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Tuesday, February 8, 2011

Desalination: Technologies, Use, and Congressional Issues

Nicole T. Carter
Specialist in Natural Resources Policy

In the United States, desalination technologies are increasingly used for municipal and industrial water supplies and reclamation of contaminated supplies. At issue for Congress is the federal role in desalination research, demonstration and full-scale facilities, and regulatory requirements.

Wide adoption of desalination for supplying municipal drinking water, especially from seawater, remains constrained by financial, environmental, regulatory, and other factors. Desalination processes generally treat seawater or brackish water to produce a stream of freshwater, and a separate, saltier stream of water that has to be disposed (often called waste concentrate). Desalination’s attractions are that it can create a new source of freshwater from otherwise unusable waters, and that this source may be more dependable than freshwater sources that rely on annual or multi-year precipitation, runoff, and recharge rates. Many states (most notably Florida, California, and Texas) and cities are actively researching and investigating the feasibility of large-scale desalination plants for municipal water supplies.

Coastal communities are increasingly considering desalinating seawater or estuarine water, while interior communities are looking to brackish aquifers. Some communities and industries are opting to treat contaminated water supplies with desalination technologies (e.g., membrane separation) to meet disposal requirements or to reuse the water (e.g., saline waters from oil and gas development). Others use desalination technologies for obtaining high-quality water for industrial processes.

Desalination and its different applications, however, come with their own risks and concerns. Although the costs of desalination dropped steadily in recent decades, making desalinated water more competitive with other supply augmentation options, the declining trend may not continue if energy costs rise. Electricity expenses vary from one-third to one-half of the operating cost of many desalination facilities. Improving energy efficiency would decrease the cost uncertainties associated with adopting desalination technologies. 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, there are few federal health and environmental guidelines, regulations, and policies specific to desalination as a municipal water supply source. This creates uncertainty regarding the cost and time required for regulatory compliance. Research and public education may help to resolve some uncertainties, develop methods to mitigate impacts, reduce the costs of desalination, and improve public understanding of the risks.

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, have been responsible for planning, testing, building, and operating desalination facilities, similar to their responsibility for freshwater treatment for municipal drinking water supplies. Bills in the 111
th Congress (e.g., H.R. 88, H.R. 469, H.R. 1145, S. 1462, S. 1731, S. 1733, and P.L. 111-11) represented a range of federal authorizations for desalination research and its coordination, demonstration and full-scale facilities, and planning and financing. While interest in desalination persists among some Members of the 112th Congress, efforts to expand federal activities and investment may face greater opposition in the near term due to the domestic fiscal climate and differing views on federal roles and priorities.

Date of Report: January 24, 2011
Number of Pages: 14
Order Number: R40477
Price: $29.95

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