Water and Energy Introduction
During the course of our daily lives very few of us consider the energy embedded in the water we consume. While it is more apparent when we are using heated water for showers, washing our hands, or doing the laundry, it is still easy to take for granted. The same is true on the energy side of the equation. When we turn on the lights in our homes, watch television, listen to the stereo, or use a hair drier, the amount of water used to create the electricity we are consuming is probably not the first thing on our minds. This page serves as an introduction to the conceptual framework of the connection between water and energy, or the water-energy nexus as it is often referred to.
A large amount of energy is used to pump, convey, treat, and deliver water; and much energy is consumed by the end user to heat water. It doesn’t stop there, energy is also required to collect, treat, and discharge wastewater. Additionally, water is consumed in the production of energy (primarily for cooling purposes). This connection between water and energy is not always obvious, and when water or energy resources are managed it is often with a singular focus.
Below is a general overview of the water and energy connection. A resources section is included at the bottom of the page with links to informative documents and web sites.
How much energy is embedded in water?
We know there is a significant amount of energy embedded in water. The question is, how much? While extensive research has been done in California, this question remains largely unanswered for the rest of the United States and North America. The amount of energy embedded in water likely varies greatly from region to region due to different water pumping and treatment requirements. The 2005 California Energy Commission Staff Report Paper that accompanied the 2005 Integrated Energy Policy Report estimated 19 percent of the state’s energy consumption was water related. River Network’s report The Carbon Footprint of Water estimates, “that U.S. water-related energy use is at least 521 million MWh a year—equivalent to 13% of the nation’s electricity consumption.” The Water Efficiency Committee of the Illinois AWWA section conducted a pilot project to determine the energy intensity of the state’s water supply. Utilities were surveyed and the results were compiled in the Water-Energy Nexus Survey Summary Report.
Reducing energy consumption with water efficiency also lowers greenhouse gas emissions associated with water consumption. In its report The Carbon Footprint of Water, River Network estimates that the carbon emissions related to water in 2005 were approximately 290 million metric tons, or 5% of all carbon emissions in the United States.
How much water is embedded in energy?
A lot of water is withdrawn and used for cooling in the production of energy. The majority of water withdrawn for energy production is termed “non-consumptive use” because it is returned to the same source it was removed from. However, it doesn’t necessarily return unchanged. Impacts from the cooling process include pollution and an increase in the water temperature. The United States Geological Survey's Estimated Use of Water in the United States in 2005 report estimated 41 percent of total freshwater withdrawals were for thermoelectric power.
Some water withdrawn for energy production is termed “consumptive use” because it is lost through evaporation and is not returned to the source from which it is extracted. According to a 2003 report by the National Renewable Energy Laboratory titled, Consumptive Water Use for U.S. Power Production 2 gallons of water are consumed per kWh produced. This is based on an average of thermoelectric and hydroelectric plants in the United States. A caveat here is that 89 percent of the energy produced in the United States is thermoelectric which uses an estimated 0.47 gallons per kWh, while hydroelectric is estimated to consume 18.0 gallons per kWh. There are other factors to consider as well, but it is important to note that the estimate of 2 gallons per kWh should be used with caution.
Water and Energy in California
California moves more water than any other state in the U.S. and in doing so embeds a great deal of energy in its water. According to the California Department of Water Resources, the California State Water Project (which delivers water to two-thirds of California’s population) is the nation's largest state-built water and power development and conveyance system. Portions of California rely heavily on water extracted from the Colorado River, and the residents of Southern California are additionally dependent on water resources located in Northern California. In order to transport the water from Northern California to Southern California a lot of pumping is required as gravity alone is not sufficient.
The 2005 California Energy Commission’s Integrated Energy Policy Report assessed the water/energy connection and released an accompanying document titled California’s Water – Energy Relationship. Both documents can be downloaded at the bottom of this page in the resources section and provide valuable insight into the water/energy connection in California. California’s Water – Energy Relationship is currently the most detailed study of its kind. The study found that, “water-related energy use consumes 19 percent of the state’s electricity, 30 percent of its natural gas, and 88 billion gallons of diesel fuel every year.” The report contains energy intensities of various stages of the water use cycle in Northern and Southern California. Due to the long distance water must travel to get to Southern California the study found it took 8,900 kWh/MG for supply and conveyance in that region. In stark contrast, the energy intensity of supply and conveyance in Northern California is 150 kWh/MG.
