U.S. GAO on mutually dependent water and energy

[ This post contains excerpts from a Government Accountability Office on the interdependency of water and energy.  Mutual dependencies make the essential systems that keep us alive more fragile, since disruption in one can cause shortages or failures in related systems.

Alice Friedemann   www.energyskeptic.com  author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”]

USGAO. September 2012. ENERGY-WATER NEXUS. Coordinated Federal Approach Needed to Better Manage Energy and Water Tradeoffs GAO-12-880. United States Government Accountability Office.

Report to the Ranking Member, Committee on Science, Space, and Technology, House of Representatives

Excerpts from this 38 page report (rearranged, sometimes reworded/shortened):

Water and energy are inextricably linked and mutually dependent, with each affecting the other’s availability.  Water is needed for energy development and generation, and energy is required to supply, use, and treat drinking water and wastewater. Water and energy are also essential to our health, quality of life, and economic growth, and consequently the demand for both of these resources continues to rise.

Water is increasingly in demand to meet the needs of the public, farms, and industries, and for recreation and wildlife; and while freshwater flows abundantly in many of our nation’s lakes, rivers, and streams, it is a dwindling resource in many parts of the country.

Similarly, energy is increasingly in demand to support manufacturing and transportation, among other things. As the demand for water increases, the demand for energy is similarly expected to grow. While the growth rate in energy consumption in the United States has slowed over time, overall consumption continues to rise, with estimates from the Department of Energy’s (DOE) Energy Information Administration (EIA) showing an expected growth of 10% between 2010 and 2035. To help meet this increased energy demand, domestic energy production is rising, along with its associated water usage. According to the Congressional Research Service, the energy sector has been the fastest growing water consumer in the United States in recent years and is projected to account for 85% of the growth in domestic water consumption between 2005 and 2030. This increase in water use associated with energy development is being driven, in part, by rising energy demand, increased development of domestic energy, and shifts to more water-intense energy sources and technologies.

Since 2009, GAO has issued five reports on the interdependencies between energy and water.  GAO’s work has demonstrated that energy and water planning are generally “stove-piped, with decisions about one resource made without considering impacts to the other resource.

Water for Oil and Gas

A considerable amount of water is used to extract oil and natural gas, which often produce wastewater— known as “produced water”—that must be managed or treated.

Water for Thermoelectric power plants

Thermoelectric power plants use a fuel source—for example, coal, natural gas, nuclear material such as uranium, or the sun—to boil water to produce steam. The steam turns a turbine connected to a generator to produce electricity.  And even biofuel refineries require cooling.

A considerable amount of water is used to cool thermoelectric power plants.  Some of this is consumed – no longer available because it’s evaporated. Thermoelectric power (and biofuels) are the second largest consumers of water in the U.S. (11%).

Thermoelectric was the largest in terms of water withdrawals – 49% — from oceans, rivers, lakes, and aquifers to cool power plants down, though this water becomes available afterwards.

Energy for thermoelectric power plants

Advanced cooling technologies, such as dry cooling that use air rather than water for cooling, can reduce water use at thermoelectric power plants. But these technologies may incur “energy penalties” since the energy required to power the cooling systems may reduce the plant’s net energy production to a greater extent than traditional cooling systems, potentially leading to higher electricity prices. In addition, advanced cooling technologies can have capital costs that are up to 4 times as expensive as traditional cooling systems, and they may operate less efficiently in dry, arid locations, among other concerns.

Water for Biofuels

A considerable amount of water is used to grow feedstocks to produce biofuels. The impact of increased biofuel production on water resources will depend on where the feedstock is grown and whether or not irrigation is required.  Biofuels, also require the use of large amounts of fertilizers and pesticides to grow the feedstock which may negatively affect water quality.  Water is also used in the fermentation, distillation, and cooling processes of converting the feedstock into biofuel.

