Hydropower accounts for about 16% of the world’s electricity supply. Although dams often have big environmental and social impacts, proponents of hydropower regard it as a comparatively clean, low-cost and renewable form of energy. It has been debated whether hydroelectric generation is merely an in-stream water
user or whether it also consumes water, in the sense of effectively taking away water from the river. In this report we provide scientific support for the argument that hydroelectric generation is in most cases a significant
water consumer. The study assesses the blue water footprint of ydroelectricity – the water evaporated from manmade reservoirs to produce electric energy – for 35 selected sites. The aggregated blue water footprint of the selected
hydropower plants is 90 Gm3/yr, which is equivalent to 10% of the blue water footprint of global crop production in the year 2000. The total blue water footprint of hydroelectric generation in the world must be considerably larger if one considers the fact that this study covers only 8% of the global installed hydroelectric capacity. Hydroelectric generation is thus a significant water consumer. The average water footprint of the selected hydropower plants is 68 m3/GJ. Great differences in water footprint
among hydropower plants exist, due to differences in climate in the places where the plants are situated, but more importantly as a result of large differences in the area flooded per unit of installed hydroelectric capacity.
We recommend that water footprint assessment is added as a component in evaluations of newly proposed hydropower plants as well as in the evaluation of existing hydroelectric dams, so that the consequences of the water footprint of hydroelectric generation on downstream environmental flows and other water users can be evaluated. Sustainable development of hydropower requires the accounting and internalization of all external costs including water consumption. Internalization means that the economic and environmental costs of the water consumed are charged to the operator of a hydropower plant and included in the price of hydroelectricity. It should thereby be acknowledged that water consumption costs vary within the year and across river basins,
since the degree of water scarcity and competition over water depend on the period within the year and local circumstances.
|Name||Value of water research report series|
|Publisher||UNESCO-IHE Institute for Water Education|