Drought and Desalinization

Even as we bask in a Northern California smirr, not quite a rain, the multi-year drought that threatens to turn the Central Valley from a fruit basket to archeological site continues.  Desperate minds turn to the ocean: there’s an awful lot of water there! How to get and use it?  Desalinization has been used on naval ships for decades – potable,barely, but certainly good for showers and washing down decks.  What’s the situation of large-scale terrestrial projects?  Here’s a brief, recent, report from Grist.

Enter the ongoing construction of 17 desalination plants across the state. A $1 billion plant being built in Carlsbad, Calif., expected to be ready by 2016, will pump 50 million gallons of drinkable water out of the ocean daily — making it the largest such facility in the Western Hemisphere. Another project underway near San Francisco (a discount at only $150 million) could supply 20 million of the 750 million gallons of water guzzled daily in the Bay Area by 2020.

Desalination involves sucking up seawater and pushing it at high pressure through a series of very thin membranes, to strip away the salt and ocean gunk. Water purists (ha) know it as reverse osmosis. It’s not an ideal process, since it uses an enormous amount of energy to turn about two gallons of seawater into one gallon of potable water, plus there are the aforementioned ocean gunk leftovers, but it does keep working rain or shine.

I didn’t know so many were in progress, albeit with delays and frustrations.  Given the increase in population, even with lots of water savings, many more plants would be needed if the drought continues.

Weaning So Cal off water imported from other areas would mean building a Carlsbad-scale plant every four miles along the coast, which adds up to 25 plants just between San Diego and L.A.