On May 14, 2009, the San Diego Regional Water Quality Control Board announced that it had approved a $320-million desalination plant with capacity to provide 50 million gallons (200 million liters) of clean water per day when completed in 2012 . In a state known for its sometimes acrimonious opposition to desalination plants (on environmental grounds) the decision to build the San Diego plant was unanimous. As of mid-2009 there were 20 more desalination plants waiting approval in California. Clean Water has clearly become a huge issue in the Golden State.
Clean Water, Dirty Power
Water desalination is energy intensive. Desalination plants follow the traditional energy pattern: most of the energy comes from burning fossil fuels and thereby emitting CO2 and dumping other forms of pollution into the environment – including water streams.
While the desalination plant press releases don’t mention the energy component, every desalination-plant investment has to be coupled with parallel investments in power plants. According to the World Bank, “the typical ratio of power to water was 50MW: 22,500 m3/day water.” The San Diego desal plant will produce 200,000 m3. Following that ratio, the San Diego desalination plan would need the equivalent of a brand new 444-MW power plant to provide the energy for cleaning the saltwater.
Burning coal to clean water seems dysfunctional, to put it mildly. According to the Union of Concerned Scientists, the “typical” 500-MW coal plant generates 193,000 tons of sludge, 125,000 tons of ash, and 10,500 tons of nitrous oxide (NO2)—the equivalent of half a million old cars on the road. . All of that garbage goes on or in the ground somewhere. If it is buried it may end up seeping into the groundwater, which gets polluted with toxic waste, including mercury and arsenic. That of course would decrease the supply of clean water and spur the development of more desalination plants. Dysfunctional indeed.
Clean water needs clean energy. Burning fossil fuels to clean seawater or brackish water is unsustainable and unaffordable in the long term.
Entrepreneurs who find ways to lower the energy use to desalinate water and those who find ways to clean water with clean energy have a huge opportunity ahead of them.
Sources:
“Desalination Plant is Approved,” The New York Times, May 14, 2009, http://www.nytimes.com/2009/05/14/science/earth/14aquifer.html?_r=1&scp=3&sq=desalination&st=cse
World Bank, “Seawater and Brackish Water Desalination in the Middle East North Africa and Central Asia,” Final Report, December 2004
Union of Concerned Scientists, http://www.ucsusa.org/clean_energy/coalvswind/c02d.html
