How Desalination Could Help Power Cities

As freshwater supplies shrink, many cities are building more desalination plants to turn seawater into drinking water.

Why are coastal cities turning to osmotic power? What if cities could make electricity just by mixing river water with seawater?

Every year, about 15,000 TWh of energy flows into the oceans as freshwater meets saltwater at river mouths — almost half of the world’s yearly electricity use.

Now, a new technology called osmotic power may let us capture some of that energy. It can run day and night, producing clean, steady electricity.

These plants use a lot of energy, but they also produce extremely salty wastewater. Instead of dumping that brine back into the ocean, osmotic power systems could use it to generate electricity.

So how does it work? And could mixing fresh and salty water really become a simple way to help meet the world’s growing energy demand?