Water consumption refers to the portion of the water withdrawn that is no longer available to be returned to a water source, such as when it has evaporated.  Irrigation was the largest consumer, at approximately 74% (Elcock 2010). Biofuel production (and thermoelectric power) are the second largest consumers of water in the U.S. consuming 11% of water.

Biofuels were the second largest cause of water withdrawals (after thermoelectric plants) with irrigation accounting for 31%.

Some of the largest increases in corn acres for biofuel production are projected to occur in the Northern Plains, which relies on irrigation and is already water-constrained. Parts of this region draw heavily from the Ogallala Aquifer, where water withdrawals for agriculture and other uses are already greater than the natural recharge rate from precipitation.

Even in typically water-rich states, such as Iowa, concerns have arisen over the effects of increased biofuel production, and research is needed to assess the hydrology and quality of a state’s aquifers to help ensure the state is on a path to sustainable biofuel production.

Conversion of cellulosic feedstocks is expected to use less water compared with conventional feedstocks in the long run. Since commercial-scale production has not yet been demonstrated; any estimates on water use by cellulosic biorefineries are simply guesses at this time. Focusing only on certain potential benefits of new technologies without understanding the full impacts of such technologies can have unintended consequences.

Water for Concentrating Solar Power Plants

Concentrating solar power plants that use wet cooling could significantly increase water demand, consuming up to twice as much water per unit of electricity produced as traditional fossil fuel power plants. Concerns with concentrating solar power plants are particularly acute in the Southwest—a prime location for siting these facilities because of abundant sunshine—because water supplies in the region are already limited.

According to DOE officials, concentrating solar power plants are generally being built with dry cooling systems in the Southwest to minimize water use. However, according to a 2009 DOE report to Congress, while dry cooling can eliminate over 90% of the water consumed by wet-cooled concentrating solar power plants, wet cooling is preferred to minimize cost and maximize efficiency.

Water for Oil Shale

Oil shale development would also require a great deal of water if commercial production of this energy source becomes economically feasible in the future.  Production of oil shale requires the heating of rock containing solid organic matter to between 650 and 1000 degrees Fahrenheit and injecting water into the formation to stimulate the oil to flow. To date, there has been no commercial production of oil shale resources, in part, because the energy requirements to heat the rock and the water needed to stimulate the flow of oil make the process too costly to compete with other sources of oil. Current known processes for producing oil from oil shale deposits, however, are not economically feasible—the oil costs more to produce than it could be sold for.

Water for Carbon Capture and Sequestration (CCS)

Research to determine how new technologies will affect the energy-water nexus has not been conducted to demonstrate the effects of these technologies at commercial scales. For example, according to many specialists we spoke with and some studies we reviewed, implementing CCS technologies would consume large amounts of freshwater and affect the quality of nearby water supplies.

Energy for water supply

Pumping water accounts for 80 to 90 percent of the energy used to supply drinking water in some systems. Moving water over hills and long distances can increase the level of energy consumption significantly.

Providing drinking water and wastewater services to an urban environment involves extracting, moving, and treating water. Energy plays a crucial role throughout this life cycle. Energy is needed to:

  • extract raw water from the source—such as lakes, rivers, and underground aquifers
  • convey it to water facilities
  • treat and distribute as drinking water to customers
  • circulate, pressurize, and heat water for use inside households and businesses
  • water lawns, etc.
  • convey wastewater to treatment facilities
  • treat the wastewater
  • discharge the treated effluent into a receiving body of water.

 

The price customers are charged for the water they consume does not reflect all of the costs required to extract, treat, and supply the water. Therefore, consumers may be unaware of the true costs of water and more likely to waste it, which in turn leads to unnecessary energy use to produce more water.

Reducing the energy required to move and treat water is hindered by the costs of retrofitting water treatment facilities and other obstacles, as we discussed in our March 2011 report on energy for water supply. For example, the use of variable frequency drives at water treatment facilities, which allow operators to accommodate variations in water flows and run pumps at lower speeds, can reduce energy use by 5 to 50% or more. However, installing the drives can be cost prohibitive, and they are not necessarily well suited in all instances, such as when water flow is relatively constant.

