This article discusses the need for new technologies to address emerging energy and water challenges. The demand for both energy and water is expected to grow with growth in global economy and population. Therefore, there is a need to minimize future conflicts between energy and water development and to foster more reliable and sustainable use of these two very important natural resources. Several renewable energy technologies and alternative cooling approaches for thermoelectric power plants exist that could reduce water consumption for electric power generation. Improving dry, hybrid, and other alternative cooling technologies and carbon sequestration approaches could help lower future water consumption and reduce the water footprint of power plants. Likewise, research to address the issues that are limiting the implementation of low-water-use renewable energy technologies could accelerate their use, reducing both water consumption and carbon emissions. Any major scale-up of alternative transportation fuels must consider approaches that use less fresh water than current methods, and must improve water use efficiency in mining, processing, and refining future fuel resources.
Civilization relies on two basic commodities: water and energy. Without both of them in ample supply, all else fails. Sometimes the public can forget, though, that water and energy very much rely on each other.
Water is an integral part of energy development, production, and generation. Water is used directly in hydroelectric power generation and is used extensively for thermoelectric power plant cooling and air emissions control. Water is also used extensively in energy-resource extraction, refining, and processing, as well as for energy resource transportation. Therefore, as global energy consumption continues to increase, as much as 50 percent by 2030, so will the demand for water supplies and resources to support this growth. This will place the energy sector into greater competition with other water users for already limited fresh water resources in many regions of the world. This competition for water resources will likely impact both regional energy and water reliability. The U.S. Department of Energy published a report, Energy Demands on Water Resources: Report to Congress on the Interdependency of Energy and Water, early in 2007 that discussed the issues of the interdependencies between energy and water. Today, concerns over energy and water reliability are being recognized worldwide by government officials, energy and water managers, and the scientific community.
The World Economic Forum published a report in early 2009. The report, Energy Vision Update 2009, Thirsty Energy: Water and Energy in the 21st Century, discussed concerns about water demands for energy and potential global impacts that could occur on energy availability, reliability, and security.
In September 2010, the World Energy Council published its report Water for Energy, and among its findings observed that as developing nations move toward more robust economies, they will increase their demand for water to support energy development. This development alone promises to add significantly to the strain on the world's water supply.
As nations try to balance the demands and availability of water resources to support human health and economic development in the coming decades, it is clear that the water footprint, like the carbon footprint, will become an increasingly critical factor to consider in addressing reliable and sustainable energy development worldwide.
A number of institutions, including the U.S. Department of Energy and ASME, are directing efforts to meet some of the looming challenges of the near future.
Overall growth in consumption of power is not the only force spreading the energy sector's water footprint. Current efforts and policies in many developed regions are to improve energy security by increasing the use of domestic energy supplies. Ideas put forward as possible solutions include more reliance on electric power for transportation because generating electricity is less dependent on a single fuel source. Various countries are looking at domestic alternatives for transportation fuels, including biofuels, oil shale, oil sands, coal-to-liquids, hydrogen, and development of natural gas supplies from gas shales.
At the same time, concerns over climate change have raised calls for limiting carbon dioxide and other greenhouse gas emissions, and for carbon sequestration.
All these options have significant water needs and will intensify competition for already limited fresh water resources in many regions.
What's more, some plans to reduce the consumption of water for energy purposes may backfire. For example, the Environmental Protection Agency may modify the Clean Water Act Section 316b regulations addressing the withdrawal of cooling water for industries and especially power plants. The changes could force many power plants to move toward closed-loop cooling towers rather than use once-through cooling. While the move to closed-loop cooling is intended to limit the ecological and environmental concerns of cooling systems and will reduce overall water withdrawals, the move could more than double the overall water consumption of a typical power plant.
Consumption in this case refers to the water that passes a once-through system and is not returned to its source. About 200 gallons per megawatt-hour are lost to advanced evaporation of the hot water from the surface of the receiving body. Of course, the water is not truly lost, because it returns to the hydrologic cycle as vapor, but it is not available for immediate use downstream.
A plant with cooling towers consumes about 400 to 500 gallons per megawatt-hour due to evaporation. This includes all water losses for the plant for cooling. There might be a little more water use for coal scrubbing for air emission issues, but 95 percent of the water use in a power plant is for cooling.
