Ridding ocean water of salt still too costly

0 Comments | Oakland Tribune, Jul 6, 2006

DESALINATION of seawater flirts somewhere near the fringe of realistic water possibilities for California, particularly in communities near this seemingly endless source.

The problem is electricity, not water. It takes a huge amount of electricity to convert the salty water into a tasty, drinkable supply. But is a breakthrough on the horizon? Two recent reports from respected Bay Area institutions point in opposite directions.

We continue to hold out hope for desalination. A technological breakthrough would be wonderful news for California and downright historic for other arid regions of the world that dont have so many options.

The bullish news on desalination comes from the Lawrence Livermore National Laboratory. There, researchers have been experimenting with new ways to extract the salts.

To do that, the saltwater has to pass through some sort of membrane that captures the dissolved solids and allows a drinkable supply to emerge. The challenge is to come up with a membrane that is easy for the water to pass through.

The standard process for existing desalination plants is known as reverse osmosis. This process requires considerable amounts of electricity to push the water through large membranes. The Lawrence Livermore researchers, however, thought small. They came up with new carbon nanotube membranes that are no larger in dimension than a quarter. The salt was separated with one-fourth of the electricity as in the current industry standard. If this small experiment could be replicated at a large scale, Lawrence Livermore would be onto something historic.

Think of a toolbox when you think of future water solutions for the state. Everyone (particularly politicians) seem to have a favorite tool, whether it is a new dam or a low-flow toilet. Desalination can be a political compromise rather than a proven alternative. It will either be a big or small tool in the future, depending on whether that elusive technological breakthrough actually happens.

Sacramento Bee

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