Water Footprint (WFP) in Hydropower Plants Using Observed Meteorological Datasets: The Case of the Funil Hydropower Plant, Southeast Brazil

Water footprint (WFP) has been used to indicate the efficiency and sustainability of water resources. In hydropower plants (HPP), WFP is the water evaporated from the reservoir / the energy produced in a period (monthly or annually), in m3.GJ−1. The major issue in this case is that the water stored in the reservoirs is exposed to solar radiation and is evaporated, being a very significant water amount that is not used in other economic activities. The WFP in a HPP has been calculated using average meteorological datasets from the closest station, which has resulted in a biased calculation. However, WFP can also be calculated by considering net evaporation, the net water footprint (NWFP). In this chapter, we present a case study involving a HPP in the Grande River basin, southeast Brazil. WFP and NWFP were calculated over two consecutive hydrological years using observed local weather datasets and the temperature of the reservoir’s water. The FPP has shown 29 (WFP) and 13 m3GJ−1 (NWFP) (the latter was 55% lower). Our results have demonstrated a reasonable efficiency of the water use for electric energy generation in this facility. In addition, when using the weather datasets in the reservoir’s area and the thermodynamics of the reservoir, WFP calculation becomes more robust and reliable.