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Research Highlights

March 2015

Electricity Needs Water: A State-by-State Assessment

Scientists model the future of water required to generate U.S. electricity

water consumption electric power industry 2095
Electric Power Water Consumption 2095. Electric power plants withdraw almost half of the freshwater supply in the United States. Thus, power generation must compete with other water needs for scarce resources in areas often affected by drought. Understanding the consumption and demands for water by the electrical power sector in the future is important as freshwater availability is challenged because of climate change. Pictured is water consumption projected through 2095 through three scenarios with different "what if" conditions. zoom Enlarge to See Full Image.

Results: The hair dryer label cautions against mixing water and electricity. But water is required to produce the electricity that heats homes, powers industry, and yes, dries hair. To understand the increasing water requirements by U.S. electric power producers, researchers at Pacific Northwest National Laboratory employed a computational model to estimate the state-by-state need through 2095.

"This detailed accounting of technologies and geographical information through the end of the century will help inform scientific and policy questions at the heart of the U.S. water-energy nexus," said co-author Dr. Mohamad Hejazi, climate researcher working at the Joint Global Change Research Institute (JGCRI), a partnership between PNNL and the University of Maryland.

Why It Matters: Currently, U.S. water requirements for electricity generation account for nearly half the total freshwater withdrawal. With a changing climate, steadily growing electricity demands and limited water supplies in many water-scarce areas poses a significant challenge. While electricity production is likely to increase in the near future, it is less certain how the U.S. electric-sector water demand will change. Some energy production technologies are less water intensive than others. This study sheds light on the interactions between the electricity and water systems, both state-wide and nationally.

Methods: In this study, PNNL researchers, working at JGCRI, used the Global Change Assessment Model (GCAM), a technologically detailed model of the economy, energy, agriculture and land use, water, and climate systems. The researchers extended the model to simulate electricity and water systems at the state level (GCAM-USA).

Under a set of seven climate scenarios, they used the model to estimate future state-level electricity generation and consumption, and their associated water withdrawals and consumption. These seven scenarios had extensive detail on the generation fuel portfolio and the cooling technology mix, with the associated water-use intensities of both.

The scenarios allowed the researchers to investigate the implications of mitigating factors that could play out in the future: socioeconomic development and growing electricity demands, cooling system transitions, adoption of water-saving technologies, climate mitigation policy, and electricity trading options on future water demands of the U.S. electric-sector. All scenarios project a decline in the future electric-sector water withdrawal through the century.

states water projections for electrical power generation 2095
Modeling estimates of the state-level electric sector water consumption under three scenarios. All assume no adoption of water-saving technologies in power plants. Green, reference scenario; yellow is the RCP4.5_NucCCS scenario which includes mitigation through nuclear and CCS technology; and red is the RCP4.5_RE scenario that includes mitigation through renewable energy systems. All scenarios project to 2095.

The climate scenarios revealed several water impacts. For instance, in areas such as the Southwest where water can be a scarce resource, the research looked at the trade-off between water withdrawal and water consumption. Drought in 2008 caused several power plants to shut down for days due to lack of cooling water. In this case, the increased use of closed loop cooling systems will mean less water withdrawal, but relatively high water consumption. And in coastal regions in California and elsewhere, regulations that require reduction in once-through cooling systems may improve conditions for marine life, but result in greater use of freshwater challenging local watersheds. These changes will also add substantial renovation costs to the power plants in those areas.

The research found that climate mitigation strategies such as nuclear power and carbon capture and storage will increase water consumption. Strategies that support renewable energy and water-saving technologies will reduce it. The study's high level of geographic and technology detail provides a platform to address scientific and policy relevant and emerging issues at the heart of the water-energy nexus.

What's Next? Interesting questions remain about the mechanisms of sectoral water competition outside the United States. These questions include incorporating desalinated water and groundwater, evaluating different climate mitigation and adaptation policies, and assessing environmental impacts of energy-sector transformation processes. Future research can expand the GCAM-USA framework to other countries and regions.


Sponsors: This research was supported by the U.S. Department of Energy's (DOE's) Office of Science through the Integrated Assessment Research Program as part of the Regional Integrated Assessment Modeling (RIAM) project. The Platform for Regional Integrated Modeling and Analysis Initiative (PRIMA), conducted under the Laboratory Directed Research and Development Program at PNNL, also provided capabilities. JGCRI is a partnership between PNNL and the University of Maryland. 

Research Team: Lu Liu, Mohamad Hejazi, Pralit Patel, Page Kyle, Yuyu Zhou, Leon Clarke and James Edmonds, PNNL; Evan Davies, University of Alberta.

Research Area: Climate & Earth Systems Science

Reference: Liu L, M Hejazi, P Patel, P Kyle, E Davies, Y Zhou, L Clarke, and J Edmonds. 2014. "Water Demands for Electricity Generation in the U.S.: Modeling Different Scenarios for the Water-Energy Nexus." Technological Forecasting and Social Change 94:318-334. DOI:10.1016/j.techfore.2014.11.004

Related highlight: Water for Power

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Water and Power

Water is used in many ways for generating power in the United States. Water's primary role is to provide cooling for more than 90 percent of U.S. power plants. In supporting roles, water is also used in drilling and mining, fuel transportation, and emissions control. Water use takes two forms: withdrawal and consumption. Withdrawal is the process of removing water from the water source, which may or may not get returned to the source after use. Water that is lost in the process of making power, through evaporation or use in closed loop power plants, qualifies as consumption.