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OverviewoftheWaterEnergyNexusintheUS

Overview of the Water-Energy Nexus in the United States

2/19/2014

Introduction

Niagara FallsState legislatures and natural resource managers have traditionally addressed water and energy as two separate issues. However, water and energy are deeply connected and sustainable management of either resource requires consideration of the other. Thus, resource managers and lawmakers across the country are beginning to take a comprehensive and interdisciplinary approach to the management of water and energy. This report provides overview information about the nexus between water and energy and provides a summary of state legislation addressing this issue.

  • Total water withdrawals from all sources in the United States in 2011: 405,868 gallons per person (World Bank, 2011 and United States Census Bureau, 2011)
  • Electric power consumption in the United States in 2011: 13,246 kWh per person (World Bank, 2011)

Water Energy Nexus Overview

Water and energy are critical, mutually dependent resources—the production of energy requires large volumes of water and water infrastructure requires large amounts of energy.

Water is required to generate energy. Thermoelectric cooling, hydropower, energy mineral extraction and mining, fuel production (including fossil fuels, biofuels, and other non-conventional fuels), and emission controls all rely on large amounts of water. In the United States, the thermoelectric generating industry is the largest withdrawal user of water. According to USGS, 349 billion gallons of freshwater were withdrawn per day in the United States in the year 2005. The largest use, thermoelectric, accounted for 41 percent of freshwater withdrawn at 143 billion gallons per day (BGD). However, freshwater consumption for thermoelectric purposes is low (only 3 percent) when compared to other use categories such as irrigation, which was responsible for 81 percent of water consumed.

  • Water withdrawal: The total volume removed from a water source such as a lake or river. Often, a large portion of this water is returned to the source and is available to be used again.
  • Water consumption: The amount of water removed for use and not returned to its source.

Water supply also requires energy use. A large amount of energy is needed to extract, convey, treat, and deliver potable water. Additionally, energy is required to collect, treat, and dispose of wastewater. In 2010, the U.S. water system consumed over 600 billion kWh, or approximately 12.6 percent of the nation’s energy according to a study by researchers at the University of Texas at Austin. The study found water systems use about 25 percent more energy than is used for residential or commercial lighting in the U.S.

Water and energy are both multifaceted issues with many variables impacting their supply, demand, and management. Lawmakers should consider the following variables which add complexity to the management of water and energy:

  • Growing population: According to a 2012 United States Census Bureau projection, the U.S. population could reach 400 million people by 2051. Population growth affects energy use through increases in housing, commercial floor space, transportation, and economic activity. The U.S. Energy Information Administration estimates that total electricity consumption will grow from 3,841 billion kWh in 2011 to 4,930 billion kWh in 2040, an average annual rate of 0.9 percent. With a higher generating capacity, the U.S. will require additional water withdrawals.
  • Agriculture: Feeding a growing population may require greater agricultural water use.  Agriculture accounts for approximately 37 percent of total freshwater withdrawals in the U.S., and 81 percent of water consumption.
  • Geographical water demand: Water supply and demand are not geographically linked.  From 1990 to 2010, the second largest regional population growth, 13.8 percent, occurred in the West, which is one of the most water deficient regions in the United States. Additionally, water consumption in the western U.S. is much higher than other regions due to agricultural demands. It is estimated that it takes over 1 million gallons of water a year to irrigate one acre of farmland in arid conditions. In other words about 86 percent of irrigation water withdrawals were in western states in 2000.
  • Climate Change: Climate change could affect water supply and electricity use. Warmer or colder weather patterns could result in increases or decreases in energy use. Changes in precipitation in a region could increase or decrease the ability to store water, agricultural production and water use, and overall water supply.

States are beginning to assess their energy options and promote policies that allocate financial support to a diverse range of technologies to encourage responsible, sustainable energy production. States are also becoming aware of the limitations to accessible water, and as our energy demands grow, competition for water among municipalities, farmers, industrial and power suppliers will increase. Water and energy are linked at both the supply side (electric generation and water/wastewater facilities) and the end-use side (residential, commercial, industrial, and agriculture sectors). In order to sustain energy production and a dependable water supply, the U.S. must gain a detailed understanding of the interdependencies of water and energy systems and balance the needs of all users. State lawmakers and constituents will be critical in this process given their responsibility formulating policy, convening stakeholders, facilitating negotiations, and ratifying reached agreements.

dopted from "Energy demands on Water Resources" U.S. DOE Report to Congress on the interdependency of energy and water.

