By early 2000, the emerging issue of climate change and green house gas emissions, the continuing and growing US reliance on imported oil and transportation fuels, and the growing environmental and ecological water quality concerns associated with water intake structures at power plants and hydroelectric dams, all came together to focus interest on changing or modifying the more traditional approaches to energy development in the US. Emerging interest in hydrogen fuels, biofuels, and other alternative transportation fuels such as coal-to-liquids were being promoted. Clean-coal, nuclear energy, and renewable energy technologies were being suggested as electric power generation alternatives to reduce carbon emissions. And the development of domestic off-shore oil resources, oil shales, oil sands, and non-traditional natural gas resources, such as coal bed methane, gas shales, and tight gas sands, were getting increased attention as a way to reduce the US dependence on imported oil and natural gas.
At that time, the water demands and water quality impacts of these new energy development approaches were not well quantified or put into context of how much these approaches would impact water use. There was little consideration given to whether regional water supplies or water infrastructure were sufficient to support these new energy supply strategies and approaches. For example, the scale-up of biofuels as proposed by some groups would require an extensive increase of irrigated agriculture to supply the fuel source, especially in some parts of the Midwest, where ground water resources were already being impacted by unsustainable ground water pumping. Similarly, the oil shale resources in the US are primarily in Colorado, Utah and Wyoming, all western states that already have water supply limitation problems that would likely be exacerbated by large-scale oil shale development. Also, regulatory changes being proposed by state and federal environmental agencies to limit the use of once-through cooling approaches were expected to drive electric power utilities to use closed-loop evaporative cooling for new power plants, which reduces water withdrawal but significantly increases water consumption, while also driving utilities away from the use of low quality seawater and river water and relying more heavily on the use of high quality fresh water resources for power plant cooling.
By 2002 it was evident to many energy professionals, developers, and utilities that these alternative energy development strategies and emerging environmental regulations and directions could cause a significant increase in water consumption by the energy sector, thus increasing competition with other sectors for regional water resources. At the same time, it was becoming evident that water supply availability in many regions of the country was becoming more limited. This was highlighted in a 2003 General Accountability Office (GAO) Report to Congress on water availability. The report summarized the emerging water issues in the US in this way:
“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.”
Figure 1 (below) shows data from a survey of state water managers conducted by the GAO and presented in their report to the US Congress that suggests a general concern by state water managers across the country of water shortages by 2015 under average water supply conditions. This information highlights the fact that water supply limitations and challenges are no longer simply a western US problem, but that shortages are being expected in many regions and that water resource availability and water stress is a national problem. Droughts in the US that spanned from 2002 to 2009 in various parts of the country, including the southwest, northeast, and southeast, focused attention and concern on the emerging water supply limitations and challenges.
Figure 1. Expected State Water Shortages by 2015 for Average Conditions in the United States
Therefore, the projected new growth in energy development in the next few decades that is focused on sustainability and environmental friendliness, and the associated major demands on water resources that it will ironically entail, will occur at a time when the nation’s fresh water supplies are becoming increasingly stressed by past water management practices and increased water demands by other water-use sectors. Thus the availability, cost, and access to water supplies needed to support energy development in the US will likely be a major driver to long-term energy cost-effectiveness, sustainability, reliability, and security.
Quantifying Energy Water Interdependencies and Concerns
The Report to Congress on Energy and Water Interdependencies was developed in 2006 for DoE by a team including Los Alamos and Sandia National Laboratories, the National Energy Technology Laboratory, and the Electric Power Research Institute in order to provide detailed technical information on the connections between energy and water. Using available data, a significant effort was undertaken to accurately quantify the range of water withdrawal and water consumption values that might be expected for a wide range of energy development technologies, options, scenarios, and strategies. Using this information, along with projected energy demand and energy supply sources proposed by the US DoE's Energy Information Administration (EIA) in projections from 2004 to 2006, they calculated water consumption by the energy sector in 2035 to grow by a factor of three or four for the recommended scenarios, increasing from about 4.3 billion gallons of water per day (BGD) in 1995 to about 12-15 BGD by 2035.
This magnitude of increase in water consumption would easily make the energy sector the largest non-agricultural water consumption sector in the US, almost doubling the expected water consumption of the domestic and commercial sectors combined. The ability of US water infrastructure to quickly expand to handle this growth in water demands for energy development was especially troubling to many water professionals, given the current water supply availability concerns outlined in the GAO report discussed earlier. Therefore, the baseline energy supply options being proposed appeared to be incongruent with water availability projections, highlighting the fact that water resource availability is not being appropriately factored into future energy development assumptions and projections. This could have major long-term energy security and reliability concerns, especially if policies are adopted that direct energy supply approaches which cannot be sustained because of the lack of adequate water resource availability. Given these evaluations, a range of improvements were suggested to help better address emerging energy and water interdependencies.
Reducing Water Demands by the Energy Sector to Enhance Energy Assurance
While the Energy Water Report to Congress was being developed, a series of regional needs-workshops were organized to look at energy and water issues and challenges from a broad spectrum of disciplines. More than 500 participants representing federal, state, local and tribal water and/or energy agencies, water and energy managers, water and energy utilities and industrial associations, environmental groups, technology developers, and academia from across the country participated in the Energy-Water workshops that took place from November 2005 through May 2006. Based on these workshops, three major national directions to address energy and water related science and technology issues were suggested. These include:
Enhance efforts to reduce 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 could lower future water consumption. Likewise, research to address the issues limiting the implementation of low water-use renewable energy technology, such as problems associated with electric grid integration, cost, and dispatchability, could accelerate its use, reducing both water consumption and carbon emissions, which are important system-level operational requirements. Finally, since virtually every alternative transportation fuel currently being considered will increase fresh water consumption, any major scale-up of alternative transportation fuels must consider approaches that reduce fresh water use and consumption and improve water use efficiency.
Develop materials and water treatment approaches to enable non-traditional water use in energy generation and refining
With growing limitations on fresh water supplies, expansion should be sought in waste water reuse and non-traditional water use, including sea water, brackish ground water, waste water, and oil and gas produced water, in order to help meet growing water demands. New water treatment technologies will be needed to meet the water quality needs at low energy requirements. Improvements in materials to reduce water quality requirements could significantly expand opportunities to replace fresh water use with the use of non-traditional waters. A wide range of improvements in organics removal, bacterial treatment and disinfection, reduction of membrane fouling, salt removal and concentrate management and reuse could significantly reduce energy use in water treatment and pumping and improve non-traditional water use in the energy sector.
Improve 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 natural resource—energy, water, land, and environment—demand and availability challenges. 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 improve energy reliability and energy security while reducing fresh water consumption.
Growing International Interest on Water Issues and Energy Security
While the interdependencies between energy and water, and the impacts on energy sustainability, reliability, and security were initiated in the US, these issues are being recognized worldwide by energy officials, energy and water managers, and the scientific community. For example, the World Economic Forum published a report in early 2009 discussing concerns about water demands for energy and the potential global impacts on energy availability and reliability. Droughts and the impacts of changing climate on precipitation and water supplies in Europe, Australia, Canada, and Asia are already impacting the development of future energy approaches, all of which are being driven in part by water use and water consumption considerations. Therefore, water footprints, like carbon footprints, are increasingly becoming a factor that must be considered for long-term sustainable, reliable, and secure energy development worldwide.
Mike Hightower is a Distinguished Member of the Technical Staff at Sandia National Laboratories in Albuquerque, New Mexico.