How does desalination function?

Only a small fraction of Earth's water is fresh, and after excluding massive reserves like glaciers and ice caps, there’s barely any left. Since humans and much of the world's plants and animals can't live on salty water, people have always turned to the sea for the fresh water they need, whether for drinking, sanitation, farming, or, more recently, industrial uses.

In the past, desalination was viewed as prohibitively costly due to its high energy demands. However, since the 1950s, emerging technologies like reverse osmosis and multistage flash distillation have gradually shifted this perspective, especially in regions where freshwater is scarce but populations are large. For a deeper dive into the specific methods used, visit How Desalination Works. Now, let’s focus on how desalination is applied in real-life scenarios.

Take Australia as an example. The Water Services Association of Australia views their dry continent as a glimpse into the future of water systems in an increasingly hot and dry world. During a prolonged drought, Australia’s five largest cities began preparing for potential water shortages by constructing massive desalination plants, totaling $13.2 billion [source: New York Times]. While some criticize the plants, citing higher water bills, environmental concerns, and economic inefficiency, regional water authorities believe these plants will help address drought and water supply challenges for years to come.

Israel serves as another example of desalination in action. In the Middle East, where many nations face looming water shortages, Israel is relying heavily on desalination plants. The third of five major plants planned along Israel's coast began operation in January 2010, and for the time being, it is the largest reverse osmosis desalination plant in the world. Once all facilities are up and running, they’re projected to supply about two-thirds of the nation’s drinking water [source: Associated Press].

Desalination technologies are also being innovated on a smaller scale. Portable desalination kits are a prime example. Researchers at MIT are working to advance desalination to the nano level, utilizing electrostatic ion-selective membranes to avoid common issues associated with reverse osmosis, such as high pressure needs and clogging. The process, called ion concentration polarization, could prove valuable in disaster-stricken areas. While the units won’t produce the massive quantities of freshwater generated by large plants, they would be portable, self-sustained by solar cells or batteries, and could provide drinking water until infrastructure is restored [source: MIT News].

The future of desalination appears promising, with various research institutions tirelessly working to enhance both its efficiency and affordability. Before long, we may be sipping cool, refreshing water that, if left untreated, could have been harmful to consume.