TODAY’S STUDY: HOW THE NATION’S WATER CRISIS IS A NEW ENERGY OPPORTUNITY
Burning Our Rivers; The Water Footprint of Electricity
Wendy Wilson, Travis Leipzig & Bevan Griffiths-Sattenspiel, April 2012 (River network)
It takes water to produce electricity. As many Americans retreat to air-conditioned environments to get out of the heat, the flame increases under our limited freshwater resources. The electrical energy used to create our comfort zones requires massive withdrawals of water from our rivers, lakes and aquifers to cool down nuclear, coal and natural gas power plants. Some of this water is evaporated while the majority of this water is warmed up—causing thermal pollution—killing aquatic life, increasing toxic algae blooms and decreasing the sustainability of our water supplies.
Thermoelectric energy (including coal, nuclear and natural gas) is the fastest growing use of freshwater resources in the country. The U.S. Geological Survey (USGS) reports that 53% of all of the fresh, surface water withdrawn from the environment for human use in 2005 went to operating our thirsty electrical grid. Water behind dams is not included in USGS numbers. So, while all other sectors of society are reducing per capita water use and overall water diversion rates, the electrical industry is just getting started.
This report is a snapshot of the current water impacts of electrical production and an introduction to the choices we face as a nation trying to sustain water and energy in a warming world. Many watersheds in the United States (U.S.) are already running out of water to burn—especially in the Southeast, the Great Lakes and in many parts of the West. Over the last several years, Georgia has experienced water stress because Georgia Power’s two nuclear plants require more water than all of the water consumed by residents of downtown Atlanta, Augusta and Savannah combined. In 2011, the Union of Concerned Scientists (UCS) reported that, in at least 120 vulnerable watersheds across the U.S., power plants are a factor contributing to water stress.
As a nation, we have “water-friendly” energy options. Energy efficiency and water conservation programs are crucial strategies that can help protect our waterways from the impacts of electricity production. Expanding the deployment of wind energy and photovoltaic (PV) solar power could vastly reduce water- use conflicts in some regions. And we must change the technologies we use in existing power plants. Energy companies could conserve more water by modernizing “once-through” cooling systems than could be saved by all of our nation’s residential water conservation programs combined.
But instead of moving towards greater water efficiency and use of renewables, we are trending towards an electrical grid that uses more water and is less reliable. Without stronger federal water use standards, thermoelectric plants may continue using water-intensive cooling technologies. At the same time, water uncertainty is causing cities to explore new water sources such as desalinization, deeper wells and longer pipelines—all of which would increase electrical use. Across the country “non-conventional” drilling for natural gas has raised concerns about water quality. In Colorado, natural gas “fracking” operations have actually begun to compete with farmers for water. The water footprint of coal-fired power plants will only increase with new carbon capture and sequestration (CCS) technologies.
Based on the available published water-use information, we calculate that in 2009 the water footprint WF of U.S. electricity was approximately 42 gallons per kilowatt hour (kWh) produced. An average U.S. household’s monthly energy use (weighted by cooling technology and fuel mix) requires 39,829 gallons of water, or five times more than the direct residential water use of that same household. This estimate does not include major portions of the lifecycle of electrical production for which we could not find documentation. As the world’s largest electrical consumer, the U.S. needs to consider the sustainability of this course before investing in more water-intensive electrical infrastructure.
Today, our thirsty electric grid carries pollutants into our rivers and causes algae-blooms and fish kills. But, there are other paths. According to our calculations, eliminating ‘once-through’ cooling—by itself—could reduce the water footprint of thermoelectricity by more than 2/3rd. Increasing wind and PV solar energy to 40% of the grid would have a similar effect and reduce consumptive water use by 11%. Taken together, these two actions could reduce the water footprint of thermoelectricity by 82% and consumptive water use by 27%. While there are site-specific limitations and trade-offs to consider, our society stands to benefit from a wider discussion of how water saved in the energy sector might be used to meet future needs, grow food or restore fisheries and water quality…
Summary of Recommendations
Our heavy reliance on “burning” our freshwater resources creates a host of pollution and water scarcity problems across our country. Understanding the local impacts of our energy use is a critical step towards reducing water pollution (especially thermal pollution) and restoring our rivers, streams, lakes and aquifers. We have many policy options including closing old thermo-electric plants, integrating water and energy planning for greater efficiency and developing greater access to the electric grid for low-water renewables such as wind and PV solar.
