Pacific Southwest, Region 9
Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations
The use of water and the use of energy are intricately intertwined. The extraction, treatment, distribution, and use of water followed by the collection and treatment of wastewater require a lot of energy; likewise, the production of energy—particularly hydroelectric and thermometric power generation— requires a lot of water.
Saving Energy Saves Water
Water is used to turn turbines for hydropower, to produce steam for thermoelectric power, and to cool equipment by absorbing the waste heat produced by power generation with once-through or closed-loop cooling systems. Closed-loop systems reuse water rather than returning it to the source.
Each kilowatt-hour (kWh) of thermoelectric generation requires the withdrawal of approximately 25 gallons of water, primarily for cooling purposes. However, while thermoelectric facilities withdraw tremendous amounts of water, they actually consume far less. That consumption is caused by evaporation. On average, 2 gallons of water are lost to evaporation for each kWh consumed at the point of end use, though this number varies greatly State by State, depending on the energy-mix. In Arizona, for example, 7.85 gallons of water are lost to evaporation per kWh consumed.
Withdrawn Water— water removed from the ground or diverted from a surface-water source for use.
Consumed Water—the part of withdrawn water that is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment.
By reducing the amount of energy we use, we reduce the amount of water evaporated in the production of that energy.
Saving Water Saves Energy
Energy is used in five stages in the water cycle:
- Extracting and conveying water: Extracting water from rivers and streams or pumping it from aquifers, and then conveying it over hills and into storage facilities is a highly energy intensive process. In California, the State Water Project (SWP) pumps water almost 2000 ft over the Tehachapi Mountains! The SWP is the largest single user of energy in California. It consumes an average of 5 billion kWh/yr, accounting for about 2 to 3 percent of all electricity consumed in California.
- Treating water: Water treatment facilities use energy to pump and process water.
- Distributing water: Energy is needed to transport water.
- Using water: End users consume energy to treat water with softeners or filters, to circulate and pressurize water with circulation pumps and irrigation systems, and to heat and cool water.
- Collecting and treating wastewater: Energy is used to pump wastewater to the treatment plant, and to aerate and filter it at the plant. On average, wastewater treatment in California uses 500 to 1,500 kilowatt-hours per acre-foot.
By reducing the amount of water we use, we use lessen our demand on the energy-intensive systems that deliver and treat water.
In addressing climate change and increasing resource scarcity, we hope you help us spread the following message:
Saving Water & Energy Reduces Greenhouse Gas Emissions!
On Region 9’s Energy and Water Efficiency website, you can learn about various ways that drinking water and waste water facilities, industry, businesses, municipalities, residences/individuals, agriculture, and thermoelectric power generators can save water and energy and, by doing so, reduce greenhouse gas emissions.
Carpe Diem West is a network of experts, advocates, decision makers, and scientists who are addressing the profound impacts the growing climate crisis is having on water in the American West.
Energy Demands on Water Resource: Report to Congress on the Interdependency of Energy and Water presents background information on the connections between energy and water, identifies concerns regarding water demands of energy production, and discusses science and technologies to address water use and management in the context of energy production and use.
Energy Down the Drain: the Hidden Costs of California's Water Supply shows how integrating energy use into water planning can save money, reduce waste, protect our environment and strengthen our economy.
Energy versus Water: Solving Both Crises Together is a 2008 Scientific American article that discusses how water is needed to generate energy and how energy is needed to deliver water.
Chapter 8 (on page 138) of the CEC’s Integrated Energy Report explores ways to integrate water and energy strategies in California.
Climate Change Impacts on Water-Resources
The National Water Program Strategy: Response to Climate Change provides an overview of the likely effects of climate change on water resources and the nation’s clean water and safe drinking water programs. This final Strategy also describes over 40 specific actions the National Water Program intends to take to adapt program implementation in light of climate change.
In Climate Change Adaptation Strategies for California’s Water, the California Department of Water Resources recommends a series of adaptation strategies for state and local water managers to improve their capacity to handle change.
The Water Research Foundation has established a Climate Change Clearinghouse for the water community.
A key goal of EPA's National Water Program Strategy: Response to Climate Change is to engage States, Tribes, and others in addressing the complex issues posed for water by a changing climate. To enhance cooperation among State and Federal water program managers on climate, a charter has been drafted to establish a State Climate Change Council made up of State water program managers who will work with the National Water Program at EPA. The draft charter which outlines the Council's purpose, membership, and operation can be found at EPA's Strategy Implementation site, under Adaptation Products.
Proceedings and Transcripts from the "EPA Workshop on Water Infrastructure Sustainability and Adaptation to Climate Change"
Water and Energy Use in the United States
Every five years, the USGS estimates Water Use in the United States.
The Energy Information Administration provides official energy statistics.
If you would like to suggest or provide additional resources, please contact Charlotte Ely (Ely.Charlotte@epa.gov).
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