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Thursday, Mar 28, 2024
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Tide To Tap

San Diego’s vaunted $1 billion desalination plant, which will make water from the Pacific Ocean drinkable, is on the verge of pumping fresh water into the county’s water system for the first time.

State officials are still reviewing whether the water meets state drinking water standards, but the plant is expected to gain their approval by the end of the month and begin its final round of tests, which includes ramping up to its maximum processing capacity of 50 million gallons per day. As part of those tests, the desalinated water will be sent to the county’s distribution system and eventually make its way to users.

It puts the Carlsbad plant about a month away from getting complete certification after nearly two decades of planning. Envisioned years before the latest drought began, water officials and advocates trumpet the plant’s ability to further diversify the county’s water supply and survive possibly dire cutbacks as the drought worsens. But the price is roughly double the cost of water imported from Northern California, due to the high energy levels required to make desalination work.

San Diego’s General Atomics patented some of the foundational reverse osmosis technology in the 1960s, but the process was more readily embraced in drier countries, such as Israel and Saudi Arabia, without many cheaper options.

Game-Changer

The Carlsbad plant will be the largest desalination plant in the Western Hemisphere and the industry is paying attention to see if its success accelerates desalination’s spread in the U.S.

“We’re looking for a big breakthrough for America to become a seawater market,” said Christopher Gasson, publisher of Global Water Intelligence (GWI).

The U.S. is the second-biggest desalination market in the world, he said, but mostly has smaller plants to process brackish water that require far less energy. GWI estimates the planned seawater desalination plants in California could produce a combined 123 million gallons per day if approved. Huntington Beach is proposing its own 50 million gallon per day plant, and Santa Barbara is reviving its long-shuttered desalination plant next year.

Israeli-based IDE Technologies built the Carlsbad plant and is recommissioning the Santa Barbara facility.

“Is it the silver bullet to answer a lot of California’s drought questions?” asked Mark Lambert, president of IDE’s U.S. subsidiary. “No, but it’s a part of the portfolio and it’s drought-resistant. It’s the equivalent of getting off of imported oil.”


Cost Concerns

Critics, however, caution that the water will be costly, increasing the average $75 monthly water bill by $5 to $7 next year, and that cheaper options such as wastewater reuse are just as viable. The City of San Diego’s Pure Water initiative, for example, will also use desalination technology but will use less energy and eventually produce even more clean water than the Carlsbad plant. The city expects to produce 83 million gallons of clean water per day by 2035, about a third of its total demand.

“We’re not fundamentally opposed to desalination,” said San Diego Coastkeeper interim Executive Director Travis Pritchard. “It has its place in the water supply world. But it’s an option of last resort. It is, by definition, the most expensive water we’re going to have.”

Water used to cool the nearby Encina Power Station will be piped into the desalination plant and sent through three main steps. First, it is pushed through concrete boxes filled with gravel, sand and coal to remove almost all solid particles. This clear, but still salty water is shoved through reverse osmosis membranes, which have pores so small most bacteria can’t pass through them. The pressure forces fresh water through the filter, while dissolved salt stays behind.

The process creates one gallon of usable water for every two gallons that come into the plant. The remaining gallon of leftover, briny water is diluted and put back into the ocean. But the clean water is not yet ready for the water supply.

“It’s too good to drink,” Lambert said. “It doesn’t have any taste in it; it’s too low in salinity.”

The Carlsbad plant will add back some mineral content and disinfect the water before piping it 10 miles east to be blended with the rest of the county’s water.

30-Year Deal

Developer Poseidon Water, which tapped IDE for construction, has a 30-year deal with the county to sell at least 15.6 billion gallons of water per year, though the county may buy up to 18 billion gallons to lower the unit price. The water will cost between $2,131 and $2,367 per acre foot of water, which equals about 326,000 gallons. That’s about twice what the county pays the Metropolitan Water District of Southern California for imported water and higher than the estimated $1,800 per acre foot from the city’s wastewater reuse project.

“I get the fact that it’s going up, but it’s still a great deal at less than a cent per gallon,” said San Diego County Water Authority board member and past chair Tom Wornham. “People may gripe, but they’ll be outside with pitchforks and torches if they don’t have water.”

The Water Authority predicted a few years ago that the desalinated water will eventually be cheaper than MWD’s water, which it said would get about 7 percent more expensive every year. That calculation was complicated in July by the Water Authority’s $188 million legal victory against MWD for overcharges in 2011 through 2014. The Authority said the overcharges could have totaled more than $2 billion over the next 45 years.

It’s no longer clear when the desalinated water will become cheaper than the imported water, according to the Water Authority, because MWD hasn’t updated its rates to comply with state law. Water Authority Chairman Mark Weston said he still anticipates MWD’s rates to increase.

