California’s growing population and shrinking Colorado River water supply do not necessarily mean the state will be in a water crisis anytime soon. In addition to greater reliance on traditional water sources, such as mountain snowpacks and neighboring states, the state is clearing the way to build up to five desalination plants by 2007.
Desalination, the process of converting sea water to drinkable fresh water, has long been technologically feasible, but it has been economically prohibitive in all but the most water-stressed regions of the world.
Freshwater sources are relatively abundant in the Western Hemisphere, and local governments invariably subsidize the extraction of water from nearby lakes, rivers, and aquifers. The world’s largest and most prevalent desalination plants exist in Saudi Arabia and other parts of the Middle East, where potable water is scarce. But continuing advances in technology are making desalination more economically attractive to western nations, and some American coastal regions in particular.
Florida has led the way in taking advantage of modern desalination technology by approving in 2001 a desalination plant for the Tampa Bay region. Construction is near completion, and the plant is expected to be operating at full capacity in March.
The Tampa Bay plant will be the largest desalination plant in the Western Hemisphere. To create potable water, the plant will take in 44 million gallons of saltwater per day from Tampa Bay. The saltwater will be pumped under great pressure through special membranes that extract the salt and other minerals from the water. Of the 44 million gallons taken in each day, 25 million gallons will be converted to potable water, while the remaining 19 millions gallons will absorb the combined salt extract. This 19 million gallons of briny water will be diluted with 1.4 billion gallons of water discharged every day from the Tampa Electric Company’s Big Bend power plant. In the end, the salinity of the power plant discharge water will increase from 26 parts per thousand, which is consistent with the overall salinity of Tampa Bay, to 26.3 parts per thousand.
“Desalinated seawater is a drought-proof, alternative water supply that can be produced in an environmentally and economically sound manner,” states the Tampa Bay water authority.
The Tampa Bay proposal makes sense to local government because technology has advanced to the point that converting saltwater to freshwater is not substantially more expensive than extracting potable water from nearby rivers and the Florida aquifer. Moreover, local governments have become increasingly sensitive to the calls of local environmentalists to alleviate the effects of periodic droughts. For a few extra pennies on the dollar, government officials crafted a solution that would provide freshwater without harming the region’s lakes, ponds, rivers, and wells.
The Metropolitan Water District (MWD) of Southern California is watching the Tampa Bay results closely. Although the MWD has tentatively approved the five proposed desalination plants, snags at the Tampa Bay desalination plant or a sister facility currently being built near the Tampa Bay Big Bend facility could cause MWD to change its mind.
The California plants will cost between $70 million and $300 million each. “It is expensive, but it’s not something of the other world anymore,” said Adam Ortega, an MWD spokesperson. In return, the desalination plants could supply up to 7 percent of MWD water by 2007. “Even though it only represents a small portion of the water we use, it’s an additional supply,” said MWD Chairman Phillip Pace.
In addition to Florida and California, Texas is researching desalination sites, and New Mexico is considering desalination technology to extract salt from its brackish groundwater. Officials from Iceland, Singapore, and Cyprus have visited the Tampa Bay facility and are reporting on the results to their governments.
James M. Taylor is managing editor of Environment & Climate News.