What Can Water Utilities Do?
Water utilities can recognize the water/energy connection and create water management strategies that factor both water and energy into the planning process. A great example of this is the Santa Clara Valley Water District’s 2007 From Watts to Water report. Santa Clara Valley Water District utilized the Pacific Institute’s Water to Air Model to quantify the energy savings and green house gas emission reductions resulting from the District’s water conservation and water recycling programs. The full From Watts to Water document can be downloaded below.
Water providers can also take advantage of the Alliance for Water Efficiency’s Water Conservation Tracking Tool which contains a greenhouse gas module that estimates energy savings and reductions in greenhouse gas emissions resulting from water saved through efficiency programs and plumbing codes.
Water and Energy utilities can work together to implement programs that focus on both water and energy savings. In addition to the report Tackling the Nexus: Exemplary Programs that Save Both Energy and Water that is discussed in the next section, a presentation and white paper from the Water Environment Federation's 2013 Energy and Water conference discuss collaborative efforts that focus on the end user.
Dyballa, May 2013, proceedings of Energy & Water - Integrated Solutions for Advancing Technology and Management, Water Environment Federation, Nashville, TN - White Paper
Dyballa, May 2013, proceedings of Energy & Water - Integrated
Solutions for Advancing Technology and Management, Water Environment
Federation, Nashville, TN - Presentation Slides
The AWE/ACEEE Water and Energy Collaboration
In 2010 the Alliance for Water Efficiency and the American Council for an Energy-Efficient Economy (ACEEE) received grant funding from the Turner Foundation to collaborate on water and energy. Work began on December 9, 2010 with a full day workshop including more than 50 experts in water and energy. The workshop was synthesized into a document titled, A Blueprint for Action and Policy Agenda. The blueprint addresses three broad elements: policy/codes, research, and programs, and aims to provide a framework for collaborative action, funding, and policy development.
On January 22, 2013 AWE and ACEEE announced the first-ever awards for exceptional efficiency programs that save both water and energy. The two organizations recognized a total of 12 top programs, including five exemplary award winners and seven honorable mentions. The report Tackling the Nexus: Exemplary Programs that Save Both Energy and Water contains descriptions of the 12 programs and the judging methodology.
The AWE/ACEEE water and energy workgroup is another part of the two organizations' collaborative action. In recent years, there has been a sharp increase in the area of water and energy research and the work group met regularly to explore ongoing and prospective research regarding the water-energy nexus. On July 9, 2013 the workgroup released a white paper on research needs and a database of existing research. The database extends far beyond the resources listed at the end of this page. Visit the Water and Energy Workgroup page to gain access to the white paper, database, and meeting presentations.
On October 2, 2013 ACEEE and AWE released the report Saving Water and Energy Together: Helping Utilities Build Better Programs. The report outlines areas where water utilities and energy utilities can design and administer programs together to achieve greater water and energy savings.
