The water–energy nexus is the nearly inextricable linkage between water and energy. Every step of the water cycle—producing, moving, treating and heating water, then collecting and treating wastewater—consumes energy. Just as producing water requires a lot of energy, harnessing energy requires lots of water. Almost every power source demands water in one form or another, be it to produce petroleum or wash coal, grow and distill biofuels, or to drive and carry waste heat away from steam turbines. During recent drought years, some power plants for example have had to run below full capacity owing to a lack of water for cooling.
We envision a future where water utilities use less energy to deliver water more valuably to customers who better understand the energy implications of the water they use.
Even though these two resources are mutually dependent, they have to date largely been kept apart. Utilities siting power plants and politicians deciding how to allocate energy priorities often do so without consideration of the water impact. Likewise, water utilities, regulators, and consumers often make water decisions without fully considering the energy impact of their plans.
The Center for Water–Energy Efficiency is dedicated to breaking down the conceptual, technological, and regulatory barriers between water and energy. At a time when both energy and water are under increasing stress, viewing both holistically adds tremendous value: water saved translates to energy saved, and energy saved means water saved.
Roughly 20% of California’s electricity and over 30% of its natural gas goes to water. We are working hard to help water consumers to conserve the water they use and water utilities to determine the energy intensity of the water they deliver. Determining water’s energy intensity accurately will make water conservation something that can be commodified and traded on the California–Québec international carbon market, helping the climate problem and further stimulating conservation measures. By giving new conservation incentives and promoting rate structures that promote conservation without threatening water utilities’ financial stability, we hope to enable water utilities to implement conservation measures without fear of financial instability and annual rate hikes. We envision a future where water utilities use less energy to deliver water more valuably to customers who better understand the energy implications of the water they use.
Our work on water consumed in energy production is significant in that we have produced the world’s first nation-by-nation technology-by-technology assessment of water consumed in the energy sector. Reviewing this pioneering work shows the remarkable water intensity of all the world’s energy sources, from low (solar PV and wind power) to high (coal and biofuels) water use. Having this information available means more intelligent energy planning and policy-making: energy sources that make perfect sense in one region may make little sense in another with different water availability. We hope energy planners worldwide will be able to determine more intelligently the right directions to steer energy planning and policy decisions to select appropriate technologies for a economically, environmentally, and socially sustainable future.