the transmission of malaria by creating new vector breeding habitats. The interdependence between large dams and malaria transmission constitutes an extremely critical public health challenge in Africa. Nowadays, managing drawdown rates into reservoir operation as a malaria control measure appears a viable solution to reduce the spread of the virus near large reservoirs, notwithstanding undesirable outcomes in terms of hydropower generation. In this regard, recent technological developments in the field of floating solar photovoltaic installations open the path for flexible hydropower operation by boosting photovoltaic energy generation using the same electricity transmission infrastructure. The aim of this study is to propose an integrated framework, where the optimal floating solar sizing and reservoir operations are jointly designed for minimizing malaria diffusion without compromising the ability of the energy sector to fulfill energy demands. The framework employs Evolutionary Multiobjective Direct Policy Search into a novel approach to floating solar photovoltaic size planning, which internalizes the operation design problem. The potential of the proposed framework is tested in the Zambezi river basin, where the Kariba dam is mainly operated for hydropower production, with considerable negative health effects in the proximity of the reservoir. Numerical results show that design alternatives coupling reservoir operation with floating solar photovoltaic largely dominates pure management solutions in terms of malaria spread and energy generation. Besides, the relatively limited (from 0.2 to 1.5% of the total lake area) optimal extent of the photovoltaic plant highlights the potential economic benefits of increasing the penetration of this technology in Sub-Saharan Africa, with capital costs balanced by boosted energy income within the first seven years from the initial investment.