The Top Banner

Energy-Water Nexus

Energy and water security has become a national and global priority. The continued security and economic health of the United States or any country depend on a sustainable supply of both energy and water because these two critical natural resources are so closely linked.

The production of energy requires large volumes of water while the treatment and distribution of water is equally dependent upon readily available, low-cost energy. In 2000, irrigated agriculture and thermoelectric generation withdrawals of fresh water were approximately equal in the U.S. Electricity production requires about 190,000 million gallons of freshwater per day, accounting for over 40 percent of all daily freshwater withdrawals in the U.S. In many regions of the U.S., the indirect use of water (home lighting and electric appliances) is approximately equal to direct use (water lawns and taking showers).

Water is a vital and integral element for the development of U.S. and global energy resources and utilization. It is used in energy-resource extraction, refining and processing, and transportation. All of these are vitally interdependent because of their relation to critical infrastructure. For example, water plays an integral role in electric-power generation, where it is used directly in hydroelectric generation and extensively for cooling and emissions scrubbing in thermoelectric generation. In calendar year 2000, thermoelectric power generation accounted for 39 percent of all fresh water withdrawals in the U.S., or about the same as water withdrawals for irrigated agriculture (34 percent — withdrawals are water diverted or withdrawn from a surface-water or groundwater source). Water withdrawals for thermoelectric power are dominated by power plants that return virtually all withdrawn water to the source and account for 3.3 percent of total freshwater consumption (3.3 billion gallons per day) and represented over 20 percent of non-agricultural water withdrawal. Although this water is returned at a higher temperature and with other changes in quality, it remains available for future use. A number of power plants, including most of those built since 1980, withdraw much less water but consume much of what they withdraw through the process of evaporative cooling, which causes greater pressure on water supplies.

Current trends of water use and availability indicate that meeting future water and energy demands to support continued economic development will require improved utilization and management of both energy and water resources. Primary concerns include:

  • Increasing populations require more food and energy; this will cause direct competition between the two largest water users (energy and agriculture) for limited water resources.
  • Population growth and economic expansion projections indicate the U.S. will require an additional 393,000 MW of new generating capacity (equivalent to about 1,000 new 400 MW plants) by the year 2020, which is unlikely to occur.
  • Potential environmental and ecological restrictions on the use of water for power generation.
  • Emerging contaminants such as pharmaceuticals in drinking water that are beginning to reach potentially harmful levels, that once reached, may cause irreversible damage.
  • Potential terrorist attacks on power grids and water treatment and distribution systems. The ability to meet the increasing demand for affordable water and energy is being seriously challenged by these and other emerging issues. This is true for almost all countries.

It is not just the Middle East or Darfur anymore that has serious problems; the energy-water problem is global, from the 10 major U.S. cities that are running out of water (Los Angeles, Houston, Phoenix, San Antonio, San Francisco, Ft. Worth, Las Vegas, Tucson, Atlanta, and Orlando) to Brazil who is beginning to lose virtual water due to agricultural exports. As the natural resource base declines globally, so too does the ability to provide low-cost energy for the world’s poorer impoverished groups. Our goal at TinMore Institute is to help provide solutions to energy and water problems.

Energy production requires an abundant, predictable, and reliable source of water. However, good quality water is already in short supply throughout much of the world — especially in water-stressed areas. Agriculture uses approximately 70 percent of total water in the U.S., which compares similarly to other countries. There is little that can be done to trim agricultural consumption long-term despite new water-saving technologies — due to population increase, agricultural productions must dramatically increase. However, this will cause increased pressure on both water and energy supplies and resources.

