When Cape Town came dangerously close to becoming the world’s first major city to run out of water, it was a wake-up call to all water-pressed cities around the world, such as Mexico City, Say Paulo, and Cairo. As the world’s population grows and climate change pushes temperatures up, water is set to become even scarcer. And while desalination has long been touted as a way to source near limitless amounts of water, the process of desalination is expensive and energy-intensive.
But things are changing in the world of desalination. For one, researchers are finding that graphene—a material that is just one atom thick—can filter water extremely efficiently. That’s because it acts as a sort of molecular strainer, with holes large enough for water but not salt molecules to pass through. Still, more work must be done to make graphene usable on a large-scale.
Another promising new solution for desalination is called temperature swing solvent extraction (TSSE). Basically, this method works as follows: a solvent whose water solubility varies with temperature is added to saltwater, and at room temperature, the solvent draws in water molecules (but not salt). The solvent (and its newly-absorbed water) is then drawn off and heated. The heat causes the solvent to separate from the water, which can then be collected, salt-free.
As for smaller-scale desalination projects, researchers are also finding that solar energy can be used to purify water efficiently. We must keep in mind that desalination isn’t a silver bullet for solving the world’s water issues. There’s still the problem of what to do with the salt brine that’s left over from the process, and of course, desalination requires lots of energy. Despite this, it seems we’re getting close to feasible desalination technology at a time where the world needs it most.
