Cheaper Desalination – Saltworks Breakthrough

November 16th, 2009 by Paul O’Callaghan

Paul O’Callaghan is CEO of Cleantech consultancy firm, O2 Environmental Inc. and author of Water Technology Markets.

Canadian firm, Saltworks Technologies, just came out of stealth in relation to their desalination technology, which they claim reduce the electrical energy required for desalination by over 70%. They report they can produce 1m3 of water with 1kW hour of electrical energy, compared to the 3.7kWhr per m3, which is what is currently achievable using reverse osmosis with the use of energy recovery devices.

[social_buttons]So how to they do it? Well its novel. It appears to be a new approach. And novel and new are two things scarce as hens teeth in relation to desalination technologies.

They use solar heat (or waste heat) to evaporate water and concentrate salt water. They are converting solar energy into osmotic energy by doing this. They then use this osmotic energy to desalinate water.

They then expose the concentrated salt water to two separate solutions of regular salt water via two different ‘bridges’, one which is porous to chloride ions, the second which is porous to sodium ions.

The sodium and chloride ions migrate across the respective bridges into the salt water solutions to equalize the difference in ion concentration between the solutions.

This creates two charged solutions, one enriched with sodium ions (positively charged), the second enriched with chloride ions (negatively charged).

These two solutions are then exposed across two similar bridges to the water to be desalinated. This draws sodium ions into the chloride enriched solution and draws chloride ions into the sodium enriched solution: Net result desalination. Doing this they reckon they can produce 1m3 of water using 1kWh of electrical energy, which is used to pump fluids around the pipework.

Because the system is not under pressure, they can use plastic pipes instead of steel pipes, potentially reducing capital costs also.

I met with Saltworks about six months ago in Vancouver and I was impressed by the methodical way they have been going about technology commercialization. Despite winning a technology innovation award in British Columbia in May 2009, they have kept this remarkably quiet.

An article in the Economist provides a good review of this.

Image credit: Snap a creative commons via Flickr











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