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Is Mining Seawater the Answer to Drought?

Posted by Christina B. Farnsworth

May 7, 2014 11:35:00 AM

Charles Meyer Desalination Plant

Santa Barbara, Calif., Charles Meyer Desalination Plant built in 1991, used for three months and idle ever since. Drought may force its return to action.

 

We need water more than oil. We are 70 percent water, every single one of us, and we need to stay hydrated to that level. We may finally be entering an age predicted by president John F Kennedy. The 21st century may be the time it became common for people to mine salt water into potable water.

Mining and transforming water may become as commonplace as oil and natural gas. The difference may be that rather than doing desalination on a large scale without considering the consequences, that we are thinking about how to do it with the least damage to the environment and the least energy use.

Every time U.S. coastal communities experience long-lasting drought, they look to the sea for drinking water solutions. A 2008 report suggests that the best and most ecological and economical response to drought is conservation, though the report states that desalination has its place..

Of course, drought is a global problem. And particularly for the thirsty, it is always a surprise to see a desert on the edge of a huge humanly-undrinkable body of water. Some call the attempt to siphon and drink seawater as putting a straw into the sea. On a human scale, those straws look pretty big and can suck in sealife, some thing that multi-national desalination companies are addressing.

Santa Barbara, population 89,000, is watching its reservoir go dry and expects it has just a year or so to do something. Recently, the city announced plans to reopen its desalination facility built during California’s last severe drought in 1991 and then mothballed after only three months of use. Heavy rains saved the day.

Santa Barbara views desalination as a last-ditch costly way of producing potable water and reports that it will cost $20 million “in technological upgrades” to reactivate its $34 million existing plant. $20 million spent to get water for 89,000 people sounds expensive but actually works out to about $225 per resident. Many people spend that amount buying bottled water in a year.

Back in 1991, the Santa Barbara facility had woo people into trying the not-now-saltwater. It tasted OK, but a little flat. There are naturally occurring minerals in most drinking water that contribute to flavor. I remember being served water produced by its desalination plant back in 1991 when drought was severe throughout the state and people were tasked with saving water. Water-restrictions in Southern California were so severe that guests would bring water to parties so that the hosts would not end up using more water than they were allowed (there were heavy fines for overuse). Guests often brought their gallons to the bathroom where it would be used for flushing. When household size changed, homeowners had to prove the additional residents with the water utility so that they could buy more water at lower rates.

With the return of rain, water restrictions ended and water conservation went by the wayside; people started flushing toilets with some regularity again and Santa Barbara closed its Charles Meyer Desalination Plant. The plant closed because water gleaned from nature was much less expensive to deliver to residents. Among the reasons the plant can’t just re-open is that once mothballed, Santa Barbara sold off parts to a Saudi Arabian company. The guts of the plant became a time capsule complete with computers that use floppy disks. Thus not only does equipment need to be updated, but also some of it is just gone and needs to be purchased and installed. Estimates are that the effort could take two years. The plant is walled off behind a gate near what Santa Barbara calls its Funk Zone located between the Pacific and Highway 101.

Removing salt from water is not quick, and it’s not cheap. The chart below is from UC Davis Center for Watershed Sciences. It shows the range of costs for various forms of water treatment

Seawater desalination is the most costly. In areas where desalination is common, a problem that often develops is what to do with the salt removed. And an interesting consideration is that not all water needs to be salt free. In the gilded age when huge mansions (sometimes called cottages) were built along both coasts, the houses often had two plumbing systems serving residents and visitors. Baths had hot and cold running saltwater in addition to potable water taps because taking saltwater baths was therapeutic.   

Santa Barbara is not the only California city looking at resurrecting desalination. A Los Angeles Times article from February reports that “In the last decade, proposals for more than 20 desalting plants have been discussed up and down the coast. But even with construction about to begin on the nation’s largest seawater desalination facility, 35 miles north of San Diego” that it is doubtful the California dream of providing the state’s water from the sea “will ever be fully realized.” The plant is in Carlsbad.

Even without access to seawater, California needs and uses a lot of water. California’s population makes it larger in population than the entire country of Canada.

UC Berkeley resource economics professor emeritus Henry Vaux, Jr, said of the desalination plant, “While this Poseidon adventure may work out, I don’t look for a lot of that.” The professor contributed to a 2008 Natural Resource Council report entitled Desalination: A National Perspective (the link is a 300+page pdf).

Report conclusions include that  “Recent advances in technology have made removing salt from seawater and groundwater a realistic option for increasing water supplies in some parts of the U.S., and desalination will likely have a niche in meeting the nation's future water needs.”

