Adherents clamoring for more irrigation water for California farms have gained a powerful ally: the sun. It’s helping desalinate brackish water in one important Central California farm community.
An Israeli company has set up its desalination plant on property owned by the 44,000-acre Panoche Water and Drainage District in Firebaugh in western Fresno County. In the pilot phase the unit has cleaned and returned to the distribution system as much as 80 gallons per minute irrigation water of a purer quality than farmers can obtain from their own wells or from district canals. Instead of using conventional power sources the unit relies on solar power.
The installation is located near an area that collects drainage runoff from several large farms in the water district. It has been standard practice for years for farms in the area to install drainage tiles below ground to allow the irrigation water which both carries and collects crop-damaging salts, boron and other minerals to drain away from crop roots.
The simplest explanation of the cleansing process compares it to boiling water on the kitchen stove. The steam carries the salt and other minerals away, leaving a purified liquid. Instead of a gas or electric burner, a special vegetable oil heated by the magnified rays of the sun does the job at Panoche, utilizing a shiny 525-foot long parabolic collector that looks a little like an inverted wiener-shaped umbrella.
Once the water has been cleansed of damaging salts it is added to canal water the district receives from the San Luis Reservoir and redistributes it to its farmer members.
Operation of the plant for the past year has been considered experimental, but Dennis Falaschi, manager of the water and drainage district, says his members are ready to enter a long-term commitment with manufacturer WaterFX to expand the facility. He expects the larger unit to cleanse and return to the system 300,000 acre feet of water annually.
Relying on the sun to provide the heat needed to purify the salty water puts the Panoche unit in a class separate from any of the dozen and a half desalination plants operating or planned for other California locations. Some operate by forcing brackish sea water through a membrane to which the salt clings. Power requirements for the established facilities are enormous.
California can be a water exporter?
Falaschi estimates that treated water can be achieved through the expanded facility at a cost of $325 per acre foot. In this extremely water-short year water is selling for as much as $3,500 per acre foot in some locations.
Operation of the unit produces a residue of salt, boron, and a few other solids, all of which are saleable on the food and plant nutrition market. Mining these promises to be profitable.
Most of the other desalination plants planned or already operating in California hug the coast, where heat from the sun is not as consistent or even as intense, as it is in the warm Central Valley, especially in the spring through early fall months. Utilizing the sun’s rays for power generation has become widely popular among the area’s homeowners.
Suppliers of the unit at Panoche suggest that duplicating its expanded version and applying the concept in other parts of the state has the potential of establishing California as a water exporter.
Falaschi’s view is more conservative. “We’re dealing only with replacement water, not a solution to our state’s water needs. We must work with others to fix the system that takes water from agriculture and uses it for other purposes. We have been forced to spend money to replace water that has been taken from us.”
For Central Valley farmers, who depend on the sun for crop development, finding their silent partner so willing to help with the water issue might be serendipity at its best.