‘My tears are salt water.’ –Tom Waits


The process is called reverse osmosis (RO), and it’s the mainstay of large-scale desalination facilities around the world. As water is forced through the membrane, the polymer allows the water molecules to pass while blocking the salts and other inorganic impurities. Global desalination output has tripled since 2000: 16,000 plants are up and running around the world, and the pace of construction is expected to increase while the technology continues to improve. […]

Seawater desalination, in fact, is one of the most expensive sources of fresh water. The water sells—depending on site conditions—for between $1,000 and $2,500 per acre-foot (the amount used by two five-person U.S. households per year). Carlsbad’s product will sell for around $2,000, which is 80 percent more than the county pays for treated water from outside the area. […]

Already, some 700 million people worldwide suffer from water scarcity, but that number is expected to swell to 1.8 billion in just 10 years. Some countries, like Israel, already rely heavily on desalination; more will follow suit. In many places, “we are already at the limit of renewable water resources, and yet we continue to grow,” says John Lienhard, a mechanical engineer and director of the Center for Clean Water and Clean Energy at MIT. “On top of that we have global warming, with hotter and drier conditions in many areas, which will potentially further reduce the amount of renewable water available.”

{ Technology Review | Continue reading }

art { Evander Batson }