Summary Points of the Water and Energy Connection
- Energy is embedded in the water we consume from conveyance, distribution, treatment, and heating
- Energy is used to collect, treat, and discharge wastewater
- Water is used for energy production (primarily for cooling)
- Greenhouse gas emissions result from water consumption
- Lowering energy use will reduce the amount of water used in the production of energy
- Increasing water use efficiency will result in lower energy consumption and reduce greenhouse gas emissions
- Better data is needed to estimate the embedded energy in water for local and regional areas throughout the United States
Water and Energy Resources
AWE/ACEEE Water and Energy Work Group Page
AWE Water-Energy Nexus Research: Recommendations for Future Opportunities
AWE Water and Energy Nexus Research Database
AWE/ACEEE Blueprint for Action
Department of Energy Innovations for Existing Plants (IEP) Program’s Water-Energy Interface Web Page
Alliance to Save Energy’s Watergy Website and United States Department of Energy Watergy Software
California Public Utilities Commission - Embedded Energy in Water Studies 1, 2 and 3
River Network - Water-Energy Toolkit: Understanding the Carbon Footprint of Your Water Use
The Climate Registry (August 2015) Water-Energy Greenhouse GasTechnical Brief: Key Issues for the Developmentof the Water-Energy Greenhouse Gas Guidance
United States Department of Energy (June 2014) The Water-Energy Nexus: Challenges and Opportunities
AWE Comments (May 2014) on DOE Proposed Rulemaking for Automatic Commercial Ice Makers - Docket EERE-2010-BT-STD-0037 - RIN 1904-AC39
U.S. Senate Energy and Natural Resources Committee (May 2014) The Energy-Water Nexus: Interlinked Resources That Are Vital for Economic Growth and Sustainability
Ajami, Newsha and Truelove, Cynthia (April 2014) A Water-Energy Research Agenda: Building California's Policy Foundation for the 21st Century
Congressional Research Service (January 3, 2014) Energy-Water Nexus: The Energy Sector’s Water Use
Electric Power Research Institute and Water Research Foundation (November 2013) Electricity Use and Management in the Municipal Water Supply and Wastewater Industries
Pacific Institute (September 2013) Water-Energy synergies: Coordinating Efficiency Programs in California
Congressional Research Service (August 30, 2013) Energy-Water Nexus: The Energy Sector’s Water Use
Western Resource Advocates (August 2013) Conservation Synergy: The Case for Integrating Water and Energy Efficiency Programs
National Geographic (2013) Water Demand for Energy to Double by 2035
Western Resource Advocates (2012) A Powerful Thirst: Managing the Electricity Sector’s Water Needs and the Risk of Drought
Michael Webber (July 23, 2012) Will Drought Cause the Next Blackout? New York Times
Idaho Rivers (2012) Treasure Valley Energy Outlook: Why Domestic Water Use Matters
Sanders, K. and Webber, M. (2012) Evaluating the energy consumed for water use in the United States
Ontario, Canada (2012) Water and Electricity Conservation Incentive Partnership
POLIS (2012) From Stream to Steam: Emerging Challenges for BC's Interlinked Water and Energy Resources
Illinois Section of the American Water Works Association (2012) Water-Energy Nexus Survey Summary Report
GEI Consultants (2012) California’s Water-Energy Nexus: Pathways to Implementation
River Network (2012) Burning Our Rivers: The Water Footprint of Electricity
California Public Utility Commission (2011) Embedded Energy in Water Pilot Programs
World Policy Institute (2011) The Water-Energy Nexus: Adding Water to the Energy Agenda
Environmental Law Institute (2010) Mapping the Energy-Water Policy Landscape
National Conference of State Legislatures (2009) Overview of the Water-Energy Nexus in the United States
United States Government Accountability Office (2009) Improvements to Federal Water Use Data Would Increase Understanding of Trends in Power Plant Water Use
River Network (2009) The Carbon Footprint of Water
AWE President and CEO Mary Ann Dickinson’s Presentation at the IAPMO 2009 Emerging Technology Symposium:
Part 1: http://www.youtube.com/watch?v=1PLZo6gS5mQ&feature=related
Part 2: http://www.youtube.com/watch?v=yiCH2lxuynM
Part 3: http://www.youtube.com/watch?v=cssJSIEggPA
Part 4: http://www.youtube.com/watch?v=OffHKHMlDS0&feature=related
Part 5: http://www.youtube.com/watch?v=QwDvwxbU03E&feature=related
ICF International (2008) Water and Energy: Leveraging Voluntary Programs to Save Both Water and Energy
Scientific American Special Edition (2008) Earth 3.0: Energy versus Water: Solving Both Crises Together
Santa Clara Valley Water District (2007) Watts to Water – Climate Change Response through Saving Water, Saving Energy, and Reducing Air Pollution
California Energy Commission (2005) California’s Water – Energy Relationship
California Energy Commission (2005) Integrated Energy Policy Report
(Of particular interest - Chapter 8: Integrating Water and Energy Strategies)
Natural Resource Defense Council and Pacific Institute (2004) Energy Down the Drain
Pacific Institute (2004) Urban and Agricultural Water to Air Models
National Renewable Energy Laboratory (2003) Consumptive Water Use for U.S. Power Production