Biofuels – reducing water consumption

[The GAO neglects to note that conservation tillage means less material to make biofuels out of below].

Agricultural conservation practices can reduce the potential effects of increased biofuel feedstock cultivation on water resources, but there are barriers to their widespread adoption. For example, conservation tillage practices—such as “no-till” systems or reduced tillage systems, where the previous year’s crop residues are left on the fields and new crops are planted directly into these residues—can help reduce soil erosion. Research conducted by USDA has shown a substantial reduction in cropland erosion since 1985, when incentives were put in place to encourage the adoption of conservation tillage practices. However, many farmers do not have the expertise or training to implement certain agricultural practices, and some practices may be less suited for some places. For example, farmers usually need a year or more of experience with reduced tillage before they can achieve the same crop yields they had with conventional tillage, and the amount of agricultural residue that can be removed varies by region and even by farm. Consequently, a national policy encouraging additional biofuel production would benefit from continued education and outreach provided by the federal government to help farmers better understand the advantages of adopting such conservation practices.

Climate change, population growth, competition for resources

According to the literature we reviewed and specialists we spoke with, climate change, population growth, increased competition for resources, and demographic shifts are expected to exacerbate the challenges associated with water and energy supply and demand, and shifts in any of these areas are expected to increase demand for both of these resources.

Moreover, the effects of climate change are expected to vary by location and, in some locations, are expected to increase demand for both energy and water resources while simultaneously decreasing water supplies. According to the literature we reviewed, higher temperatures from climate change are expected to lead to additional demand for air conditioning and, therefore, electricity. This increased electricity demand will, in turn, lead to increases in water consumption associated with power generation. However, at the same time, climate change is expected to change the quantity and reliability of water supplies so that less water may be available in some regions, thereby resulting in reduced water supplies for use by the energy sector, according to some specialists we spoke with. In addition, as one specialist told us, higher temperatures from climate change will produce more evaporation from water reservoirs and other bodies of water, such as the Great Lakes, which can produce significant water losses.

Problems associated with climate change are only exacerbated by population growth and competition for water resources. More people will consume more water, increasing the municipal sector’s water demand. To meet these increasing demands, some states, especially those in areas that are already water stressed, such as Texas, have pursued alternative sources of water, such as desalinated water, which are more energy- intensive than traditional groundwater and surface water supplies. In addition, because of a warmer climate and decreased precipitation, farmers are expected to withdraw more water to irrigate crops. Minimum water levels are also necessary for other uses, such as recreation and industry, as well as to support wildlife and maintain ecosystems. Demographic shifts, such as migration to the hot, arid Southwest, could place additional demands on both energy and water supplies.

References (not all of them)

Elcock, D., “Future U.S. Water Consumption: The Role of Energy Production,” Journal of the American Water Resources Association, vol. 46, no. 3 (2010): 447-460.

GAO, Energy-Water Nexus: Improvements to Federal Water Use Data Would Increase Understanding of Trends in Power Plant Water Use, GAO-10-23 (Washington, D.C.: Oct. 16, 2009)

GAO, Energy-Water Nexus: Many Uncertainties Remain about National and Regional Effects of Increased Biofuel Production on Water Resources, GAO-10-116 (Washington, D.C.: Nov. 30, 2009)

GAO, Energy-Water Nexus: Amount of Energy Needed to Supply, Use, and Treat Water Is Location-Specific and Can Be Reduced by Certain Technologies and Approaches, GAO-11-225 (Washington, D.C.: Mar. 23, 2011)

GAO, Energy-Water Nexus: A Better and Coordinated Understanding of Water Resources Could Help Mitigate the Impacts of Potential Oil Shale Development, GAO-11-35 (Washington, D.C.: Oct. 29, 2010)

GAO, Energy-Water Nexus: Information on the Quantity, Quality, and Management of Water Produced during Oil and Gas Production, GAO-12-156 (Washington, D.C.: Jan. 9, 2012).

 

 

 

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