Total annual gross water loss vs total annual energy production of hydropower plants

In 2016, a total of 42 billion cubic meters of water was lost through evaporation in hydropower reservoirs in Africa. A huge amount compared to the 1.2 billion cubic meters lost from all the other fuel types combined. In the same period, hydropower accounted for 15% of Africa’s total energy production. The ratio of annual water loss (from a hydropower reservoir) versus energy production (of the associated hydropower plant) describes somehow the water efficiency of a hydropower site. The ratio varies from region to region and depend on the reservoir’s surface area and evaporation rate, and on the produced energy of the associated hydropower plant. A better performance (lower ratios, i.e. ratios below 1) in terms of reduced water losses through evaporation per produced energy unit can be achieved at hydropower sites characterized by decreased reservoir surfaces and increased energy production. In contrast, unfavourable, higher ratios occur with water losses higher than the associated hydropower energy production rates. This map shows the water loss / energy production ratio (mcm/GWh) for each hydropower generating country in Africa (country's total water loss versus country's total annual energy production of hydropower plants) for year 2016.