Editor’s Note: This is the first in a three-part series on the development of seawater desalination plants in California and other drought-prone regions, looking at the environmental and economic challenges involved.
When the tiny coastal town of Sand City, Calif., fired up its desalination plant earlier this year, it became the first city in the state to tap the Pacific Ocean to provide drinking water for its residents through a full-scale desalination plant.
And it won’t likely be the last. About 20 proposed plants up and down the California coast are wending their way through lengthy approval and permitting processes, as municipalities and water districts look for ways to meet future water needs of a thirsty state.
California’s communities are hardly alone. Thousands of facilities around the world are using a range of technologies to remove salt from water, while hundreds of desalination plants in the U.S. treat brackish water. Still, obstacles to their widespread use remain.
In California, high price tags and potential environmental impacts have drawn criticism and delayed projects. But observers say that Sand City’s solution may pave the way for a boom in projects, making the Golden State a likely bellwether for the future of seawater desalination in the United States.
“Sand City is pretty monumental,” said Timothy Dyer, chief technology officer for San Leandro, Calif.-based Energy Recovery, Inc., which makes devices for use in reverse osmosis desalination plants, including Sand City’s and about 70 percent of such plants worldwide.
“It’s a good indication of what we can expect,” Dyer continued. “We think [desalination plants] will be more accepted once they get started in California.”
But getting started is no small task. California is an extreme case in water-related matters, due to inadequate water supplies, aging infrastructure, an expanding population and the complicated politics and economics involved there in moving water around the state.
Further, while desalination could offer a way to meet water needs and safeguard against shortages, some observers say it could also aggravate climate change.
In California, where climbing temperatures are expected to decrease snow pack and therefore water supplies, the 20 or so proposed desalination plants could meet about 6 percent of the state’s overall water needs.
But the electricity required to operate energy-hungry plants means an increase in carbon emissions. Some fear this may harm efforts to meet the state’s ambitious greenhouse gas reduction targets.
“Desalination is an energy-intensive process,” said Heather Cooley, a senior research associate at the Pacific Institute, an Oakland, Calif.-based research group that focuses on water issues, including desalination. One key to both minimizing the environmental impacts of desalination and making it economically feasible is reducing the amount of energy needed to fuel the process.
Energy makes up about 40 percent of desalination costs. For reverse osmosis plants, which drive seawater through a semi-permeable membrane that separates salt from water, much of that energy goes to pressurizing water to push it through the reverse osmosis membrane. Most of California’s proposed plants, including the Sand City facility, are of this type.
Currently, efficient reverse osmosis desalination plants use about 2.5 kilowatts of electricity to produce one cubic meter of water.
Lisa Henthorne, director of the International Desalination Association, a nonprofit group based in Topsfield, Mass., said that the industry is aiming to bring that number down to about 1.8 kilowatts through increased efficiencies in the desalination process.
But that could still be too high for California. Meeting the state’s water needs is already an energy-intensive undertaking. The water sector accounts for about 20 percent of the state’s electricity demand, according to California Energy Commission figures.
Lawsuits and Permitting Delays
In November, voters in Marin County, Calif., approved a $105 million desalination plant that would produce about 15 million gallons of fresh water daily. The facility’s energy intensity is one focus of a lawsuit filed against the project last year by environmental group North Coast Rivers Alliance and several other plaintiffs.
Under normal, non-drought conditions, the Marin plant would consume about 10 million kilowatt hours of electricity per year, according to the project’s environmental impact report. But in drought conditions, that could shoot up to almost 77 million kilowatt hours per year, in a county that uses an average of about 1.4 million annual kilowatt hours.
If other projects are any indication, the Marin plant may have a long way before getting final approval.
The massive Carlsbad Desalination Project near San Diego has spent more than a decade in the planning and permitting process. The $650 million facility, expected to be the state’s second plant after Sand City, would deliver about 50 millions of gallons of water per day to meet about 10 percent of San Diego County’s water needs. It could be operational by 2013.
The project developer, Stamford, Conn.-based Poseidon Resources, which is also working on another 50 million-gallon-per-day plant in Huntington Beach, Calif., included a greenhouse gas emissions reduction plan in its environmental review process. The proposal includes energy efficiency measures, onsite renewable generation and carbon offsetting.
A Last Resort
Still, for cities that have other options, desalination is seen as a last resort, even with global warming mitigation strategies, said Tom Luster, an environmental scientist with the California Coastal Commission.
Sand City built its $12 million plant, which will produce about 98 million gallons of water per year, in the face of state-imposed water restrictions designed to replenish the overtapped Carmel River. Without the plant, construction and development in the city would have stalled, crippling the economy of a town heavily reliant on tourist dollars, city officials said.
While desalination could be a part of the solution, there are still other options available in other parts of the state and the country, experts say, including water conservation and efficiency, recycling and rainwater harvesting.
“It’s a matter of what you do first,” Cooley of the Pacific Institute said. “It’s going to come down to local communities deciding what resources they value.”
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