Water and energy systems constitute the foundation for modern civilization around the world. Without water, societies never get started, and without power, it is difficult for economies to grow. At the same time, modern power generating equipment needs water for cooling and processes, creating an interdependency between water and energy infrastructure and potential for conflict over water resources. As a result, the Energy-Water Nexus is a topic of great interest and discussion among federal policy-making and regulatory entities; private and public sector water and electric utilities; state and local governments, and many supporting technical, educational, professional associations. At the nexus of water and energy exists a host of societal issues, policy and regulatory debates, environmental concerns (local and global), technological challenges, and economic impacts that must be balanced or optimized to permit ongoing economic development for all (NETL, 2008).
Estimates indicate that from 1950 to 1980, demands for water increased steadily across all sectors, with 1980 being the peak water use year. However, since 1980, withdrawals declined. Despite the overall decline, the built environment demands continued increase. This of course ignore the natural environment demands, which may play a large part in the economic stability of some regions. Unlike water demands, the total US power consumption continues to climb as a result of population increases. The US Census Bureau (2004) projects that the national population will increase from 282 million people in 2000 to 420 million by 2050. The Energy Information Administration (EIA) project, assuming the latest Census Bureau projections in its reference case, the U.S. population to grow by about 70 million in the next 25 years and electricity demand to grow by approximately 50 percent (EIA, 2006). More people, means more power. More power means more water for cooling unless all new power is solar or wind, something highly unlikely. On the current track, which suggests and expansion of fossil fuel plants, the power sector may be highly vulnerable to changes in water resources, especially those that are already occurring, and are likely to intensify, as result of climatic changes (Vorosmarty et al 2000, Bates et al 2008, Dai 2010, NETL 2010d).
Adding to the challenge is that planning by drinking water, wastewater, and electric utilities occurs separately and is not integrated. In the US, the energy sector uses 39% of the water withdrawals on an annual basis for cooling, immediately behind the 40% used by agriculture (Lisk et al, 2012; GAO, 2012). Urban demands (12.6% of water use – Sanders and Webber, 2012) require clean water supplies to protect public health. Both sectors need to manage supplies for changes in demands throughout the year, but because they are planned for and managed separately, their production and use are often at the expense of the environment (NREL, 2011). This separate planning occurs for a multitude of reasons, including tradition, regulatory limitations, ease, location, limited organizational resources, governance structure, and mandated requirements. However, as demands for limited water resources continue to grow among all sectors, and as pressures on financial resources increase, there are benefits and synergies that can be realized from integrated planning for both water and electric utilities and for their respective stakeholders and communities. The link between energy and water is important – water efficiency can provide a large savings for consumers and the utility. Reduced energy consumptions benefits the consumer – but should always be considered as one of the first steps (Gould, 2011). As a result, there is a need to move toward long-term, integrated processes, in which these resources are recognized as all being interconnected (NREL, 2011). Only then can the challenges to fully to optimize management of water resources for all purposes be identified (Scanlon et al 2005).
The lack of planning creates the situation where competition for water between agriculture, power and urban uses will reach a tipping point (or beyond in many basins) as an expected increase in thermoelectric capacity by electric utilities, and an increasing prevalence of droughts could induce possible water shortages. By 2025, Ciferno (2009) suggests the most vulnerable areas for water shortages are fast growing areas: Charlotte, NC, Chicago, IL, Queens, NY, Atlanta, GA, Dallas, TX; Houston, TX, San Antonio, TX, and San Francisco. Immediately behind these areas are Denver, CO; Las Vegas, NV; St Paul MN, and Portland OR (Ciferno,2009). Hightower (2009) notes that virtually all the states west of the Mississippi and many southeastern states will experience regional or statewide water shortages in the coming decade (2010-2020). The South and the Southwest are particularly vulnerable (Glassman, et al, 2011) because they rely on air conditioning to provide a comfortable environment, which requires more power for a growing population, requiring more water for cooling power plants.
These projections come with recent experience that is likely to foretell the future. The south, Texas and parts of the west have had repeated drought periods in recent history. During the summer and fall of 2007, a serious drought affected the southeastern United States. River flows decreased, and water levels in lakes and reservoirs dropped. In some cases, water levels were so low that power production at some power plants had to be stopped or reduced (Kimmel and Veil, 2009). The Tennessee Valley Authority (TVA) Gallatin Fossil Plant is not permitted to discharge water used for cooling back into the Cumberland River due to thermal pollution (water > 90 F) (WSMV Nashville 2007; Kimmel and Veil, 2009; NETL 2009c). Nuclear and coal-fired plants within the TVA system were forced to shut down some reactors (e.g., the Browns Ferry facility in August 2007) and curtail operations at others. This problem has not been limited to the 2007 drought in the southeastern United States. A similar situation occurred in August 2006 along the Mississippi River (Exelon Quad Cities Illinois plant). Other plants in Illinois and some in Minnesota were also affected (Union of Concerned Scientists 2007). The production of gas from oil shale and biofuels has exacerbated the issues in the Plains states (Kansas, Oklahoma, Texas), Upper Rocky Mountains, and the Ohio River Valley (Hightower, 2009; Kimmel and Veil, 2009). DOE (2006) specifically identifies where new power plants have been opposed because of potential negative impacts on water supplies (Tucson Citizen, 2002; Reno-Gazette Journal, 2005; U.S. Water News Online, 2002 and 2003; Curlee, 2003). Recent droughts and emerging limitations of water resources have many states, including Texas, South Dakota, Wisconsin, and Tennessee, scrambling to develop water use priorities for different water use sectors (Clean Air Task Force, 2004a; Milwaukee Journal Sentinel, 2005; GAO, 2003; Curlee, 2003; Hoffman, 2004; U.S. Water News Online, 2003)
So what is currently happening? Current legislation is mostly silent on the power-water nexus. This is not to say that little is being done. A number of federal agencies are actively involved with the power-water nexus, including DOE, via NETL, and NREL, NOAA, USEPA via water Wise and Energy Star, BLM though management of land and water resources in the west, USDA and Department of the Interior/USGS which inventories water supplies. However, DOE (2006) noted that collaboration on energy and water resource planning is needed among federal, regional, and state agencies as well as with industry and other stakeholders. GAO (2012a) notes that the growth in water and energy demands is occurring at a time when the nation’s supplies are stressed by a growing population, a variety of new and changing uses, and environmental challenges such as climate change, but none of the involved agencies consistently or strategically collaborate on to ensure a harmonized approach to energy and water resource planning.
Effective integrated energy and water policy planning will require identifying the individual and cumulative impacts that power plants have on water resources and the vulnerabilities of specific power plants to changes in water resources (Wilkinson 2007, Scott and Pasqualetti 2010;Stillwell et al 2011; Kenney and Wilkinson 2012). From a systems perspective, a sustainable society is one that has in place the institutional, social and informational mechanisms to keep in check the feedback loops that cause exponential population growth and natural capital depletion. A sustainable world is not a rigid one, where population or productivity is held constant. Yet sustainability does require rules, laws and social constraints that are recognized and adhered to by all (Meadows, 2005). Integrated planning implies removing silos, working collaboratively, and using resources wisely. It implies using the combined intelligence of multiple parties in the planning and fulfillment of goals. It implies linking a vision, priorities, people, and institutions into a flexible system of evaluation and decision-making. In other words, leadership.
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