Mexican city considers desalination plant; U.S. partnership a possibility.The water for Arizona’s future needs may lie off the coast of a popular Mexican real estate resort, in the Gulf of California.
State officials are studying the idea of importing filtered ocean water from an as yet unbuilt desalination plant in Puerto Penasco, 60 miles south of the U.S. border. The water – potentially billions of gallons a year – would help sustain urban supplies in Arizona and could someday bring relief to rural residents, who have long sought a water source to replace rapidly depleting aquifers.
A Scottsdale company already is looking at possible designs for the plant in Puerto Peñasco, where overworked groundwater wells are on the verge of running dry. Arizona water managers see an opening for the state to team up with the seaside resort on a larger plant to serve both countries.
Such a project would raise a host of political, economic and environmental issues, and it’s not clear who would pay the construction costs, which could top $250 billion.
But if backers can clear those hurdles, Arizona and neighboring states could tap a plentiful supply of water largely immune to the effects of drought and climate change.
“Desalinated ocean water is the future sustainable source,” said Herb Guenther, director of the Arizona Department of Water Resources. “It’s only logical that eventually we’ll migrate toward it. We don’t need interim supplies now. We need a permanent supply.”
Oceans, which hold 97 percent of the Earth’s water, were long considered a source of last resort, mostly because of the high cost of removing enough salt to produce drinking water.
Big desalination plants operate widely in arid Middle Eastern nations, where water is pricey and energy is cheap, but only recently has the ocean emerged as a viable resource in the United States. At least two dozen plants are now on drawing boards in California, a state beset with water woes.
“People explored and utilized the most cost-effective sources of water as long as they could,” said Randy Truby, past president and a current director of the International Desalination Association, an industry group. “In California, they had the state water project, the Colorado River, sewage-water reclaim, conservation . . . but once you exhaust all of those things, seawater desalting is about the only place you can go.”
That’s where Puerto Peñasco finds itself. The city’s groundwater resources have dwindled after years of steady use. The wells produce poor-quality water, and many are nearly exhausted. With growing interest from American developers, the city decided to turn to the most obvious alternative: the ocean.
“The water needs are severe,” said Walt Bouchard, whose Scottsdale-based environmental consulting company was hired to study desalination options for Puerto Peñasco. “There are concerns that water may not be available for future development.”
A need for water
The city, also known as Rocky Point, has long drawn Arizonans looking for a quick trip to the coast, but in recent years it also has attracted American investors eager to build hotels and time-share condominiums. About 81 projects sit in the planning stages, Bouchard said, and “they are going to need water.”
Bouchard’s company was asked by city officials to determine the feasibility of a seawater desalination plant, settle on a technology, produce a blueprint and prepare a bid package for a company that would design, build and operate the plant.
The study is based on a desalter that would produce 11.4 million gallons a day at the start and up to 45.6 million gallons a day by 2020, when the final stage is completed. That is enough water to serve at least 250,000 people a year.
Construction costs will depend on the technology, the location, the workforce and other factors. Poseidon Resources, a private company, is working on a plant near Huntington Beach, Calif., that could produce up to 50 million gallons of drinking water a day. The company estimates it will cost $250 million to build.
Mayor Heriberto Rentería put the Puerto Peñasco project on a fast track, with a goal of firing up the first desalination module by 2010 or 2011. Bouchard said his team expects to deliver its findings by the end of the year.
So far, the plan calls for a plant that would produce water for the local and tourist demand, but Bouchard said the city is aware of Arizona’s interest and could consider a joint project once Puerto Peñasco’s needs are met.
“Could they supply water to Arizona? The answer to that is very likely yes,” Bouchard said. “We believe it is feasible. The question becomes what about the cost of conveyance? Could it work for Arizona? As part of the state’s overall water portfolio, it might have a place.”
A Mexican partnership
Arizona isn’t desperate for water yet, but the prospect of finding a Mexican partner in Puerto Peñasco persuaded state officials to start planning now. In June, the Arizona-Mexico Commission, a non-profit trade and business group that works with government officials, endorsed a plan to study the feasibility of a jointly operated U.S.-Mexico desalination plant on the Gulf of California.
