Drought Spurs Surge in California Desalination, Can Solar Help?

by Karen Rubin

California’s epic drought – the worst in 500 years – is sparking a surge in desalination projects, much to the consternation of environmentalists who point to the intense energy needed to extract ocean water and desalinate it as adding to the very global warming that is producing the drought.

The state’s first project in San Diego, will be the biggest desalination plant in the Western Hemisphere when it comes online in 2016.

The $1 billion public-private project in Carlsbad is being built by Israel’s Poseidon Resources. It will pump 50 million gallons
of drinkable water out of the ocean a day, enough
water for 112,000 households. The company is also advancing another desalination project in Huntington Beach.

And that’s not all. 17 large desalination facilities are
planned along the California coast: Oceanside, Camp Pendleton, Dana Point, El Segundo, Oceano, Cambria, Monterey Bay, Santa Cruz, Moss Landing, and Pittsburg. 

Smaller desalination plants are already operating, although many operate intermittently, according to the State Water Resources Control Board.

Problems with Desalination

It’s understandable that people look to the vast ocean and see an  unlimited supply of water through desalination. But the technology comes with plenty of problems – high costs, intensive energy use and ecological damage.

Problem #1: Desalination consumes huge amounts of energy. Producing  that energy not only doubles the cost of water, it comes at a time when the state needs to cut energy use, creating a kind of Gordian knot for planners.

It takes a lot of energy to force 100 million gallons of ocean water through screens that filter out contaminants. "There are less expensive, less environmentally damaging ways to increase our water supply," Rick Wilson with Surfrider Foundation, told NPR. The group – as do many – believes conservation and water recycling are the best solutions.

But water districts have already invested in both, and although it’s helped, more water is needed to meet demand, Jeffrey Kightlinger, general manager of Southern California’s Metropolitan Water District told NPR. That’s because population has grown so much and because climate change is wreaking so much damage, he says.

Can desalination run on renewable energy?

 

California-based WaterFX thinks it has an answer. Its Aqua4  parabolic solar thermal technology is already a hit with farmers.

Most of them already conserve water by using drip irrigation instead of sprinklers, but because the water is salty once it enters the soil, they drain it into salt-tolerant wheatgrass crops, which are sold as food for cows.

"Finding a way to make it suitable for people to drink and use on the crops would be a breakthrough, a farmer told San Francisco Chronicle.

Aqua4 allows them to do that. The Chronicle explains how it works:

"Water that dribbles down from nearby hills, and through the soil after being used for irrigation, collects so much salt, selenium, boron and other minerals that it’s not fit for human consumption. The solar plant captures the runoff using a French drain-style system 6-8 feet under the crops, and sends the tainted water through pipes and tanks that heat it."

The heat is produced by huge, parabolic solar reflectors. Once heated, steam is created, which condenses the brackish water into usable liquid, separating out the minerals.

The water can then be used again for irrigation. And the minerals are so efficiently distilled, they can be processed and sold – selenium and boron for vitamin supplements and gypsum for drywall, for example.

Aqua4 can treat any kind of wastewater, drainage water, runoff, saline groundwater and industrial process water … all right on site. The resulting fresh water costs $450 per acre-foot – not much more than farmers typically pay – and about 75% less than conventional desalinated water. 

For a year, a pilot project has proved the technology works – it’s been pumping out 14,000 gallons of fresh water a day. By next year, it could expand to the point where it processes 2 million gallons of purified water a day. 

"Eventually, if this all goes where I think it can, California could wind up with so much water it’s able to export it instead of having to deal with shortages," co-founder Aaron Mandell told the San Francisco Chronicle. "What we are doing here is sustainable, scalable and affordable." 

Another startup, Wind4Water, based in Massachusetts, has developed a wind-based desalination technology. Texas has experimented with wave technology and renewable energy-powered desalination is also under development in Abu Dhabi.

Problem #2: Desalination plants cause environmental damage. One problem is that fish and  other aquatic life get sucked into water intakes. Another is that residual brine – a byproduct of the desalination process – is discharged directly into the ocean, polluting the environment.

To solve these problems, California’s State Water Board is considering various regulations.  

"We think there are less expensive, less environmentally damaging ways to increase our water supply," says Rick Wilson with Surfrider Foundation.

Problem #3: Easy water supplants conservation efforts. If citizens believe there is an unlimited supply of water, it will be hard to convince them to conserve water, and municipalities
may invest their limited resources in desalination rather than on upgrading wastewater treatment plants to be capable of recycling water.  

Corporations Saving Water

Meanwhile, corporate leaders like Adobe, Google and eBay are using simple measures that save lots of water. Adobe, for example, has cut water use 62% since 2000 just by installing low-flow faucets, waterless urinals and using drought-resistant native plants and drip-irrigation systems. Fountains at its San Jose headquarters that run on recycled groundwater have been turned off to allow that water to flow into the nearby Guadalupe River, reports The Guardian.

"Additionally, we are looking at ways to recapture rain water, reclaim our own waste water, and use recycled water (if available) from the cities where we have operations," says Adobe.

Data Centers are a big focus for driving down energy and water use. They are the biggest source of water use for eBay – which is evaluating options from installing rows of fans to passive cooling technologies. Adobe is looking at using recycled water for cooling.  

By using recycled water to irrigate plants at Google headquarters, they saved nine million gallons of water last year. Really simple things like checking for leaks can make a huge difference, they say. EBay’s smart irrigation systems respond to changes in the weather, according to The Guardian. 

Because water consumption at solar plants is also a concern, SunPower uses robots that wash solar panels – that’s cut the need for water 90%, spokeswoman Helen Kendrick told The Guardian. 

Another indication of how dire California’s situation is that wildlife officials are considering trucking 12 million hatchery-raised salmon to the ocean if enough rain doesn’t fall in March. If rivers  slow to a trickle in April and May, young salmon won’t be able to swim to the sea. 

Desalination is among many steps currently under vigorous debate in California. All options are on the table: cleaning contaminated groundwater, building wastewater recycling plants that can recharge underground reservoirs, fixing leaks in canals and community water systems, and even building new dams and surface reservoirs.

One thing is for sure. This winter was California’s warmest on record, and with temperatures climbing going forward that will only lead to more aggravated droughts.