Desalination Ready for Prime Time?

Associated Press/Gregory Bull

lawrence fisher writes about business for The New York Times and other publications.

Published January 19, 2016.

There is a genre of survival story in which desperate shipwrecked sailors are reduced to drinking seawater. In the fifth year of an historic drought, the driest and hottest period ever measured in the state, California certainly qualifies as desperate. So perhaps it's not surprising that San Diego County is about to bring online the largest seawater desalination plant in the country and that a slew of other desal projects in California are in the pipeline.

The conventional wisdom about desalination has run from iffy to Hail Mary. Building a desal plant is a big, multiyear undertaking subject to all the political hurdles, legal challenges and cost overruns common to major infrastructure projects. Removing the salt from the water uses a lot of energy, which will certainly cost a lot, and, depending on the energy source, may contribute to the global climate change that, ironically, has exacerbated California's water predicament. Moreover, sucking in seawater and disposing of the concentrated brine left from producing potable water may threaten marine life. Indeed, many environmentalists loathe desalination with a passion previously reserved for dams, strip mines and nuclear power.

In its simplest form, desalination has been around since ancient times, when sailors would boil seawater and collect the water vapor as it condensed. In fact, such thermal desalination is still viable where there is a virtually free source of waste heat, like the boilers of power plants and aircraft carriers.

But most big desal projects today use a process called "reverse osmosis," which involves pumping seawater at great pressure through a slightly porous membrane; it's the same technology used in making de-alcoholized wine. And, as with many technologies, reverse osmosis’ efficiency has grown as the engineers improve the process. Energy consumption -- and therefore cost -- has declined considerably in recent years, making it a more viable alternative in coastal areas where the fresh water supply is not reliable.


"We're in a pretty desperate situation," Burnett said. "We've reviewed a huge number of options and concluded desalination has to be part of the mix, in spite of the economic and environmental downside."


Desalination is a major source of drinking water in the Middle East (at least in the driest, richest parts); Israel gets 55 percent of its water from desal in cities, about one-quarter nationwide. Drought-prone Australia has also been a major adopter of desal – though five of its six plants are currently mothballed (perhaps prematurely) because the rains returned after an awful drought.

The United States has lagged in adopting desal, in no small part because much of the country is blessed with rivers and lakes, gigantic aquifers and ample rainfall. Desal also has a troubled history here, most notably with the plant in Tampa Bay, Fla. (the nation's largest), which opened five years late, cost $40 million more than expected and was unable to supply the full 25 million gallons a day that was originally promised. A smaller plant in Santa Barbara, Calif., was mothballed in 1992, just months after it went live, when a previous drought ended. It is now being restarted.

A Last Resort?

Jason Burnett, the mayor of Carmel-by-the-Sea, is about the last person you would expect to find stumping for desalination. A son of two marine biologists, he is a scion of the Packard family (as in Hewlett-Packard), whose fortune built the Monterey Bay Aquarium and finances countless other ocean health initiatives. He considers himself a lifelong environmentalist, pledged to reducing global warming. But he’s like those guys in the lifeboat.

"We're in a pretty desperate situation," Burnett said. "We've reviewed a huge number of options and concluded desalination has to be part of the mix, in spite of the economic and environmental downside."

The Monterey Peninsula, which includes Monterey, Carmel and Pacific Grove, has long sourced most of its water from the Carmel River, but discovered a few years ago that it had no permit to do so. The state, moreover, wouldn’t grandfather continuing use because the river is a spawning ground for endangered steelhead trout. The governments of these deep-pocket communities explored every conceivable alternative, including harnessing icebergs and towing them down the coast, and filling huge balloons with water up north and floating them south. Desalination was the only viable one.

Reverse osmosis filters in the Carlsbad plant


"We already conserve as well or better than anyone in the state," Burnett said, noting that the peninsula's 100,000 residents use an average of just 55 gallons per day per household. A 2011 study estimated that the average California household used more than 360 gallons (though this figure has fallen during the drought).

Burnett ticked off the drawbacks. "You have to figure out how you're getting the source water; you have to figure out what to do with the brine. It uses a lot of energy. Even on an operating basis, if someone gave you a large desalination plant for free, it would not be economical to run" under ordinary conditions. Including plant amortization, Monterey's water will cost about $2,000 an acre-foot (about 326,000 gallons), ten times the national average.

