Combining Floating Solar Photovoltaic Power Plants and Hydropower Reservoirs: A Virtual Battery of Great Global Potential

Abstract

Artificial water reservoirs have been created over history for a variety of purposes such as flood control, seasonal water storage for irrigation, fishing, hydropower generation, energy storage, etc. Globally, hydropower represents still the largest share of renewable electricity generation, with over 1170 GW of capacity installed, thereof 328 GW is hydro Run-of-River capacity, and the rest is hydro reservoir based (141 GW of which is hydro pumped storage), controlled to different degrees. These reservoirs cover a surface of approximately 265.7 thousand km2 with the potential to host 4400 GW of floating photovoltaic (PV) power plants at 25% reservoir surface coverage and generate approximately 6270 TWh of electricity. This capacity can be extended to 5700 GW and about 8000 TWh of electricity if all reservoirs (hydropower and for other purposes) are covered at 25%, in both cases generating already more electricity than hydropower from reservoirs at about 2510 TWh. The flexibility of operation of hydro reservoir based power plants and their current connection to grids facilitates a “virtual battery” consisting of supplying the electricity demand with solar energy during peak irradiation hours, while balancing grids with hydropower during low/no irradiation times and providing a zero impact area for PV power plant deployment. The characteristics of the “virtual battery” are investigated and presented in this study. The PV power plants also could prevent approximately 74 billion m3 of water evaporation, further benefiting hydropower production and water conservation, increasing water availability by an estimated 6.3%, adding an estimated 142.5 TWh of production to reservoir-based hydropower plants.