Low Cost Desalination – Saltworks Breakthrough

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.
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 equalise 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 commercialisation. 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.

Paul O’Callaghan is CEO of Technology Assessment Group, O2 Environmental Inc and author of Water Technology Markets.

4 replies
  1. Vanguard Funds
    Vanguard Funds says:

    Efforts were on throughout the world for low cost desalination and by achieving this Saltworks technologies have created history. This will definitely help mankind in long term.

  2. Anonymous
    Anonymous says:

    When I read of such WORLD BEATING concepts I like to recite my favourite saying. Yes you'll be punished:Optimism is born out of Blissful Ignorance.Pessimism is the product of BITTER experience.I am curently working on an Australian Desalination (Reverse Osmosis) Plant Project and have just completed another. A concept such as this one sounds good but the energy component of COST, although important is only one aspect. We need to know the operating costs, and capital costs, as if the cost of money outweighs the energy savings, it's DEAD in the WATER. In addition, plants with large foot prints will be difficult to sell to the public.I'm interested to hear from the proponents as to the total costs. A 1000L/day pilot plant is really TINY compared with 125,000,000L/day and more plants up to 600ML/day.What is the real cost?

  3. Lawrence Curtin
    Lawrence Curtin says:

    We have developed a device that is scaleable that desalinates sea water and/or removes the waste from waste water. We have built a small model.This uses only photovoltaics. We are at http://www.photovoltaics.com It can be grid connected.We have also made different materials that draws the potassium/sodium ions to one polarity and the cholrine/sulfate ions to the other. You attach these to a load and you get .90 volts with the current dependant upon the material size.All of the above as stated is scaleable.The materials are not expensive. Patents have been filed.

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