Drawing The Water And Energy Connection
In the necessary flurry to reduce carbon emissions, water issues are arguably taking a back seat. Scarcity and quality of water present cause for concern, but saving water doesn't seem to excite like saving energy does.
Consider what must happen for water to reach your sink. First, it must be extracted, lifted, and pumped. Then it is treated and pressurized for distribution. Once water reaches the vicinity of your house, further energy is used to circulate, heat, and cool it. Then as water slips down the drain, it is collected and treated by a wastewater system, and the process starts over again.
In states that desalinate or transport water over long distances and heights, energy consumption is even greater. In California, water is the single largest use of electricity, accounting for 19 percent of total electricity use. Halfway across the world, many states in India now use half their electricity to pump water from depths of a kilometer or more.
The flip side is true too. Producing energy requires vast amounts of water: power plants, biofuels, and hydro-power all rely on water to run. In fact, the drought in the U.S. southeast this past year threatened to close nuclear plants in North Carolina and literally cut Georgia's hydroelectric power generation by half.
So you can see, saving water presents benefits far beyond what appears on the surface.
Here are some large-scale, profitable opportunities:
Agriculture consumes 80 percent of U.S. freshwater, and in many cases wastes half of it or more. Methods such as accurate water measurement and soil moisture monitoring, laser-leveling fields, using conservation tillage to retain soil moisture, switching to low energy precision application sprinklers, lining canals, and employing subsurface drip irrigation where possible could save upwards of 40 percent of agriculture’s water use while improving crop yields and saving energy.
The average U.S. city loses between 10 and 25 percent of its water through old pipes. In developing nations, leaks in urban water systems can waste 50–70 percent of the water that should be flowing through their pipes.
Boston Water and Sewer Commission has relayed or relined over 300 miles of aging pipes, reducing the amount of water being lost through system leaks by 50 million gallons per day. This effort together with the installation of water-efficient plumbing fixtures and devices enabled Massachusetts to cancel its plans to dam the Connecticut River, saving its 2.1 million customers more than $500 million in capital expenditures.
Bob Wilkinson, professor and water director at University of California's Donald Bren School of Environmental Science and Management, believes the key to capturing energy and water savings lies in a simple measurement: the energy intensity of water. This measurement calculates, on a whole-system basis, the energy required for the use of a given amount of water in a specific location. Wilkinson argues that using this measurement on a wide-scale would encourage energy and water utilities to co-invest in water efficiency programs.
Technologies do not appear to be the limiting factor. Perhaps understanding the nexus between energy and water will provide the motivation we need to save water.
Let's get busy implementing solutions.
By: Rocky Mountain Institute, Maria Stamas, Analyst
Image Credit:: Ramón C Purcell Photography