In general, “Over 97 percent of the Earth's water—seawater and brackish groundwater—is too salty to use for drinking water or agriculture. Interest in desalination has grown in the United States as some regions face water shortages and contention over existing freshwater supplies. Though desalination still generates less than 0.4 percent of the water used in the U.S., the nation's capacity to desalinate water grew by around 40 percent between 2000 and 2005, and plants now exist in every state. Most use a method called reverse osmosis, which pushes water through a membrane to separate out most of the salts.”

The report expressed concerns “about the environmental impacts of desalination.” The report said more research is needed but, “Limited studies suggest that desalination MAYbe less environmentally harmful than many other ways to supplement water—such as diverting freshwater from sensitive ecosystems.”

The report called for researchers to investigate whether and which fish and other creatures would be trapped and harmed in saltwater intake systems. It also called for studies to determine long-term ecological effects of disposing of the salt concentrate remaining after desalination. It called for environmental monitoring both before and after plants opened in order to determine effects.   

The report also “raised concerns about greenhouse gases because desalination uses large amounts of energy. Seawater reverse osmosis uses about 10 times more energy than traditional treatment of surface water, for example, and in most cases uses more energy than other ways of augmenting water supplies.  Researchers should investigate ways to integrate alternative energy sources—such as the sun, wind, or tides—in order to lower emissions from desalination, the report says.” Salt or sea water reverse osmosis is often referred to as SWRO. And readers, the study quoted was released in 2008? Have these statistics changed? 

Doubtless addressing the report’s concerns are part of what Santa Barbara would be doing to upgrade and restart its existing plant. The San Diego plant cost $34 million dollars when first built in the 1990s.  According to the LA Times, the Carlsbad plant north of San Diego, called the Poseidon Resources plant, will cost $954 million financed with $781 million in tax-exempt construction bonds sold by the IDE Technologies, the international company that will operate Poseidon and the public water utility. The rest of the money is coming from private investors “who anticipate a return of about 13 percent.”

CS_example2

At $2,000 an acre foot, its purified water “will cost San Diego County Water Authority more than twice what it pays the Metropolitan Water District of Southern California for supplies from Northern California and the Colorado River.” Over a 30-year contract, “San Diego County water ratepayers will pay between $3 and $4 billion for the desalted water, which is expected to provide no more than a tenth of their overall supply.” It is worth noting that the lower prices from other places may not last long as the Colorado River is over-subscribed, as experts say, and has insufficient water to serve all desired users. Northern California needs its own water and is not thrilled with serving its water to its southern neighbors.

Water resources are often public utilities. IDE’s Poseidon is an international corporation. Consumers nationwide decry their public utilities becoming private entities. The initial cost of the water will be $2,000 an acre foot. An acre-foot is the amount of water needed to cover an acre of land of foot deep and equals 325,851.429 U.S. gallons of water.

Typically, a family of four uses half of one acre foot a year. $100 a month or more water bills are not uncommon. Just think about the water bill doubling. On the other hand, we can not live without water. Physically each one of us is about 70 percent somewhat salty water.

A New York Times feature about the plant quotes “David Moore, a managing director of Clean Energy Capital, financial advisers to the San diego County Authority, said the water authority had ‘made the call that over time this water is going to more affordable than other sources.”

IDE Americas Inc. designed the plant and will operate it when its completed in 2016. IDE is a subsidiary of the Israeli firm, IDE TechnologiesIDE Technologies describes itself as “Your Water Partners.” It designs, builds and operates some of the globe’s largest desalination plants. These include plants in China and India as well as the largest in the U.S., the Carlsbad one that will serve San Diego. In describing its Sorek plant in Israel, the company says its innovative design uses a vertical arrangement of 16-inch membranes that result in a reduced footprint. The plant also “utilizes IDE’s proprietary Pressure Center Design, Double Line Intake and ERS (Energy Recovery System) for increased efficiency and reduced energy consumption.”

The company also claims “Environmental responsibility” by minimizing marine, shoreline and land impacts “thanks to pipe jacking of long and large diameter pipelines, smart structural design and sludge treatment for reduced energy and chemical consumption.”

For the Carlsbad plant. IDE says it is using an “innovative pretreatment phase, resulting in higher efficiency, reduced energy consumption and high quality water.

So readers, what do you think? We already live with electric plants and oil refineries. Will desalination plants become part of out new normal? 

California is the nation's fruit basket. Desalination is also being used to filter brackish agricultural runoff in the Cambria Community Services District, so desalination is not limited to ocean communties. Are their other brackish waters that would benefit from desalination?


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