The electricity industry ranks second as the largest user of water. Electricity production from fossil fuels and nuclear energy requires 190,000 million gallons of water per day (39 percent of all freshwater withdrawals in the U.S., with 71 percent attributed to fossil-fuel electricity generation). Coal, the most abundant fossil fuel, accounts for 52 percent of U.S. electricity generation; each kWh (kilowatt hour) generated from coal requires the withdrawal of 25 gallons of water. However, this is far less than water use needed for extraction of oil from oil shale. This implies that indirect use of water (home lighting and electric appliances) is approximately equal to direct use (drinking water, water lawns, and taking showers). According to the 2001 National Energy Policy, population and economic growth in the U.S. alone will require 393,000 MW of new generating capacity by the year 2020. This will further strain U.S. water resources. To supply this demand would require 1,000 new, 400 MW power plants or, about 70 trillion gallons and 88 trillion gallons for fossil/biomass/waste and nuclear power plants, respectively. How much water is that? To illustrate, Lake Mead requires about two years of annual flow from the Colorado River to fill the reservoirs to capacity, which is about nine trillion gallons. Thus, additional power plant water requirements, for fossil/biomass/waste plants, would be enough to fill Lake Mead about eight times.

This scope is difficult for most to comprehend. Additionally, given current economic problems across the nation and within all states, construction of these facilities is very unlikely, which means decreasing energy supplies per capita. It would therefore appear that the most probable solution will be strict limits on energy and water use and/or rolling blackouts to provide necessary supplies. This will help conserve both resources. Continued lack of a formal energy policy, which should be joined to a water policy, will only exacerbate this process. However, due to political self interests, party partisanship, and related issues, it appears unlikely the U.S. will develop an effective energy policy; after all, the efforts first began in 1930 and yet no policy exists.

There is a problem with this scenario, which underscores whether a stable, affordable supply of water will exist to support future U.S. electricity demands and continued economic development at a time when additional jobs are greatly needed:

  • U.S. and global populations are expected to increase significantly; accessible freshwater supplies will not. These supplies are finite; two of the few options to increase or supplement these water supplies are desalination and drinking water treated from city sewage and wastewater as is done in Singapore. The latter is unappealing to most Americans. Also, while water is a renewable resource, it is not an expandable resource.
  • Energy necessary for treatment and distribution of water accounts for about 80 percent of its cost; an insufficient supply of affordable energy will have a negative impact on both the price and availability of water. Increasing gas prices will have a dramatic impact on water availability and pricing.
  • Population migration and increase in relation to energy demand do not always coincide with water availability. For example, during the 1990s in the U.S., the largest regional population growth, 25 percent, occurred in one of the most water deficient regions, the mountain west.
  • Water availability is a serious issue in water-stressed regions of the U.S., particularly in the southeast, where population has increased by nearly 14 percent since 1990. In comparison, the water-rich northeast has experienced only a two percent population growth. In other countries such as Darfur, Jordan, and Israel, this problem is more aggravated.
  • An increasing population will require more electricity and more food. More food requires more energy from fossil fuels and more water for crop production. This will create serious competition between the nation's two largest water users for limited water supplies (energy and agriculture). As an example, ethanol produced from corn requires nearly 2,500 liters of water to produce one kilogram (300 gal per lb) of ethanol. And, in the U.S., corn commonly is grown in areas experiencing a 20 to 50 percent growth in population. This combination changes irrigation and crop management practices and significantly stresses water resources. Similar trends occur globally.
  • Proposed restrictions on the use of water for power generation to protect fish and other aquatic organisms could result in both increased costs of electricity and potential energy shortages. This may be especially true since ‘green’ advocates are calling for the dismantling of existing dams. A line will be drawn — either man is more important or fish and other aquatic life are. Who will make this choice and what will the consequences be?

The critical interdependence between water and energy is inseparable; one resource cannot exist in an industrial economy without the other. Also, the interdependence between these critical infrastructure and others, as well as economic industries and sectors is far deeper than most imagine. If the serious threat of population growth and competition between these resources is not frightening, it should at least be of grave concern (The above text was extracted from the book “Water Security: Conflicts, Threats, Policies – used by permission).

Copyright © 2010-2013 TINMORE INSTITUTE All Rights Reserved. Unauthorized Distribution or Reproduction is Forbidden.