Response of southern African growing hydropower systems to climate change and penetration of solar and wind

The Southern African Power Pool (SAPP) - a twelve-country regional cooperation for planning and operating an interconnected electricity grid - aims to ensure affordable electricity access by 2040, with high penetration of low-carbon energy resources. A key focus is to substantially expand hydropower systems in major river basins (e.g., Zambezi, Congo), including the installation of some of the world's largest dams. However, it is not clear how the planned hydropower development may impact grid performance, system costs, and need for other generation technologies in a changing climate, in addition to hydropower's known susceptibility to hydroclimatic variability (e.g., droughts) and socio-ecological impacts. At the same time, the high potential and recent cost reduction of solar and wind power could provide cost-effective alternatives if their generation variability is managed. To explore these questions, we employ a modelling framework combining hydrologic and electricity grid-expansion models. The hydrologic model is forced by hydro-meteorological variables (e.g., precipitation, temperature) retrieved from several global circulation models and simulates future streamflow conditions and hydropower availability at major existing and planned dams. These hydrologic model outputs are used in the grid-expansion model to evaluate optimal generation capacity investment plans under different scenarios of climatic conditions (cool-wet to warm-dry) and penetration of wind and solar. Our results inform the strategic planning of hydropower systems and explore alternative investments in solar and wind, accounting for affordability and climatic risk in a region that is poised to undergo rapid economic growth and energy infrastructure expansion.