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Friday, June 7, 2013

Desalination and Membrane Technologies: Federal Research and Adoption Issues

Nicole T. Carter
Specialist in Natural Resources Policy

In the United States, desalination and membrane technologies increasingly augment municipal water supply, to produce high quality industrial water supplies, and to reclaim contaminated supplies (including from oil and gas development). 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 issues before the 113th Congress include how to focus federal research, at what level to support desalination research and projects, and how to provide a regulatory context that protects the environment and public health without disadvantaging the technology. H.R. 745 would authorize the extension of the Water Desalination Act, which authorizes appropriations for the main desalination research and demonstration outreach program of the Department of the Interior, from 2013 to 2018.

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 one-third to one-half of the operating cost of many desalination technologies. The energy intensity of some such technologies raises concerns about greenhouse gas emissions and the usefulness of these technologies for climate change adaptation. Concerns also remain about the technologies’ environmental impacts, such as saline waste concentrate management and disposal and the effect of surface water intake facilities on aquatic organisms. Construction of desalination facilities, like many other types of projects, often requires a significant number of local, state, and federal approvals and permits.

Emerging technologies (e.g., forward osmosis, nanocomposite and chlorine resistant membranes) show promise for reducing desalination costs. Research to support development of emerging technologies and to reduce desalination’s environmental and social impacts is particularly relevant to the debate on the future level and nature of federal desalination assistance. The federal government generally has been involved primarily in desalination research and development (including for military applications), some demonstration projects, and select full-scale 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 with drought concerns high, 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: May 30, 2013
Number of Pages: 18
Order Number: R40477
Price: $29.95

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