Nicole T. Carter
Specialist in Natural Resources Policy
In the United States, desalination and membrane technologies are increasingly used to augment municipal water supply in water-constrained and drought-prone locations, to produce high quality industrial water supplies, and to reclaim contaminated supplies. As of 2005, approximately 2,000 desalination facilities larger than 0.3 million gallons per day (MGD) were operating in the United States, with a total capacity of 1,600 MGD which represents more than 2.4% of total U.S. municipal and industrial freshwater use. At issue for Congress is what should be the federal role in supporting desalination and membrane technology research and facilities.
Desalination processes generally treat seawater or brackish water to produce a stream of freshwater, and a separate, saltier stream of water that requires disposal (often called waste concentrate). In the last decade, many states (e.g., Florida, California, and Texas) and cities have actively investigated the feasibility of large-scale municipal desalination. Coastal communities look to seawater or estuarine water, while interior communities look to brackish aquifers. The most common desalination technology in the United States is reverse osmosis, which uses permeable membranes to separate the freshwater from the saline water supply. Membrane technologies are also effective for other water treatment applications. Many communities and industries use membranes to remove contaminants from drinking water, treat contaminated water for disposal, and reuse industrial wastewater (e.g., saline waters co-produced from oil and gas development). For some applications, there are few competitive technological substitutes.
Wider adoption of desalination is constrained by financial, environmental, and regulatory issues. Although desalination costs dropped steadily in recent decades, significant further decline may not happen with existing technologies. Electricity expenses represent from one-third to one-half of the operating cost of desalination. Its energy intensity also raises concerns about the associated greenhouse gas emissions and usefulness as a climate change adaptation measure. Substantial uncertainty also remains about the technology’s environmental impacts, in particular management of the saline waste concentrate and the effect of surface water intake facilities on aquatic organisms. Moreover, desalination facilities often require a significant number of local, state, and federal approvals and permits. Many of the existing state and federal health and environmental guidelines, regulations, and policies are not specific to desalination. Because the approvals and permits fall outside normal practice, they often require more detailed and specific analysis; this can increase the time and cost for regulatory compliance.
Additional research may address some of the challenges. Some emerging technologies (e.g., forward osmosis, nanocomposite and chlorine resistant membranes) show promise for reducing costs. Support for emerging technologies and for research to address desalination’s environmental and social impacts is particularly relevant to the debate on the future level and nature of federal desalination research and related legislation (e.g., H.R. 2664, H.R. 5826; S. 1343).
To date, the federal government has been involved primarily in desalination research and development (including for military applications), some demonstration projects, and select fullscale facilities. For the most part, local governments, sometimes with state-level involvement, are responsible for planning, testing, building, and operating desalination facilities. Some states, universities, and private entities also undertake and support desalination research. While interest in desalination persists among some Members, especially as drought concerns rise, efforts to maintain or expand federal activities and investment are challenged by the domestic fiscal climate and differing views on federal roles and priorities.
Date of Report: June 12, 2012
Number of Pages: 18
Order Number: R40477
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