Solar Water Purification Technology Recycles Ag Runoff

A water recycling pilot project in California’s drought-plagued agricultural heartland is looking for customers among local cities to fund a $25 million to $30 million expansion that would break ground next year and scale up its current 14,000-gallons-per-day production to 2 million gallons a day as early as next summer.

The water treatment plant, owned and operated by the San Francisco-area company WaterFX and funded by the state, captures heat from the sun with curved mirrors stretching 377 feet that evaporate and condense pure H2O from dirty, salty groundwater and agricultural drainage. The $1 million pilot plant, founded by technology entrepreneur Aaron Mandell, started about a year ago.

“If proven successful and cost-effective, the process could go really big-time,” said Dennis Falaschi, manager of the Panoche Drainage District, which is utilizing the system. Still, he cautioned this "is not a process that’s going to solve California’s water woes.” For now, it’s “supplementary” and currently provides a “very small” percentage of the valley’s fresh water, he said. On Monday, the Panoche Valley baked in 102-degree heat, and the residents haven't seen signicant rainfall in three years, Falaschi said.

WaterFX’s method produces water at about $450 per acre-foot (an acre-foot is about 326,000 gallons), and its economic viability could largely depend on how much water will be available in coming years.

A comparable process of producing fresh water from seawater, called reverse osmosis, is used in a few cities in California but uses much more electricity, can harm fish populations and costs anywhere from $750 to $2,000 per acre-foot. A federal water management system called the Central Valley Project provides farmers with water for $280 per acre-foot when it’s available. This year, farmers in Panoche Valley didn’t receive a single drop of that water due to the crisis. Many farmers across California have rationed water to their most valuable crops like grapes while letting others like tomatoes lie fallow, which could drive up food prices across the country. Some farmers were forced to buy water from spot markets at around $3,500 per acre-foot.

“We need to be able to market the water. We have to find a buyer,” Falaschi said. “Agriculture can’t afford that [$450 per acre-foot]. We need to find a local city to buy it.”

According to Mandell, the water treatment plant is a good idea no matter the rainfall, because "climate change has provided a new normal." The Panoche Valley could save the fresh water one year and decide to sell the water produced to another community the next year.

"The reality is these types of projects really don’t depend on the drought," he said. "Regardless of the drought conditions, we’re trying to produce water that has 100 percent reliability... Extended dry periods like we’re seeing now are going to become more and more normal."

Dry and wet years in California are pretty unpredictable, said Doug Parker, director of the California Institute for Water Resources at the University of California. This year the state is getting two-thirds of its water from underground and one-third from surface water like rivers, a flip-flop from recent years when two-thirds of water consumption came from surface waters.

“I think the WaterFX technology is good and will have some application in some places,” Parker said. However, he said he thinks widespread solutions to California’s water woes are more about preserving and using water efficiently than innovating ways to produce water.

Meanwhile, Mandell is asking others to adopt his water purification method and help improve it, seeing his company's role as installing and operating future modules.

"We want to promote the use of this technology, and we intend to put everything we’ve developed into the public domain," he said.