‘Drought-Proof’

“The water we have (in Carlsbad) is drought-proof and under our control, south of active earthquake faults,” Weston said. “We put a higher value on that water in a qualitative sense.”

The Carlsbad plant will eventually provide 7 percent of the county’s water. Current supplies are already set to meet virtually all of next year’s demand, allowing the county to use some of its MWD water to refill the San Vicente Reservoir, which was lowered in 2012 during construction on the San Vicente Dam to double the reservoir’s capacity. The county will refill the reservoir in a year, much earlier than expected, and will cut back the amount of water it buys from MWD.

The county’s past reliance on MWD is actually what spurred the Carlsbad plant’s development. San Diego got 95 percent of its water from MWD during the 1991 drought, and suffered more than a year of severe cuts to its water supply. MWD slashed the county’s supply by 31 percent, which Wornham called a wakeup call for the region.

“The business community said, ‘Never again. Do not put us in this situation,’ ” Wornham said.

Through a combination of the desalination plant, water transfer agreements and other measures, the county plans to only get 26 percent of its water from MWD by 2020.

The added energy costs are a major point of contention with environmental critics of desalination, who say a focus on less intensive methods such as wastewater reuse should come first. The Carlsbad plant will need about 5,300 kilowatt hours of energy per acre foot of water, a third more than the roughly 3,900 kilowatt hours per acre foot it takes to pump and treat water from Northern California.

Even desalination developers are concerned about energy requirements, which have fallen in half over the past decade. Desalination plants almost entirely rely on fossil fuels, which foster climate change and the dry conditions that prompt many municipalities to turn to desalination in the first place, Paddy Padmanathan, the CEO of Saudi Arabian desalination developer ACWA Power, told the desalination industry at an annual conference in August.

“We have to break the cycle,” he said.

Energy costs can be cut even further, perhaps even 50 percent, according to Padmanathan. But that would butt up against what scientists believe is the lowest possible amount of energy required to make reverse osmosis work and advancements will come much slower than they have in the past.

Pritchard, the San Diego Coastkeeper director, said the group was concerned less about specifics of the Carlsbad plant design than about the nature of desalination itself. The danger, according to Pritchard, is the cumulative effect of desalination’s proliferation in regions that can turn to other sources of water.

“With current forecasts of climate change, we expect to experience a drier Southwest,” he said. “We expect to see the increase in energy usage to lock ourselves into a water cycle.”

Pritchard pointed to the county’s 25 percent reduction in water use over the past few months prompted by Gov. Jerry Brown’s demands for statewide cutbacks. The reductions came with minimal real costs and little public discomfort, he said.

“We can actually conserve the same amount or more very easily,” Pritchard said. “Wouldn’t that be the more prudent approach?”

Other environmental concerns, including the fate of fish eggs and plankton sucked up by the plant’s intake pipes, have less support in the desalination industry. Carlsbad uses a screen designed to keep out adult fish and larger ocean life, but eggs can slip through and are destroyed inside the plant. The impact on the marine ecosystem from desalination plants is not well studied and is largely site-specific, according to the Pacific Institute, an environmental research group focusing on water issues.

Critics have called for finer meshes to keep out even eggs or for subsurface intakes, which place pipes underneath the sea floor and rely on sand to naturally filter out almost all organisms. State regulators in May called for subsurface intakes in all new desalination plants unless they are infeasible. The new rules will add up to $1 billion to the cost of some projects, according to Gasson, the trade magazine publisher.

$1 Billion Babies

“To say that’s it’s proportionate to spend $1 billion to protect these little fish eggs, which are almost certainly going to die anyway, it’s crazy,” Gasson said. “It’s saying we want to dry out in some desert and disappear.”

Pritchard countered that even if many fish wouldn’t survive until adulthood without the plant they are still being removed from the ecosystem and would have been eaten by other animals.

On a global scale, the Carlsbad plant will not be a major player. Another IDE desalination facility, Israel’s Sorek plant, produces 165 million gallons per day. Saudi Arabia’s Ras al-Khair plant has the capacity for 264 million gallons per day, though it uses other methods in addition to reverse osmosis.

The technology has already been proven viable around the world, said Snehal Desai, global business director for Dow Water & Process Solutions. Dow is one of the world’s largest reverse osmosis membrane manufacturers and supplies the Carlsbad plant. But the industry is still watching what happens in Carlsbad.

“For the U.S. market and California, all eyes are on the facility and hitting the numbers,” Desai said. “It’s going to be a bellwether for whether seawater desalination takes on a bigger profile in the U.S.”

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