Many areas of the world are faced with growing limitations on water resources. They are affected by competing demands for agriculture, domestic uses, and reductions in surface water flows because of climate changes. Meeting increased water consumption needs of the energy sector in such places could be difficult.
What we are seeing is increasing growth of water use for agriculture—essentially to grow crops for increasing populations and to feed changes in diet that are moving toward more meat in developing countries. Estimates are for 20 to 40 percent more water demand for agriculture.
As developing countries move toward economic growth and bigger populations, we are seeing growth in need for domestic water supplies, as much as another 20 to 40 percent growth in water demand.
It is estimated that climate change could cause up to a 25 percent reduction in surface water flows in the mid-latitude areas of the globe, which include the southern United States, southern Europe, northern Africa, the Mideast, India, China, Argentina, southern Africa, southeast Asia, Australia, and New Zealand. These include many of the major regions of the world experiencing the greatest economic and population growth.
Water use by the energy sector is expected to grow by 30 to 100 percent globally.
So that is a lot of new water needs when the water supply will likely fall by a quarter in many areas.
in 2005, the U.S. Congress funded the Department of Energy to prepare a report to identify and quantify emerging energy and water challenges and interdependencies, and to conduct a series of regional workshops to identify the science and technology needed to address and reduce the identified emerging energy and water challenges. Both efforts were coordinated for the DOE by Sandia National Laboratories with the support of the other U.S. national laboratories. This is the genesis of the 2007 report, Energy Demands on Water Resources. The report and related information are available on the Sandia Web site at www.sandia.gov/energy-water.
According to the DOE's report to Congress, over 50 percent of current daily water withdrawals in the U.S. and about 25 percent of all current daily non-agricultural fresh water consumption are for energy-related uses. As the population and economy of the U.S. grow, the demand for both energy and water are also expected to grow. While the water needs to meet the growth for electric power generation and transportation fuels production will depend on the type and number of power plants built, cooling technologies used, air and carbon emission requirements, and the type and quantity of alternative fuels used, the report estimated that water consumption by the energy sector could grow by a factor of three to four by 2035. That is an increase from about 4.3 billion gallons of water per day in 1995 (the last time there was any water consumption data collected) to between 12 billion and 15 billion gallons a day by 2035. Recent studies by the EPA support this general range of expected increases, which would make the energy sector the largest non-agricultural water consumption sector in the U.S.
This projected growth in water demand for energy generation and development over the next two decades will occur at a time when the nation's fresh water supplies are becoming increasingly stressed. These water issues were summarized in a U.S. General Accountability Office report on water availability: “National water availability and use has not been comprehensively assessed in 25 years, but current trends indicate that demands on the nation's supplies are growing. In particular, the nation's capacity for storing surface water is limited and groundwater is being depleted. At the same time, growing population and pressures to keep water in stream for fisheries and the environment places new demands on the freshwater supply. The potential effects of climate change also create uncertainty about future water availability and use.”
ASME Weighs In on the Energy-Water Connection
ASME's Energy-Water Nexus Interdisciplinary Council is a new initiative, formed in November 2010, that seeks to expedite the development of technological solutions that reduce the consumption of energy and water.
The economies of the world use water to mine, refine, and convert energy resources, and they also use energy to collect, treat, and distribute fresh water. Thus, the energy-water nexus covers a broad array of activities and technologies including desalination, power plant cooling, energy directly from water, water and wastewater treatment, water reuse, mining, and biofuel production.
The Energy-Water Nexus Interdisciplinary Council was formed by the Knowledge and Community Sector's Board on Technical Knowledge Dissemination to identify and develop market-relevant knowledge dissemination products and services for the global engineering community.
ASME members and other professionals interested in joining this new council can contact Raj Manchanda at (212) 591-7789 or ManchandaR@asme.org.
The General Accountability Office conducted a survey in 2003 of state water managers. The results, published under the title Fresh Water Supply: State's Views of How Federal Agencies Could Help Them Meet the Challenges of Expected Shortages, presented a general, nationwide concern about future water shortages by 2015 under average water supply conditions. Droughts in several regions across the U.S. from 2005 through 2008 drew even more attention to these growing regional water issues. The data in the map above, taken from the GAO report, suggest that water supply problems are no longer just a concern for the traditionally arid western United States, but have become a national issue.
