ABSTRACT
The ‘water-energy nexus’ has recently become a hot topic at water seminars. There is a growing recognition that water policy and energy policy must somehow be related, because energy production requires water, and water supply costs energy. In the past, in fact until today, water and energy policies have most of the time been disconnected altogether. Whereas efforts have been undertaken to improve both water-use efficiency and energy efficiency, we can observe two interesting trends. First, the water sector is becoming more energy-intensive; think for example of the energy needed for pumping groundwater from deeper and deeper, for constructing and moving water through large inter-basin water transfer schemes and for desalination of salt or brackish water. Second, the energy sector is becoming more water-intensive – especially because of the increasing focus on biomass as a source of energy. All energy scenarios for the coming decades show a shift towards an increased percentage of bioenergy. In this chapter, I will not address the full scope of the water-energy nexus and all the challenges that lie herein. I will focus on the question of how much water is involved in the production of biofuels and how much water it would take to drive our cars, trains and airplanes on bioenergy. I will also briefly consider the water footprint of hydroelectricity, another form of energy with a relatively large water footprint, and the water footprint of other energy carriers (fossil fuels, nuclear, solar and wind).
