Low-energy desalination in Vancouver

A better way to take salt out of seawater

Toronto Star: The world isn't facing a water shortage. Anyone who lives by the ocean knows that. What we are running short of is fresh water. Only 3 per cent of the water on this planet is considered fresh water, and of that about two thirds is locked up in glaciers. Most of the rest isn't close to people who need it most, with parts of Australia, India and the U.S. southwest being some of the better known water-scarce regions.

This has brought heightened attention recently to the importance of water desalination, and more specifically, lower-cost ways of removing salt from seawater that don't require enormous amounts of heat and electricity. On this front, a start-up from Vancouver called Saltworks Technologies has been breaking new round with a process called 'thermo-ionic desalination.'...

Most of the world's desalination plants today separate salt by distilling seawater, but this requires an immense amount of energy to rapidly vaporize and then condense the water. Newer desalination plants typically use a process called reverse osmosis. This is when the seawater is forced against a membrane that filters out the salt and other minerals. The approach is less energy-intensive than distillation, but the big pumps that push the water through the membrane still require lots of electricity...

This is why a company like Saltworks is so important... Ben Sparrow, the mechanical engineer who co-founded Saltworks in 2008, says a small pilot plant is already operating in Vancouver that can process 1 cubic metre of ocean water a day. [Read about the process here.] The beauty of this approach is that no external energy is required...

Saltworks needs to show the process can be scaled up to handle millions of cubic metres of water annually... Joshua Zoshi, co-founder and president of Saltworks, says a commercial plant that could handle 50,000 cubic metres a day would require an evaporation tower 80 metres in diameter. Building such a structure shouldn't pose a challenge. 'That's a well-known, well-practised engineering discipline,' he says.

Image source here.