Solar Thermal Desalinization Shows Promise for Ag
February 25, 2014
PANOCHE WATER DISTRICT AND STATE TEST SOLAR THERMAL DESALINIZATION
Source: Excerpted from Todd Woody, The New York Times and posted By CDFA
With California facing a record-breaking drought, the spigot has gone dry for farmers that depend on long-term contracts with the federal government’s Central Valley Project to deliver cheap water from the north. Irrigation costs are expected to double or triple as growers are forced to buy water on the spot market. “Food prices are going to go up, absolutely,” said Dennis Falaschi, manager of the Panoche Water District, as he drove his pickup truck past bone-dry fields of almond trees and grapevines on an unseasonably warm day recently.
But, on a wheat field in Firebaugh, a giant solar receiver installed slowly rotates to track the sun and capture its energy. The 377-foot array, however, does not generate electricity but instead creates heat used to desalinate water.
It is part of a project developed by a San Francisco area start-up called WaterFX that is tapping an abundant, if contaminated, resource in this parched region: the billions of gallons of water that lie just below the surface. Financed by the Panoche Water District with state funds, the $1 million solar thermal desalinization plant is removing impurities from drainage water at half the cost of traditional desalinization, according to Aaron Mandell, a founder of WaterFX.
If the technology proves commercially viable — a larger plant is to be built this year — it could offer some relief to the West’s long-running water wars.
For agricultural water districts like Panoche, solar thermal desalinization promises to solve two persistent problems. One is a chronic water shortage, even in rainy years, as regulators divert water to cities and for environmental purposes, like protecting endangered fish. The other is the growing salt contamination of agricultural land that has led farmers to abandon more than 100,000 acres in the Central Valley in recent years.
During the pilot project, WaterFX produced 14,000 gallons of purified water a day. A commercial version of the plant, set to be built this year on 31 acres of land, will produce 2,200 acre-feet a year. That’s the amount of water that would cover an acre of land at a depth of one foot, or 717 million gallons. The company will store excess heat generated by the solar array in molten salt to allow the plant to operate 24 hours a day.
Mr. Mandell said WaterFX currently produces an acre-foot of water for $450. That compares to about $280 an acre-foot charged by the Central Valley Project — when water is available. This year, farmers in the Panoche district will receive no water. Last year, they received only 20 percent of their allocation, Mr. Falaschi said. In 2012, the allocation was 40 percent. Farmers elsewhere who rely on the State Water Project to irrigate 750,000 acres of farmland will also receive no water in 2014.