“Water, water everywhere, nor any drop to drink…” Samuel Taylor Coleridge, 1798, in the “Rime of the Ancient Mariner.”
The reality confronting millions of Californians as they cope with yet another lengthy episode in a seemingly endless series of droughts is that – like Coleridge’s mariner – this state has billions of acre feet of water clearly visible every day in the form of the Pacific Ocean and its many bays and estuaries.
But that’s briny salt water, containing an array of minerals that make it almost as inaccessible today as it was to that parched, fictitious sailor of 200 years ago.
But it doesn’t have to stay that way. As the price of water goes up, desalinating Pacific waters becomes ever more enticing and it will become more so if the price of taking salts and other impurities out of salt water falls. In short, if the rising price of fresh water ever comes to match a falling cost for purified sea water, expect desalination to begin on a large scale in California.
It appears things are moving that way now. Over the winter, the Metropolitan Water District of Southern California – largest urban water district in the state – paid Sacramento Valley rice farmers an average of $694 per acre foot of water for 115,000 acre feet to be sent south via the state Water Project. For some farmers, selling water is now more profitable than growing crops.
This sounds like a lot to pay for one acre foot, the amount needed to cover an acre one foot deep and about the quantity used by two typical urban families in the course of a year. But at that price, water costs still costs only about one-fifth of a cent per gallon. Well water, by comparison, averages about $293 per acre foot.
Meanwhile, ideas for new methods of desalinating water arrive frequently at the state Department of Water Resources, where analyst Michael Ross checks to see which might have real promise.
“The cost of desalination will come down,” Ross says. “The price of other water is coming up, as we can see from the Met’s purchase. Right now I have a basket-full of proposed processes on my desk.”
Traditional desalination via the process of reverse osmosis (RO) will vastly increase later this year, when Massachusetts-based Poseidon Water opens a $1 billion facility at Carlsbad in northern San Diego County. The plant will make 48,000 acre feet yearly, about 7 percent of San Diego County’s supply, at a cost of about $2,200 per acre foot. A smaller RO plant opened four years ago in Sand City, near Monterey. Santa Barbara plans to reopen a similar plant that was mothballed for years.
But some believe reverse osmosis, which uses a series of membranes to filter sea water, is too expensive.
One idea Ross has reviewed comes from a Texas firm called Salt of the Earth Energy, which would use water from perforated plastic pipes eight to 15 feet beneath the ocean floor, mixing gases and chemicals into sea water from which ocean-bottom silt has filtered almost all marine life. The process would also produce industrial chemicals like phosphates, carbonates and hydroxides, helping bring down the cost of the water produced.
The firm’s consultant, James Torres of Rancho Cucamonga, says the high end of water cost using this process would be $650 per acre foot, less than the Met is now paying for some of its supply.
“This idea is at a proving stage,” said the DWR’s Ross. A test facility is planned along the Gulf Coast of Texas and if it proves promising, the method could solve many current problems with RO, including the fact only half the water RO plants take in eventually becomes potable; the rest is returned to the sea as heavy brine harmful to marine life.
“Our process uses 90 percent of the intake,” said Torres. “And we’ll use only about half the power of an RO plant.”
Another possibly promising technology called “Zero Discharge” is currently being tested in the Panoche Water and Drainage District in Central California, using solar power to evaporate and then collect water from irrigation discharge, with about a 93 percent recovery rate.
Which means drought has not brought despair. Instead, it’s spurring an inventiveness that may soon put the lie to the Rime of the Ancient Mariner.