While the DOE's 2007 report to Congress focused on identifying emerging U.S. energy and water interdependencies, challenges, and concerns, the regional workshops were organized to look at energy and water needs from a broad spectrum of disciplines, and to identify research efforts needed to minimize future conflicts between energy and water development and foster more reliable and sustainable use of these two very important natural resources. More than 500 participants representing federal, state, local, and tribal agencies, water and energy managers, water and energy utilities and industrial associations, environmental groups, technology developers, and academic institutions from across the U.S. participated in the workshops.
A short overview and summary of the energy research needs and directions suggested by the workshops were published by Sandia as SAND2007-1349C, Overview of Energy-Water Interdependencies and the Emerging Demands on Water Resources. Three major directions for research and development emerged from the workshops:
Reducing fresh water use in electric power and transportation fuels development. Several renewable energy technologies and alternative cooling approaches for thermoelectric power plants exist that could reduce water consumption for electric power generation. Improving dry, hybrid, and other alternative cooling technologies and carbon sequestration approaches would lower future water consumption and reduce the water footprint of power plants. Likewise, research to address the issues—such as electric grid integration, cost, and dispatchability—that are limiting the implementation of low-water-use renewable energy technologies could accelerate their use, reducing both water consumption and carbon emissions, important system-level operational requirements. Any major scale-up of alternative transportation fuels must consider approaches that use less fresh water than current methods, and must improve water use efficiency in growing, mining, processing, and refining future fuel resources.
Developing materials and water treatment approaches to enable non-traditional water use in energy generation and refining. Reuse of waste water and use of non-traditional water, including seawater, brackish ground water, and produced water, could be increased to meet water demands in many sectors. New water treatment technologies will be needed that can meet the water quality requirements at much lower energy use. Improvements in materials that minimize fouling would reduce the need for higher-quality waters, significantly expanding opportunities to replace fresh water with lower-quality waters. A wide range of technology improvements in such areas as organics removal, bacterial treatment and disinfection, reduction of membrane fouling, salt removal, and concentrate management and reuse could make possible significant reductions in energy use in water treatment and pumping, and also accelerate the use of non-traditional water resources by the energy sector.
Improving water assessment, and energy and water systems analysis and decision tools. Compounding the uncertainty of available water supplies is a lack of data on water consumption. Without water consumption data it is impossible to accurately determine resources available for use. Improved water data collection, better water monitoring and sensors, and improved assessment of non-traditional water resources are needed to effectively quantify our water resources. Also, improved decision support tools and system analysis approaches are needed to help communities and regions better address emerging demands on natural resources—energy, water, land, and environment—and challenges of availability. Tying improved water availability data with decision support and planning tools would improve collaboration on energy and water planning, and support system-level solutions that can in turn improve energy reliability and reduce fresh water consumption.
for the past several years ASME has been looking at emerging water issues and these impacts on associated energy concerns. In 2008, ASME's Center for Research and Technology Development published the ASME Water Management Technology Vision and Roadmap. One of the activities identified in the Roadmap was for ASME to conduct a series of best management practices workshops.
The center established a Research Committee on Water Management Technology, and in 2010 published the ASME Water Management Technology Best Management Practices and Innovations for the Process Industries. Copies of the Roadmap and Practices and Innovations may be downloaded from the Research Committee's Web site, http://committees.asme.org/K&C/TCOB/BRTD/WMT/Accomplishments.cfm.
Various ASME technical divisions—including the Basic Engineering, Energy Conversion, Environmental and Transportation, and Manufacturing Technology Groups—represent the kind of expertise that can address the world's water-related needs. ASME's recently formed Energy-Water Nexus Interdisciplinary Council was created in an effort to draw on that expertise.
As a further effort to focus its members’ collective know-how on the issue, ASME will offer a special energy/ water technical track at the International Mechanical Engineering Congress and Exposition in November. The track has been coordinated to address improvements in cooling, water reuse, water use efficiency, and use of non-traditional waters as ways to reduce the water footprint of new power plants.
As the U.S. and other nations try to balance the demands and availability of water resources to support human health and economic development in the coming decades, ASME is taking a proactive role in helping, supporting, and educating engineers and scientists to develop more efficient approaches to redesign how the built environment uses and reuses water in ways that will reduce the water footprint of energy and other sectors to support continued economic development and to maintain the sustainability of energy, water, and all other natural resources.