Burnett said Monterey was going to great lengths to mitigate the effects on marine life. Instead of gulping seawater directly, which tends to kill fish, eggs and larvae, the plant will take in 2,000 gallons a minute through pipes buried 200 feet under the ocean floor; the sand above will serve as a filter and diffuser, thereby only minimally disrupting marine reproduction.

The doubly salty brine left over from desalination will be diluted by mixing it with a nearby storm sewer outfall and using pressurized diffusers to spread the saline discharge, which would otherwise tend to linger on the sea floor to the detriment of the local ecology. This feature alone will add $10 million to the project's cost, Burnett said.

The Monterey desal plant is expected to take about two years to build, with at least another year after that to complete the permitting process. So it may not begin delivering water to customers for several years.

Planning for the Next Drought

Four hundred miles to the south in Carlsbad, Calif., a plant yielding more desalinated water than all the U.S. desal facilities combined will come online next year. It has been 12 years in the making, born in reaction not to the current drought, but the previous one – or the one before that.

"Our project in Carlsbad sort of grew out of the concerns of the 1990s, but it's really about more than a given drought event," explained Carlos Riva, chief executive of Poseidon Water, a water infrastructure specialist based in Boston that is building the plant. "San Diego County came to a decision to diversify its water supply; the county was 90 percent dependent on imported water. They wanted to gain more control over their water supply by sourcing it locally."

Carlsbad will be the largest desalination plant in the Western Hemisphere, providing 10 million gallons of desalinated seawater per day when it first comes online and ultimately up to 50 million per day. (The largest in the world is, no surprise, in Saudi Arabia; that plant has the capacity to desalinate some 260 million gallons a day.) The $1 billion Carlsbad project will produce enough drinking water to serve 300,000 people, providing 7 percent of San Diego County's total supply by 2020. Though Poseidon Water is financing construction, water users will, of course, pay for the plant through increases in their water bills, expected to run to $5-7 a month. But that difference may narrow because the price of water currently imported from overtaxed rivers far to the north and east has been rising every year.

"Just to permit something like this and get it to the point where you can raise the financing was quite a complicated and difficult exercise," Riva said. "Because this was the first large-scale desalination plant coming down the pike, the regulators didn't have any experience to draw on. Plus, we had a lot of resistance from the environmental movement; there were 12 legal challenges." All of those challenges were beaten back.

Poseidon is now in the late stages of developing a similar-sized plant 60 miles up the coast in Huntington Beach, which is scheduled to be operational by 2018. Riva said that he believed there could be several more like it along the California coast and that the start-to-finish time could drop to as little as three years.

"The depiction of what desalination does to the environment has been painted as very severe," Riva noted. "But when people see how low impact and low visibility the Carlsbad facility is, opinion will change."

Counting the Costs

There's really no question that desalination plants are costly and have some adverse impact on the environment. But that has been true of every water supply project since the Roman aqueducts.

The tortuous history of southern California development is inextricably tied to water imported from elsewhere, as brilliantly depicted in Roman Polanski's 1974 neo-noir film, Chinatown. Bringing water south from the Sacramento, San Joaquin and Colorado rivers consumes a great deal of energy, loses a great deal of water to evaporation and has turned major waterways into concrete-lined canals. But, then, pumping water from aquifers and damming rivers to create reservoirs generate their own unpleasant externalities.

Courtesy of Poseidon Water
Carlsbad desalination plant under construction, September 2015
"People talk [disparagingly] about toilet-to-tap, but the way we've urbanized the world, everything is toilet-to-tap. Everybody is downstream."

It takes 3,460 kilowatts per acre-foot to push water from northern California to San Diego County. The Carlsbad project will use about 30 percent more energy to desalinate ocean water and deliver it to households, according to Poseidon's report to the Department of Water Resources. That's an acceptable difference, especially in light of the diminishing availability of water as northern California suffers from its own drought and demand for Colorado River water outstrips supply.

Perhaps a better benchmark is Israel, which is not awash in cheap energy and has a level of environmental awareness similar to the United States. "We sell desalinated seawater to the government in Israel for around $900 per acre-foot," said Udi Tirosh, business development manager for IDE Technologies, the Israeli company that is supplying the reverse osmosis system for Carlsbad. "That's less than you pay in California for just transferring the water from north to south. When desal is there, you don't have to wait for rain or snowpack on the mountain. During the drought 10 years ago, … San Diego just did not get water."