Figure 1. Examples of interrelationships between water and energy.

Adopted from "Energy demands on Water Resources" U.S. DOE Report to Congress on the interdependency of energy and water.

 

 

 

 

Figure 2. Water withdrawal and consumption by energy type.

This chart compares the water withdrawal and water consumption factors (in gallons per MWh) for fuel-based electricity generating technologies.

Fuel Type

Cooling

Technology

Median Withdrawal

Median Consumption

Nuclear

Tower

Generic

1101

672

 

Once-through

Generic

44350

269

 

Pond

Generic

7050

610

Natural Gas

Tower

Combined Cycle

225

205

 

 

Steam

1203

826

 

 

Combined Cycle with CCS

506

393

 

Once-through

Combined Cycle

11380

100

 

 

Steam

35000

240

 

Pond

Combined Cycle

5950

240

 

Dry

Combined Cycle

2

2

Coal

Tower

Generic

1005

687

 

 

Supercritical

634

493

 

 

IGCC

393

380

 

 

Supercritical with CCS

1147

846

 

 

IGCC with CCS

642

549

 

Once-through

Generic

36350

250

 

 

Supercritical

15046

103

 

Pond

Generic

12225

545

 

 

Supercritical

15046

42

Biopower

Tower

Steam

878

553

Source: NREL, 2011
 

Explanation of Cooling Systems Types:

  • Tower – Water is circulated through the generating facility to collect heat waste and then to a tower to allow the heat to be released into the atmosphere. Because tower systems use a closed-loop water design, water withdrawals are less than once-through systems.  However, some water is lost to steam, leading to greater water consumption than the once-through system.
  • Once-through – Cool water is taken from a nearby source (e.g., river, lake, aquifer, or the ocean), circulated once through the generating facility to absorb excess heat, and is returned to its original source. Because water is used one, this type of system requires greater withdrawals, but consumes less than a tower cooling systems
  • Pond – A man-made body of water used to supply cooling water to a nearby power plant. Similar to a once-through system, but water is allowed to cool in a pond before being re-used in the system. This results in greater evaporative loss than a once-through system.  
  • Dry – Dry systems use air instead of water to cool the steam exiting a turbine. There is no net water consumption, and the initial charge of working fluid is expected to last for the life of the system.

Explanation of Technologies

  • Combined Cycle - An assembly of heat engines that work in tandem from the same source of heat, so that the exhaust of one engine is used as the heat source for another. This system extracts more useful energy from the heat and increases the system's overall efficiency.
  • Steam - Water is heated into steam, which spins a turbine that drives an electrical generator. After it passes through the turbine, the steam is condensed and the resulting water can be used again.
  • IGCC (Integrated Gasification Combined Cycle) - Coal is combined with oxygen and steam to produce syngas. The gas is then burned in a gas turbine to produce electricity. Waste heat from the gas turbine is recovered to create steam which drives a steam turbine, producing additional electricity.
  • Supercritical - New pulverized coal combustion systems – utilizing supercritical technology – operate at increasingly higher temperatures and pressures and therefore achieve higher efficiencies than conventional pulverized coal combustion units and significant CO2 reductions.    
  • CCS (Carbon Capture and Storage) - is the process of capturing waste carbon dioxide from large power plants, transporting it to a storage site, and depositing it where it will not enter the atmosphere, normally an underground geological formation.

Summary of Water Energy Nexus Statutes

At least nine states—Arizona, California, Colorado, Connecticut, Nevada, South Dakota, Washington, West Virginia and Wisconsin—have statutes that recognize the nexus between water and energy. Arizona, California and Nevada have statutes that mention the appropriation of water for generating electricity. A detailed summary of the statutes in each state follows below.

