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The Interrelations of Water and Energy:
Water and Energy Fact Sheet
Compiled by the Center for Sustainable
Environments*
Northern Arizona University
September, 2005
THE SUPPLY SIDE
Water Used for Electrical Generation
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Coal and gas steam-generating electric plants in the
Interior West (MT, ID, WY, NV, UT, CO, NM, and AZ) withdraw over 650
million gallons of water daily.
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This is enough water to meet the municipal needs of
nearly 4 million people.
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A likely scenario in the near future involves the
construction of an additional 16,800 MW of capacity requiring the
withdrawal of about 116 million gallons of water daily.
Reliance on Coal-Fired Generating
Plants
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Coal-fired generating plants continue to be the
dominant power source in the Interior West.
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In 2000, coal plants consumed 94% of the freshwater
used by fossil-fuel plants in this region.
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New natural gas power plants use 40-60 % less water per
megawatt of power generated than do existing coal-fired plants.
Uses of Water in Electrical
Generation
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The primary use of water at power plants is for
condensing steam (cooling steam back to water).
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On the average, about one-half gallon of water is used
for each kilowatt produced
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75% of water for the power plants comes from surface
waters (mostly rivers) and 20% comes from groundwater. Groundwater is
the dominant water source for plants in AZ.
Thermonuclear Plants
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U.S. thermonuclear power plants withdrew 225 billion
gallons of water per day in 2002, or about 3/4 of Lake Erie.
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Thermonuclear power withdraws more water than any other
use of water in the U.S.
Low-Water Cooling Systems
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Re-circulating systems can reduce water withdrawals by
at least 95% compared to once-through systems.
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Dry cooling technologies reduce water demand and
minimize many of the water related impacts associated with power
production.
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In the US, dry cooling systems are used in over
50 operating plants and growing.
Revised Practices
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Until recently, water use and consumption have not been
significant factors in decisions related to the permitting and citing
of power plants.
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Serious drought conditions in the region have
heightened public concern about how limited water resources should
best be allocated.
-
Recently, with greater awareness and importance placed
on the value of water, permitting authorities have begun to deny
permits or condition them based on potential impacts to water
resources.
Water, Electricity and Climate
Change
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Power plants emit 40% of U.S. carbon dioxide pollution,
the primary cause of climate change.
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Climate change has the potential to greatly affect
water supply and water management, likely leading to greater risk of
drought, water shortages in summer and flooding in winter.
-
Decreased runoff equals decreased power production. In
the Colorado River, a 10% decrease in runoff reduces hydropower
production by 36%.
-
As hydropower generation decreases, producers are
likely to turn to fossil fuel plants, thereby increasing emissions
that contribute to climate change.
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From 1987 to 1992, drought in California caused
hydropower losses costing consumers $3 billion and leading to a 25%
increase in greenhouse gas emissions.
THE DEMAND SIDE
Infrastructure in the West
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Water systems in the west are energy dependent due to
the energy intensive tasks of moving large quantities of water over
long distances and significant elevations.
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Energy costs are accrued by pumping water during
access, conveyance, distribution, treatment, local distribution, end
uses, and wastewater collection and treatment.
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For a city of 50,000 people, approximately 2 million
kwh/yr are required for all water-related operations, with more than
1.6 million kwh/yr needed for pumping alone.
Saving Water Saves Energy
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Most consumers do not realize that saving water is an
excellent way to save energy.
-
Conservation at the end use stage eliminates all of the
"upstream" energy required to bring the water to the point of end use
(by avoiding conveyance, distribution, treatment, end use, and
wastewater treatment of additional water).
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The greatest energy savings and water savings come from
reducing water consumed by residential laundries and showers.
The Efficiency of
Conservation
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The amount of electricity used to deliver water to
residential consumers in Southern California is equal to 1/3 of the
total average household electric use in Southern California.
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If San Diego relied on conservation instead of
additional water from Northern California to provide the next 100,000
acre-feet of water, it would save enough energy to provide electricity
for 25% of all of the households in San Diego.
Agriculture
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Agriculture uses approximately 70% of the developed
water supply in the United States
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Pumping groundwater for irrigation uses 90% of all
electricity used on farms
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In 1995, CA agriculture used 4.4 billion kwh of
electricity for groundwater pumping and irrigation purposes, and more
than 11 billion kwh for all purposes.
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As much as 50% of water used for irrigation is wasted
due to inefficient technologies, system leaks, evaporation and
over-watering.
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It is estimated that 150,000 ha of agricultural land in
the United States has already been abandoned because of high pumping
costs brought on, in part, by reduced water accessibility due to
drought.
Water Recycling
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Reusing water is less energy intensive than obtaining
it from any other source, except local surface water.
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Orange County is constructing a water recycling system
that will use one-half the amount of energy required to import the
same amount of water from Northern California.
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From an energy perspective, a combination of
conservation and water recycling is likely the best path for meeting
growing urban water needs.
The Problem with Subsidies
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Water subsidies increase water demand, discourage
conservation and thereby increase energy use.
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Data show that per-capita water use is about 1/3 less
in areas where water users are billed based on volumetric rates rather
than fixed rates.
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Energy subsidies encourage water pumping over long
distances and accessing groundwater at depths that would not be
economically feasible if full costs were paid.
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Resource management would improve if water planning and
policy, including subsidies, reflected the critical linkages between
water and energy.
Integrating Water and Energy
Planning
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Currently, water agencies select water sources without
assessing the energy costs of transporting the water over the great
distances to users.
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Likewise, they fail to consider the energy savings of
using less water, causing high costs for consumers and wasteful
water-supply decisions.
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Looking at water use and energy use simultaneously
generates valuable insights that do not arise from separate policy
analyses of water and energy.
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Integrating energy use into water planning can save
money, reduce waste, protect the environment, and strengthen our
economy.
Compiled by Mike Madigan and Gary
Deason from the following sources:
“The Last Straw: Water Used by Power Plants in the Arid West,” Hewlett
Foundation Energy
Series, April, 2003.
“Energy Down the Drain: the Hidden Costs of
California’s Water Supply,” National Resources
Defense Council and Pacific Institute, April, 2004.
“Energy-Water Nexus,” Larry Flowers, National Renewable
Energy Lab, presentation at the Arizona Water Summit, Northern Arizona
University, August 4, 2005.
“Interrelations of Water and Electricity: The Demand
Side," Jay Golden, SMART, Arizona State University, presented by
Harvey Bryan at the Arizona Water Summit, Northern Arizona University,
August 4, 2005.
“Water Resources: Agricultural and Environmental
Issues,” David Pimental, et al, BioScience, Vol. 54, No. 10, October
2004.
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