Energy Implications of Water Transfer: Understanding Tradeoffs and Identifying Options

Abstract

Water and energy are inextricably linked. Water is essential in almost all forms of energy production, while energy is required to extract, treat, distribute, and transfer water. The bulk of the literature discusses energy requirements to treat and extract water. But less attention has been paid to the energy requirements to distribute and transfer water. Indeed, such energy requirements represent a controversial topic, and one most often incorrectly assessed due to the lack of clear methodology and to the complexity of variables involved. Distributing and transferring water using high service pumps to end users can be extremely intensive in terms of energy and economy. For instance, distributing surface water in California, USA consumes 12 times more energy than treating the same amount of water (CEC, 2005; Bennett et al., 2010). In China, the energy requirements by pumps to transfer surface water is 99%, while 1% only goes for water treatment (Wang, 2008). Moving water often includes pumping the water over hills and mountains or into storage facilities, a process that can require large amounts of energy. As weather and rainfall patterns become more difficult to predict and the world’s population continues to grow, water transfer projects could play a significant role in increasing overall resilience to water supply uncertainty and achieving water security. Plans to meet future water demands in arid regions by desalinating sea water and building pipelines to transfer water from rich regions to scarce regions will also raise the energy requirements and cost of water supply. Governments have good reasons for moving water over long distances. Yet, a headlong rush into water transfer projects could bring its own challenges. Unless planned properly, water transfer projects are likely to increase competition for both water and energy, especially where it is already scarce. This paper seeks to provide policymakers with new insights for making tradeoffs between transferring water and other water supply options. The paper also seeks to establish a method for analyzing the energy intensity of water transfer, a method which could be essential in determining future strategies of water supply.