Desalination has been regarded for decades as a solution for providing fresh water to places where it is scarce. With drought becoming more common around the world – sometimes even in places where water supplies were thought to be ample – there is increasing pressure to bring new desalination plants online.
San Diego gets only 12 inches of rain a year and has no groundwater. It gets half its water from the distant Colorado River, and that source is becoming increasingly unreliable. Thus, it is no surprise that America’s largest desalination plant is in Carlsbad, about 30 miles north of San Diego. That plant provides about 10% of the fresh water needs of the region’s 3.1 million people.
There are 11 desalination plants in California, and 10 more are proposed. Desalination is huge in Saudi Arabia, Australia and Israel. Globally, more than 300 million people get their water from desalination.
But there are problems. Desalination is expensive and energy-intensive. If the process is powered by fossil fuels, it contributes to global warming. There are ecological impacts as well since it takes two gallons of sea water to make a gallon of fresh water, and the gallon left behind is extremely briny and potentially harmful to dump back into the sea. The intake systems of desalination plants are also harmful to fish and other aquatic creatures.
The cost of desalination has dropped by more than half over the last 30 years but water from it still costs about twice as much as that from other main sources. The technology is getting better and cheaper, but the industry must confront and solve serious environmental and economic problems in order for desalination to be able to meet the needs of an increasingly thirsty world.
Photo, posted January 12, 2011, courtesy of Flickr.