The past few months have highlighted a lively debate in California as to who has a right to use the dwindling reserves of freshwater. Agriculture is repeatedly called out as the largest water user, comprising up to 80% of the state’s water use every year, and therefore the target of many water conservationists and environmentalists who want to bring change to California.
The issue is a complex one as California is one of the nation’s leading agricultural states, producing a variety of crops including 80% of the world’s almonds and over 95% of the nation’s artichokes, apricots, kiwis, and plums. The Central Valley’s naturally arid climate is home to fertile soil for growing crops but comes at the high cost of importing water from the Sierra Nevada Range when there is water available from the Bureau of Reclamation, or scrambling to find another source when the yearly allocation cannot be met. Without a steady water supply for this industry, we could expect higher food prices and the loss of thousands of jobs in the Central Valley. But what if there were a sustainable way to produce water for agriculture onsite, without depleting any freshwater sources?
There is an estimated 1 million acre-feet of untapped freshwater potential sitting just below the surface in California’s Central Valley alone. Instead of being put to use, this saline water is sitting in tile drains in drainage fields that are growing every year and creating land that is unusable for natural vegetation and wildlife. As it is, this water is non-potable due to high salt levels, but with the proper treatment this wastewater can be turned into a replenishable source of freshwater.
Naturally occurring mineral salts are picked up in small quantities by freshwater as it is transported to agriculture through the Central Valley Project and the State Water Project. When crops are irrigated, they soak up the freshwater and leave behind concentrated levels of salts and minerals that then need to be drained. Salinity levels have become a major problem for Central Valley farmers who can no longer discharge irrigation drainage into the San Joaquin River due to the impact on migratory birds and other wildlife as well as contamination of drinking water in the Bay Delta. Instead, most farmers rely on drainage fields and salt-tolerant crops to soak up some of the excess water. But with recent climate change issues drying up most of the state’s yearly precipitation, wouldn’t it be better if this water were put back to use instead?
The HydroRevolutionSM plant coming to the Panoche Water and Drainage District in 2016 will be able to produce up to 5,000 acre-feet of water per year for the district without tapping into existing freshwater reserves. How is this possible? The key ingredients are saltwater and sun.
The HydroRevolution solar desalination plant uses agricultural drainage water as its source, taking the excess concentrated brine leftover from crops and removing the salts to create freshwater. The Aqua4 technology is a concentrated solar still which uses energy from the sun to heat and evaporate freshwater from the source water and effectively separate the two. The system has over a 90% recovery rate and is capable of achieving zero liquid discharge with further solids treatment.
Without sustainable treatment, irrigation drainage water builds up and is discharged into tile drains or river systems. This can come at a high price to the environment, to farmers with land at stake, and to everyone else facing mandatory water cutbacks in California. The goal of HydroRevolution is to recycle this wasted water source and create a truly sustainable source of freshwater that benefits local communities as well as the environment.