Analysis of blue water footprint of hydropower considering allocation coefficients for multi-purpose reservoirs

Abstract

Hydropower is a source of clean, low-carbon renewable energy. However, because of the evaporation of water from reservoir surfaces, a large amount of water is lost, which may result in water scarcity. As for multi-purpose reservoirs, there is no accepted method to allocate water losses among their various functions. Ignoring the multiple requirements of the different ecological service functions of the reservoir will inevitably lead to overestimation of the hydropower blue water footprint (WF). In this study, taking Miyun Reservoir Hydropower Station during 1985–2013 as an example, we showed that distributing water loss between multiple uses by calculating an allocation coefficient greatly reduces the amount of water allocated to electricity production. For spatial analysis, we collected published data on 68 hydropower stations and found that the linear correlation coefficient of WF and spatial variation is 0.94, whereas for four multi-purpose reservoirs calculated using allocation coefficients is 0.99. Further, a temporal analysis indicated that the time step of evaporation calculation may affect the calculation of the blue WF. We also confirmed previous studies showing that the research area we analyzed has experienced severe water scarcity over the years. The results of this study can provide an effective tool for comprehensive evaluation of multi-purpose hydropower stations, and calculation of the environmental costs of hydropower development as clean energy.