Thermal desalination consumes too much energy for large-scale deployment (about 80 megawatt hours per megaliter) and the brine by-product fouls aquifers and is devastating to aquatic populations. Reverse osmosis, on the other hand, uses comparatively less energy, but toxins such as boron and arsenic can still sneak through, and membranes clog frequently, reducing the lifetime of the filter. But the Los Angeles–based company NanoH2O won a spot on the 2010 Cleantech 100 list for a novel filter that uses 20 percent less energy while producing 70 percent more water.