Tirosh said the environmental impact of desalination had been modest. "We are measuring the brine disposal effect on sea fauna and flora. … We see that there is an influence, but it is confined to 300 to 400 feet around the head. And even within the region, it's not a death zone. It's more an area where species that can survive the higher concentration are flourishing and other species avoid it."

The environmental groups that fought the Carlsbad plant did not offer a lot of specifics to flesh out their objections. Sara Aminzadeh, the executive director of the California Coastkeeper Alliance, told The New Yorker: "It's just not a good option from a cost and energy standpoint. Desalination may seem like a panacea, but it's the worst deal out there."

To be fair, there aren't a lot of specifics to be had. Other than the studies that the desal companies have done themselves, there is not much data on the environmental effects of the process. "While we have a number of desalination plants around the world," explained Heather Cooley, co-director of the Pacific Institute, a research organization focusing on sustainability, "this is not an issue that's been well monitored. Some are old; some are in regions that don't have the environmental sensitivities we have in California. Also, the impacts are site-specific."

The source of the energy used to desalinate seawater is another concern. Burning climate-warming fossil fuels to generate freshwater amounts to robbing Peter to pay Paul. In Australia, the climate change dilemma was eased by purchasing renewable energy offsets equivalent to the power consumed by the desalination plants. "So far, none of the plants in California have proposed to do that," Cooley said.

Consider the Alternative

In the digital era, humanity has grown accustomed to exponential gains in productivity even as costs fall. But, unfortunately, water does not obey the magical laws of silicon chips. The power consumption of desalination has indeed come down; reverse osmosis now uses about one-fourth the energy it required in the 1970s. But no one sees equivalent gains on the horizon. There's no getting around the reality that pumping seawater through a membrane fine enough to separate the salt requires a lot of energy.

"The misleading thing about desalination is people see it as a silver bullet," pointed out David Henderson, managing director of XPV Capital, a Toronto-based private equity firm specializing in water technology. "Water is heavy, and this is a downside to desal that people don't think about. If you're in Los Angeles, right on the ocean, it makes some kind of sense. But most of your water isn't consumed there; it's inland, in farm regions. It's eight pounds to the gallon; whenever you move something very heavy, it takes a lot of energy, and it becomes very expensive."

Henderson said reuse makes more sense in many locations. "If you can recycle that same drop of water on the same location, over and over again, that is your big winner," he said. "People talk [disparagingly] about toilet-to-tap, but the way we've urbanized the world, everything is toilet-to-tap. Everybody is downstream."

A Sensible Mix

One of the more irritating habits of good financial advisors is that they almost always recommend a diversified portfolio of low-cost mutual funds, when what you really want is to buy some hot tech stock that will make you financially independent. Investing in our water future is a bit like that. While it's tempting to look to a tech fix like reverse-osmosis desalination as the answer, the real solution is a broad portfolio that includes conservation, reuse and smarter use as well as desal.

In the 20th century, we didn't have to think about water, explained Charles Fishman in his book The Big Thirst. But no more. Even the famously moist Pacific Northwest had to ration water last summer because an uncommonly warm winter decimated the mountain snowpack. And though early rains this fall have caused flooding in southern California, no one is predicting the return of easy water.

"Smart water managers now think in portfolio terms," Fishman said. "The old fat way was, 'I've got reservoirs, I'm fine,' or 'I've got a river, that's my source of water, I'm fine.' There's no water manager thinking that way now."

Desalination has earned a place in a diversified water supply portfolio. In the annals of seawater desalination, the plant in Perth, Australia, is often held up as the right way, in contrast to the wrong way at the troubled Tampa Bay plant. The Perth facility was finished in less than two years, and its power consumption was offset by the utility's investment in renewable energy. It supplies about 40 million gallons a day, 17 percent of the water used in a territory bigger than Western Europe.

But the most interesting aspect of Perth's success is that a second installation of comparable size was never constructed. "In the course of building that plant in two years, they actually taught their customers to save 40 million gallons a day," Fishman said. "They eliminated the need for Phase 2 through conservation." Which makes for a sturdy maxim: the best desalination plant is the one you never need to build.

California has already done much to reduce water use through a mixture of voluntary efforts, warnings, fines, and what The New York Times called "a culture of nagging." But it should be kept in mind that the cheapest gallon of water is almost always on the demand side of the equation, where water-sparing technology, cost-based market pricing and more of that California-style nagging could make a huge difference.