Next-Gen Desal Plants go from Rare to Routine

The world is on the verge of a water crisis. Rainfall shifts caused by climate change plus the escalating water demands of a growing world population threaten society’s ability to meet its mounting needs. By 2025, the United Nations predicts, 2.4 billion people will live in regions of intense water scarcity, which may force as many as 700 million people from their homes in search of water by 2030.

Those water woes have people thirstily eyeing the more than one sextillion liters of water in Earth’s oceans and some underground aquifers with high salt content. For drinking or irrigation, the salt must come out of all those liters. And while desalination has been implemented in some areas — such as Israel and drought-stricken California — for much of the world, salt-removal is a prohibitively expensive energy drain.

Recent innovations could bring costs down and make the technology more accessible. A new wonder material may make desalination plants more efficient. Solar-powered disks could also serve up freshwater with no need for electricity. Once freshwater is on tap, coastal floating farms could supply food to Earth’s most parched places, one scientist proposes.

In 2015, more than 18,000 desalination plants worldwide had the annual capacity to produce 31.6 trillion liters of freshwater across 150 countries. While still less than 1 percent of worldwide freshwater usage, desalination production is two-thirds higher than it was in 2008. Driving the boom is a decades-long drop in energy requirements thanks to innovations such as energy-efficient water pumps, improved membranes and plant configurations that use outbound water to help pressurize incoming water.

Seawater desalination in the 1970s consumed as much as 20 kilowatt-hours of energy per cubic meter of produced fresh-water; modern plants typically require just over three kilowatt-hours.