State Statutes Summary
Arizona Ariz. Rev. Stat. Ann § 45-156; Legislative authorization for appropriation of water to generate power: change in use (Note: Parts of this statute held unconstituional in San Carlos Apache Tribe v. Superior Court 193 Ariz. 195, 972 P.2d 179 (1999).) Requires legislative authorization for the appropriation or use of water to generate over 25,000 horsepower of electric energy.
  Ariz. Rev. Stat. Ann § 45-166; Approval for appropriation of waters for generating electric energy 34,100 acre feet of water per year maybe appropriated for the operation of thermal generating plants. The operation of thermal generation plant means the use of water for the thermal generation of electric energy.
  Ariz. Rev. Stat. Ann § 45-1450; Consideration of water uses in studying flood control projects All beneficial uses of the state's water and other natural resources, such as, irrigation, generation of electric energy, municipal and industrial consumption of water and power, recharge of groundwater basins, preservation and development of fish and wildlife resources, and recreational facilities, shall be considered when studying flood projects
  Ariz. Rev. Stat. Ann § 45-2242; Functional powers of the board  Gives the County Water Authority Board the ability to acquire electricity or other forms of energy necessary to transport water or operate authority projects.
  Ariz. Rev. Stat. Ann § 48-4853; Functional powers of the board Gives the Active Management Area Water District Board the ability to acquire electricity or other forms of energy necessary to transport water or otherwise operate the projects of the district.
California  Cal. [Public Resource] Code § 25008; State policy; energy and water conservation; alternate supply sources; energy or water facilities at state-owned sites Intent of the Legislature to promote all feasible means of energy and water conservation and all feasible uses of alternative energy and water supply sources. In recognition of recent and projected increases in the cost of energy and water from traditional sources, it is the policy of the state to use available resources at state facilities which can substitute for traditional energy and water supplies or produce electricity or water at its facilities when use or production will reduce long-term energy or water expenditures. Outlines criteria for analyzing proposed actions.
  Cal. [Public Resource] Code § 25402; Reduction of wasteful, uneconomic, inefficient or unnecessary consumption of energy Outlines actions the commission shall take to reduce the wasteful, uneconomic, inefficiency, or unnecessary consumption of energy, including the energy associated with the use of water.
  Cal. [Public Resource] Code § 25540.3; Geothermal powerplant and related facilities; application; contents; electric generating potential in excess of capacity proposed for initial construction; potential multiple facility site In addition to the information concerning the initial powerplant and related facilities proposed for construction, the application will include the amount and sources of cooling water needed at the fully developed site and the general location and design of cooling ponds, lakes, or towers.
  Cal. [Public Resource] Code § 25602; Technical assessment studies The commission shall carry out technical assessment studies on all forms of energy and energy-related problems, in order to influence federal research and development priorities and to be informed on future energy options and their impacts, including expanded use of wastewater as cooling water and other advances in powerplant cooling.
  Cal. [Water] Code § 371; Definitions. Allocation-Based Conservation Water Pricing Procuring water supplies to satisfy increments of water use in excess of the basic use allocations for the customers of the public entity, including supply or capacity contracts for water supply rights or entitlements and related energy costs for water delivery.
  Cal. [Water] Code § 522; Further Findings; reduction of energy consumption The Legislature further finds and declares that waste or unreasonable use of water imposes unnecessary and wasteful consumption of energy to deliver or furnish the water, and it is necessary, therefore, to determine the quantities of water in use throughout the state to the maximum extent that it is reasonable to do so in order to reduce that energy consumption.
  Cal. [Water] Code § 5001; Notice; necessity of filing; exception Information concerning extracting groundwater or surface water for generating electricity are exempt from submitting a "Notice of Extraction and Diversion of Water".
  Cal. [Water] Code § 90-29; Cooperation with United States, state, municipalities, districts, etc. The Nevada County Water Agency may co-operate and contract with the US, State of CA, any municipality, district, public or private corporation, or any person in the sale or acquisition of water for the purpose of conserving and transporting waters for beneficial uses and purposes, including the generation of electric energy. 
  Cal [Water] Code § 12581; Study of water development projects; considerations In studying water development projects, full consideration shall be given to all beneficial uses of the State's water resources, including irrigation, generation of electric energy, municipal and industrial consumption of water and power, repulsion of salt water, preservation and development of fish and wildlife resources, and recreational facilities.
