Desalination has long been associated with one process — turning seawater into drinking water. But a host of new technologies are being developed that not only are improving traditional desalination but opening up new frontiers in reusing everything from agricultural water to industrial effluent.
A ferry plows along San Francisco Bay, trailing a tail of churned up salt, sand, and sludge and further fouling the already murky liquid that John Webley intends to turn into drinking water. But Webley, CEO of a Bay Area start-up working on a new, energy-skimping desalination system, isn’t perturbed.
“Look at the color of this intake,” he says, pointing to a tube feeding brown fluid into a device the size of a home furnace. There, through a process called forward osmosis, a novel solution the company developed pulls water molecules across a membrane, leaving salt and impurities behind it. When low temperature heat is applied, the bioengineered solution separates out like oil, allowing clean water to be siphoned off.
This method uses less than a quarter of the electricity needed for standard desalination, making it easier for the technology to run on renewable power, said Webley. His company, Trevi Systems, recently won an international low-energy desalination competition and is building a pilot solar plant to desalinate seawater in the United Arab Emirates.
With world water demands rising and extreme droughts like the one now gripping California expected to grow more frequent and widespread as the climate warms, drawing fresh water from oceans and other salty sources will be increasingly important.