Steps 1 through 3
After approving and getting permits and buying land and making deals over the past six years, the $1 billion
Carlsbad, California desalination facility's construction is close to completion. The hope is that Carlsbad will be producing up to 50 million gallons of desalinated water a day. It is a big experiment in a state that is suffering one of the worst droughts on record
that may not get better before it gets much much worse. That being said, the planet Earth is pock-marked with
idle desalination plants.
Still, some scientists and environmental groups contend that if rainy conditions return to California, the plant here and others like it could become white elephants. Santa Barbara, northwest of Los Angeles, built its desalination plant a quarter-century ago and promptly shut it down when rains returned.
Australia is a more spectacular case: It built six huge desalination plants during a dry spell and has largely idled four of them though water customers remain saddled with several billion dollars’ worth of construction bills.
However, environmentalists feel that desalination should be a last resort solution and ends up being a case of
robbing Peter to pay Paul.
The downside, however, is that seawater desalination is not very energy efficient. To turn saltwater into freshwater, it's pushed through a very thin polyamide membrane. While the water molecules pass through with no trouble, salt molecules do not.
The trouble with the process, known as reverse osmosis, is that it consumes between three and four kilowatt hours per cubic meter - 1,000 liters - of fresh water. That equates to three times the amount of CO2 emissions generated in the treatment of river or ground water.
The treatment plants will produce tons of the CO2 emissions that we are all hoping to curb and the added salt to the ocean may reek havoc on the marine ecosystems surrounding the coastlines. Proponents of desalination say the technology has gotten better and point to the growing numbers of desalination plants around the world—more than 17,000 according to the
International Desalination Association.
Besides the drought and growing populations needing more water resources, the money is why desalination is gaining more support.
The rising interest in desalination is not simply a matter of desperation, though that is certainly a factor in states with growing populations and few obvious sources of new water. Advocates say the technology has improved markedly over the past 20 years. While the water can cost twice as much as conventionally treated water, it is still less than a penny a gallon, and that is starting to look tolerable in parched regions.
San Diego is an interesting example in desalination since they have been one of the more water conservative places in the U.S.
Mr. Weston, the chairman of the San Diego County Water Authority, said his agency and others in the area had gone a long way toward embracing conservation. Since 1990, water use in the county has been cut 12 percent, even as the population has jumped 30 percent.
Long worried about water scarcity, the San Diego region helped to pioneer measures that ultimately spread across the country, including low-flow bathroom fixtures, more efficient washing machines and other innovations.
I can tell you that, being a California resident, there is a palpable anxiety about water now that wasn't here even a year ago. It will be interesting to see how municipalities react now that the citizenry might start asking questions and want answers.