Desalination eyed as US water crisis solution

Ever-more-frequent water shortages and a growing population are forcing the USA to look long and hard at how it will provide fresh water for the public and industry.

Desalination, the process of removing salt from seawater or groundwater, is certain to be part of the solution but according to the National Research Council, a gathering of academics set up to inform government policy, work must be done to reduce the environmental impact and colossal energy demands.

There are already desalination facilities in every US state but these currently generate less than 0.4% of the country's water.

If desalination is to become more than a technological niche market, says the NRC, government funding is needed and additional research should make reducing the environmental impact the top priority.

"Uncertainties about desalination's environmental impacts are currently a significant barrier to its wider use, and research on these effects, and ways to lessen them, should be the top priority," said Amy Zander, chair of the NRC committee looking at desal.

"Finding ways to lower costs should also be an objective. A coordinated research effort dedicated to these goals could make desalination a more practical option for some communities facing water shortages."

The true environmental impact of desalination remains largely unknown.

According to a report published by the NRC, existing studies suggest that desalination may be less environmentally harmful than many other ways to supplement water, such as diverting freshwater from sensitive ecosystems, but definitive conclusions cannot be made without further research.

This should look at the extent to which fish and other creatures get trapped in saltwater intake systems and seek ways to mitigate this and other impacts.

Studies also should examine the long-term ecological effects of disposing of the salt concentrate that remains after desalination in rivers or the sea, a common practice.

In addition, environmental evaluations of new desalination plants should be conducted, including ecological monitoring before and after the plant starts operating. The results should be synthesized with existing data in a national assessment that can guide future decision making, the report says.

Sam Bond




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