In general, moving away from fossil fuels towards renewable energy sources will help stretch our limited freshwater resources. But not all renewable energy development has low water impacts and disturbing natural land, for any type of energy development alters a site’s hydrology and potentially threatens rare ecosystems. Non-water related concerns with renewable energy projects, particularly centralized solar plants (either PV or concentrating solar thermal) and wind, include the loss of natural habitat from the large areas of land required for solar panels or wind turbines and direct wildlife conflicts (i.e., sage grouse habitat, migratory bird and bat casualties). These are real tradeoffs that must be considered on a site- specific basis. Using rooftops, disturbed land and parking lots for solar arrays may help minimize some of these concerns.
There are other important technological changes that can reduce water pollution and overuse. For example, in Ohio, four inefficient and outdated coal-fired plants will soon be closed. The cooling water for those antique “once-through” coal-fire facilities was coming directly from Lake Erie for over 50 years, being returned to the Lake much warmer, contributing to algae blooms. According to a study by USGS, 70% of all water taken from Lake Erie for human use is for thermoelectric plants. A substantial co-benefit to closing these plants will be reduced fish kills, algae blooms and an aquatic dead zone in America’s heartland.
We can also take a closer look at decommissioning older dams in places where there are more water- efficient ways of meeting electrical demand or adding turbines to existing dams not currently being used to produce power. Many hydropower dams are owned by the federal government, authorized directly by Congress and rarely subjected to a rigorous cost-benefit analysis before being built.
Local watershed organizations and freshwater protection groups need to get more involved in energy conservation programs. Groups can get involved in water quality permitting and help increase community awareness of the associated problems. Municipal water suppliers and farmers need to be engaged in energy planning. Given the need for better energy planning and the potential for water-use conflicts, all stakeholders need to make their voices heard.
If we change our electrical infrastructure across the country with water in mind, we can expect a more reliable energy grid, better fishing and recreation, more secure public water supplies and lower greenhouse gas emissions. Presented with this list of potential benefits, leaders in many communities might ask, “Why did we wait so long?”
In the Western U.S., all water flows towards irrigators and cities, turning hydropower turbines along the way. The reservoirs associated with hydropower dams lose water through evaporation, fragment rivers and reduce water quality. In many places in the Eastern U.S., the biological health of rivers and lakes is heavily compromised by thermal pollution associated with thermoelectric cooling.
Electricity—as we generate it today—depends heavily on access to free water. The impact to our freshwater resources is an external cost of electrical production. What the market considers “least cost” electricity is often the most water intensive. There are clearly some low water technologies and some water hogs. For example, wind and PV solar technologies have by far the lowest water-use factors (from zero to 231 gallons used per MWh produced) and hydropower, coal and nuclear have the largest water use factors (ranging from 14,811 to 440,000 gallons per MWh).11
The actual water footprint of electricity varies tremendously by fuel, generating efficiency, cooling technology, climate, geography, the body of water used for cooling and the physical layout of the power plant site. Our summary comparisons of water-use factors by fuel type are found in Table 1 (see p. 10). These are based on estimates of the prevalence of various cooling technologies in the U.S. electrical grid. We weighted these factors based on 2009 data from NETL.
Finally, Table 2 (see p. 11) is weighted on the prevalence of each fuel in the U.S. electrical grid. As a result, we calculate that an average kWh of electricity in the U.S. used or consumed 41.6 gallons of water in 2009. In reality, the amount of water used or consumed to produce a kWh varies widely, highest in places where evaporative losses are greatest and least where power is supplied by PV solar and wind.
An average household uses just under 1,000 kWh of electricity each month based on the 2010 U.S. Census data (958 kWh for a 2.4 person household). Table 3 (see p. 12) shows that, based on the mix of fuels and cooling technologies, the average U.S. household indirectly uses 39,829 gallons of water per month through the associated water footprint of electricity.
For comparison, that same household would use 7,336 gallons directly each month for residential purposes.12 Therefore, we can say that we use five times more water indirectly through electrical production than through all of our household sinks, toilets, dishwashers, washing machines, faucets and hoses combined.
This report doesn’t attempt to quantify the enormous environmental consequences of electricity production and its associated water use. Arguably, every body of surface water in the country has been impacted by mercury contamination from coal-fired plants. Fish nd aquatic species are the “canary” in the coal mine—but the coal mine is our drinking supply. We believe a stronger recognition of all of the associated impacts of electrical production will help us focus on possible ways of protecting our water supplies.