Colorado  Colo. Rev. Stat. § 23-41-114; Colorado energy research institute-- creation Creates the CO energy research institute of the CO School of Mines. It is the duty of the Institute to maintain liaison with the state to identify important regional energy and energy-related minerals problems, including their relationship to the use of the waters of the states.
  Colo. Rev. Stat. § 40-2-123; New energy technologies- consideration by commission- incentives- demonstration projects- definitions- legislative declaration- repeal Energy is critically important to Colorado's welfare and development and its use has a profound impact on the economy and environment. In order to diversify Colorado's energy resources, attract new businesses and jobs, promote development of rural economies, minimize water use for electric generation, reduce the impact of volatile fuel prices, and improve the natural environment of the state, the general assembly finds it in the best interests of the citizens of Colorado to develop and utilize solar energy resources in increasing amounts.
Connecticut Conn. Gen. Stat. Ann. § 16a-4a; Office of Policy and Management. Duties and powers  The Office of Policy and Management shall prepare state-wide or interregional plans for the physical, social, and economic development of the state. The plan may include land use and water considerations and as well as energy capabilities and requirements.
Illinois Ill. Rev. Stat. ch.45, §147/5; Great Lakes--St. Lawrence River Basin Water Resources Compact The Great Lakes- St. Lawrence River Basin Water Resources Compact. Definition of "environmentally sound and economically feasible water conservation measures" means those measures, methods, technologies or practices for efficient water use and for reduction of water loss and waste or for reducing a withdrawal, consumptive use or diversion that, among other things, are environmentally sound, reflect best practices applicable to water sector, and consider energy impacts.
Indiana Ind. Code Ann. §14-25-15-1; Great Lakes--St. Lawrence River Basin Water Resources Compact The Great Lakes- St. Lawrence River Basin Water Resources Compact. Definition of "environmentally sound and economically feasible water conservation measures" means those measures, methods, technologies or practices for efficient water use and for reduction of water loss and waste or for reducing a withdrawal, consumptive use or diversion that, among other things, are environmentally sound, reflect best practices applicable to water sector, and consider energy impacts.
Michigan Mich. Stat. Ann § 324.34201; Great Lakes--St. Lawrence River Basin Water Resources Compact The Great Lakes- St. Lawrence River Basin Water Resources Compact. Definition of "environmentally sound and economically feasible water conservation measures" means those measures, methods, technologies or practices for efficient water use and for reduction of water loss and waste or for reducing a withdrawal, consumptive use or diversion that, among other things, are environmentally sound, reflect best practices applicable to water sector, and consider energy impacts.
Minnesota Minn. Stat. Ann. §103G.801; Great Lakes--St. Lawrence River Basin Water Resources Compact The Great Lakes- St. Lawrence River Basin Water Resources Compact. Definition of "environmentally sound and economically feasible water conservation measures" means those measures, methods, technologies or practices for efficient water use and for reduction of water loss and waste or for reducing a withdrawal, consumptive use or diversion that, among other things, are environmentally sound, reflect best practices applicable to water sector, and consider energy impacts.
New York N.Y. [Environmental Conservation] Law § 21-1001(McKinney) The Great Lakes- St. Lawrence River Basin Water Resources Compact. Definition of "environmentally sound and economically feasible water conservation measures" means those measures, methods, technologies or practices for efficient water use and for reduction of water loss and waste or for reducing a withdrawal, consumptive use or diversion that, among other things, are environmentally sound, reflect best practices applicable to water sector, and consider energy impacts.
Nevada Nev. Rev. Stat. § 533.372 Approval or rejection of application to use water to generate energy for export  Based upon the public interest and the economic welfare of the State of Nevada, the State Engineer may approve or disapprove any application of water to beneficial use or any application which contemplates a change in the place or beneficial use of water to a use involving the industrial purpose of generating energy to be exported out of this state.
Ohio Ohio Rev. Code Ann. §1522.01; Great Lakes--St. Lawrence River Basin Water Resources Compact The Great Lakes- St. Lawrence River Basin Water Resources Compact. Definition of "environmentally sound and economically feasible water conservation measures" means those measures, methods, technologies or practices for efficient water use and for reduction of water loss and waste or for reducing a withdrawal, consumptive use or diversion that, among other things, are environmentally sound, reflect best practices applicable to water sector, and consider energy impacts.
