In case you haven’t heard, California is screwed. The drought has turned our perennially water-challenged state into a desiccated husk. In these dire times, we look toward desalination, an idea long-promised but never quite delivered in the U.S. But a spate of new technologies—graphene, solar mirrors, and more—could finally make desalination viable for our freshwater needs.
The state of desalination is wonderfully summed up in a new article by Cheryl Katz in Yale Environment 360. There are at least 16 water desalination plants in some stage of planning along the west coast, including a billion-dollar megaplant near San Diego set to open in 2016. The San Diego plant will use the classic strategy of reverse osmosis—essentially pushing seawater through a semipermeable filter—but new upstarts are trying out radically new technologies.
For example, there’s the buzz material on everyone’s lips: graphene.
One of the hottest new technologies on the bench in laboratories in the U.K., Saudi Arabia, and South Korea and elsewhere is one-atom thick, perforated graphene membranes that can cut reverse osmosis desalination to a fraction of its current cost. Developed at the Massachusetts Institute of Technology, the membrane’s pores can be tuned to optimize permeability. The hang-up for now is how to mass-produce the material.
Or solar power, a process that produces salt as byproduct instead of brackish water, which no one knows what to do with in existing desalination plants.
[Water FX‘s co-founder Aaron Mandell] hopes to quell those concerns with his company’s new process utilizing large parabolic mirrors to collect and concentrate the sun’s energy. Inside this solar still, pure water evaporates, while solids remain behind…Mandell points out that his salt byproduct is dry and can be mined for useful chemicals, rather than winding up with hazardous brine that’s costly to discard.
There’s a whole of other ideas hatching out of labs: “porous carbon aerogel electrodes” that remove salt electrically, nanotechnology that prevents bacteria biofilms from clogging up filtration membranes, a “plant in a box.” Check out Katz’s full piece for all the details, and toast a future glass of seawater. [Yale Environment 360]
Top image: An artist rendering of the desalination plant near San Diego. San Diego County Water Authority
