Access to fresh water is going to become a big problem for a lot of people. The U.N. says by 2025, at least 1 in 5 people will deal with water scarcity. By 2050, the demand for fresh water will have increased by 50 percent.
There is one solution: filter the world's oceans. We have the technology to turn salt water into fresh water. It could eliminate worldwide water shortages overnight — so why don't we?
In a word: energy. Compared with filtering fresh water, desalination is still inefficient and expensive. Modern desalination plants use more than 10 times as much energy as plain old freshwater purification. That makes them much pricier for the same amount of water.
As the water crunch gets worse, desalination will get more use out of necessity — but the technology will get better, too. Researchers are building graphene filters that require less energy or using tiny, efficient electrical fields to push the salt ions out of seawater.
And in Israel, where drought has been dragging on for almost a millennium, they use rocks — specifically, porous lava rocks — to keep their plants' filters clean and cut down on expensive maintenance. Desalination already provides more than half of the country's water, sometimes for less than an average household in the U.S. pays today.