Today, major cities around the world use reverse osmosis or multi-stage evaporation to provide fresh water to hundreds of millions of people.
First, desalination still requires a lot of energy — three to four kilowatt-hours of electricity to make 1,000 liters of freshwater using reverse osmosis.
The energy needed for desalination has been falling for decades as engineers have drastically improved the systems.
In fact, renewable energy can easily power reverse osmosis.
When communities face droughts and growing populations, could seawater treatments prove to be sustainable methods to deliver an essential water supply to those who need it?
Does the desalination brine make the ocean saltier?
The fresh water produced also eventually returns to the sea, so that the amounts of water and salt in the ocean are, overall, unchanged.
Desalination plants are also drought resistant.
Major coastal cities are continuing to grow rapidly.
Current and future desalination technologies can safely and sustainably make the oceans part of the solution to the world’s rising need for fresh water.