Indian Ocean: view from Reunion Island. Pixabay
Many arid or dense countries, such as Malta, Israel, and the United Arab Emirates, now rely on desalinization to provide water. And now, there is an additional way to get fresh water from the sea, due to the creation of floating desalination machines that use “no electricity” and are “100% mechanically driven”:
Oneka’s floating desalination machines – buoys anchored to the seabed – use a membrane system that is solely powered by the movement of the waves. The buoys absorb energy from passing waves, and covert it into mechanical pumping forces that draw in seawater and push around a quarter of it through the desalination system.
The fresh, drinking water is then pumped to land through pipelines, again only using the power provided by the waves.
This is a useful advance, notes the BBC, although it is not clear how large a volume of fresh water it can produce. Still, unlike
large, shore-based desalination plants typically require vast amounts of energy to remove the salt, Oneka’s small units are powered solely by the movement of the waves….More than 300 million people around the world now rely on desalinated water, according to the global trade body, the International Desalination Association. This water is supplied by more than 21,000 plants, almost twice as many as there were 10 years ago. Demand for such plants is likely to grow further, as the world population grows and climate change continues to put pressure on fresh water supplies.
There are currently two techniques used to desalinate seawater – thermal and membrane. In thermal-based desalination, seawater is heated until it evaporates, leaving the salt behind. It is typically very energy intensive.
The membrane-based system, also known as reverse osmosis, works by pushing saltwater through a semi-permeable membrane, which catches the salt. This still requires a significant amount of energy, but less so than thermal.
The floating desalination machines do not require any energy other than that generated by the waves.