Sun-Powered Desalination May Run Cleaner

A university researcher may have discovered a way to make the desalination process cleaner by harnessing solar energy.

Philip Davies, of Aston’s School of Engineering and Applied Science in the U.K., "has devised a system using solar energy that could allow desalination plants to act as a sink, rather than a source of atmospheric carbon dioxide, and help to neutralize ocean acidity," Science 2.0 reported.

"In his model, magnesium chloride in waste brine is hydrolyzed by energy generated by heliostat fields to magnesium oxide, which is discharged to the ocean. Due to its alkaline nature, this subsequently neutralizes ocean acidity and gradually removes carbon dioxide through the conversion of magnesium oxide to bicarbonate, similar to ocean liming," the report said.

The approach actually increases the energy that the plant requires, according to the report. But Davies says it is offset by carbon dioxide absorption capacity.

"Desalination plants could become net absorbers (rather than net emitters) of CO2. The process proposed here comprises dewatering of brine followed by decomposition in a solar receiver using a heliostat field," Davies' study, published last month in Environmental Science: Water Research And Technology, reported.

Davies framed the system as a "win" for the environment.

“Lowering the energy required to dewater brine prior to decomposition would be a major environmental benefit. Not much energy is needed to decompose magnesium chloride in brine to magnesium oxide, which makes the use of solar energy potentially very attractive. If we could find better ways to dewater the brine this would become very energy efficient as a means of avoiding carbon dioxide," Davies said, per the news report.

He explained that the findings could become more useful with continued development.

"Since desalination is essentially about separating salt from water, perhaps these developments could eventually be used to remove water from the corrosive brine coming out of the desalination plant at relatively low energy cost," he said, per a university release.

For more information on desalination, visit Water Online's Desalination Solution Center.

http://www.wateronline.com/doc/sun-powered-desalination-may-run-cleaner-0001