Pennsylvania Pa. Cons. Stat. Ann. tit. 32, §817.22; Enactment of compact The Great Lakes- St. Lawrence River Basin Water Resources Compact. Definition of "environmentally sound and economically feasible water conservation measures" means those measures, methods, technologies or practices for efficient water use and for reduction of water loss and waste or for reducing a withdrawal, consumptive use or diversion that, among other things, are environmentally sound, reflect best practices applicable to water sector, and consider energy impacts.
South Dakota S.D. Codified Laws Ann. § 45- 5- 21.1; Permits for energy industry use- Period for application of water to beneficial use Section does not apply to permits issued to South Dakota Conservancy District for energy industry use or permit/ right held by energy industry acquired pursuant to assignment by the director. Periods for completion of construction or application of water to beneficial use for rights transferred by the district to energy industry users shall be fixed in the instrument of transfer but may not exceed ten years from the date the contract is executed for application of water to beneficial use.
  S.D. Codified Laws Ann. §46A- 1- 71; Legislative findings regarding need for program of statewide water development and financing The Legislature finds that the proposed use of Madison formation water for widespread energy development in Wyoming presents an immediate threat to ground and surface water supplies and agricultural, domestic, environmental, and other beneficial water uses in western South Dakota.
  S.D. Codified Laws Ann. §46A- 2- 18; Acquisition of water rights by district- rights to appropriate water for energy industry use Notwithstanding any other provision of law, the district may acquire, by obtaining a permit or permits from the water management board, rights to appropriate water for energy industry use for marketing to energy industry users for such consideration and under such terms and conditions as are fixed by contract or instrument of conveyance. The district may not acquire rights to appropriate more than fifty thousand acre-feet of water for energy industry use per year.
  S.D. Codified Laws Ann. §46A- 2- 19; Transfer of water rights or permits to appropriate water for energy industry use to users- contract provisions The district may sell, grant, convey, assign, lease, or otherwise transfer perfected water rights or permits to appropriate water for energy industry use to energy industry users for such consideration and under such terms and conditions as are fixed by contract or instrument of conveyance. Such contracts shall represent the entire financial obligation for the use of water owed by an energy industry user to the State of South Dakota and no further fee, tax, or assessment shall be levied against such user except for an ad valorem tax as assessed under chapter 10-37.  
Washington Wash. Rev. Code Ann. §90.82.070; Water quality component Watershed planning under this chapter shall address water quantity in the management area by undertaking an assessment of water supply and use in the management area and developing strategies for future use. Strategies for increasing water supplies in the management area, which may include, but are not limited to, increasing water supplies through water conservation, water reuse, the use of reclaimed water, voluntary water transfers, aquifer recharge and recovery, additional water allocations, or additional water storage and water storage enhancements. The objective of these strategies is to supply water in sufficient quantities to satisfy the minimum instream flows for fish, provide water for future out-of-stream uses for water, and ensure that adequate water supplies are available for agriculture, energy production, and population and economic growth under the requirements of the state's growth management act.
West Virginia W.Va. Code § 5B-2F-2; Purpose Creates the Division of Energy as a state agency under the Department of Commerce. The division shall hold public hearings and meetings to receive public input regarding proposed energy policies and development plans. The energy policy and development plans shall address increased efficiency of energy use, traditional and alternative energy, water as a resource and a component of energy production, energy distribution systems, the siting of energy facilities, the increased development and production of new and existing domestic energy sources, increased awareness of energy use on the environment and the economy, energy infrastructure, the development and implementation of renewable, clean, technically innovative and advanced energy projects in this state.
Wisonconsin

Wis. Stat. Ann. §281.343; Great Lakes- St. Lawrence River Basin Water Resources Compact

Wis. Stat. Ann. §281.344 ;Water conservation, reporting, and supply regulation; when compact is not in effect

Wis. Stat. Ann. §281.346; Water conservation, reporting, and supply regulation; after the compact takes effect

Ratifies the Great Lakes-St. Lawrence River Basin Water Resources Compact. Definition also applies to statutes that apply when the compact is not in effect and after the compact takes effect. Definition of "environmentally sound and economically feasible water conservation measures" means those measures, methods, technologies or practices for efficient water use and for reduction of water loss and waste or for reducing a withdrawal, consumptive use or diversion that, among other things, are environmentally sound, reflect best practices applicable to water sector, and consider energy impacts.
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