One of the biggest complaints about hydraulic fracturing ("fracking"), the process where pressurized fluids--including water and lots of chemicals--are injected into the ground to fracture shale rock and tap into natural gas reserves, is that it’s dirty. Something has to be done with all of the chemical-filled water that’s pumped into the ground, as well as all the "produced water" that comes up to the surface with natural gas. Or else it gets into our drinking water and can result in serious health concerns and explosions at the faucet.
One solution for dealing with the produced water: purify it really, really well. A new water distillation process developed by researchers from MIT and King Fahd University of Petroleum and Minerals in Saudi Arabia vaporizes water under the boiling point when it comes into contact with a carrier gas. The resulting moist air bubbles pass through even cooler water and the vapor condenses. In case you didn’t get that, it’s basically the standard distillation method (like how you make alcohol)--a humidification-dehumidification desalination system, where salty water is vaporized and condenses on a cool surface--but with a twist: the temperature difference between the warm and cool water is significantly less, and the process is both more efficient and cheaper.
Traditional distillation systems do become cheaper at scale, but that’s not helpful for rural areas that don’t need to desalinate large amounts of water. In contrast, MIT’s technology works best in a smaller size--producing 1,200 to 2,400 liters of water a day, or the amount of water needed for a rural village. And unlike other desalination systems, saltiness doesn’t affect MIT’s technology, making it ideal for producing water from fracking.
So far, MIT has built a 12-foot-high test unit for the technology in one of its labs. The unit produces approximately 700 liters of clean water daily (the original water comes from natural gas wells). The next step is scaling up, and beginning commercial operation as soon as two years from now.