That study will look at a range of issues, including cost, funding sources, energy needs and environmental effects on the gulf. Its findings could point toward a joint project with Mexico or to some other alternative. The major players so far are Puerto Peñasco; the states of Arizona and Sonora; and Arizona’s two largest water providers: Central Arizona Project and Salt River Project.
“CAP does not need the water today or for a good long while, not for 20 years, maybe 30,” said Tom McCann, CAP’s resource planning manager. “But the opportunity presented itself, and if we don’t do it now, it could slip away for another 40 years. Just because we don’t need it, others could.”
McCann said neighboring California and Nevada, which are desperate for water, could participate in the project and use their share of water early, before Arizona needs it. Other Arizona cities also could help build infrastructure that could allow water exchanges as far away as Flagstaff or Prescott.
Although water from a plant would probably be used mostly in southwestern Arizona to start, it would give the entire state added security. Water normally drawn down the lower Colorado could remain in Lake Mead, offsetting the risk of shortages. Water made available to rural areas could help protect rivers and riparian habitat.
“Water is limited in Arizona, and it’s a lot easier to help people find supplies than to fight over supplies,” said John Hetrick, water-rights analyst for SRP. “One of our tactics has been to augment Arizona’s water supplies. If we can help solve a community’s problems, we can avoid a conflict in the future.”
The price of water
Potential roadblocks exist. One of the biggest unanswered questions for this project and any new desalination plant is how it will be powered. Desalting ocean water requires significant amounts of energy, which is why many of the early plants were built alongside power plants.
The proposed Puerto Peñasco plant would likely be built in stages. The first stage could operate using power from the existing electrical grid, but at full operation it would need additional sources. Bouchard, the consultant on the project, said his team is exploring clean technologies, such as a solar-energy array that uses molten salt, a technology that allows a power plant to store electricity after the sun sets.
A higher-capacity U.S.-Mexico plant would require even more electricity, which is another issue under study by the Arizona consultants.
The environmental effects of a desalination plant also raise red flags. Seaside plants can disturb or damage ocean habitat and risk contaminating the water with chemicals used in the process. The waste product – a concentrated brine – threatens sea life and water quality.
A National Research Council study released earlier this year warned that significant uncertainties remain about the environmental effects of seaside desalination. The council said researchers need to more thoroughly explore what happens on both ends of the process.
Protecting the ocean will make the water more expensive, but “part of the real cost of desalination means spending the money to properly address the environmental impacts,” said Peter Gleick, president of the Pacific Institute, a non-profit research center in Stanford, Calif., that monitors water and the environment.
“It’s a classic economic issue, making sure the full costs are addressed. We can’t ignore environmental costs.”
The institute studied California’s plans to expand desalination and concluded that cities in that state could find water more quickly and cheaply through conservation and better management of existing resources.
For an inland state like Arizona, desalinating mineral- laden groundwater might be cheaper and require less energy, Gleick said. Filtering seawater and moving it even a short distance could push prices so high that no one will buy it.
An acre-foot of desalinated seawater costs from $750 to more than $1,200, depending on the location and the technology used. CAP and SRP sell water to cities and agricultural customers for $30 to $110 per acre-foot, and farmers along the Colorado River rarely pay more than $50 an acre-foot. An acre-foot is 325,851 gallons, enough to serve one or two typical households for one year.
California’s higher water costs have made desalinated supplies more attractive. Municipal customers pay about $600 per acre-foot to the Metropolitan Water District of Southern California, the region’s largest water provider.
The break-even point could take longer to reach in Arizona, especially if rising energy prices push the cost of desalination higher. The gap could close faster if the same high energy prices raise the cost of traditional water sources, such as the CAP Canal, which moves supplies 336 mostly uphill miles.
“We are spoiled by cheap water,” said Guenther, the state water chief. “Right now we’re fighting over the few remaining scraps of an inexpensive water supply. We’ll have to get used to the fact that these alternative or sustainable supplies are going to be considerably more expensive than we’re used to. We’re going to have to bite the bullet.”
Posted by http://www.azcentral.com
