David Kirkpatrick

September 7, 2010

Low cost desalination for potable water

Via KurzweilAI.net — A theoretical device from the recently concluded Singularity University. This sounds like a fresh water solution with real promise.

From the first link:

Our approach leverages advances in 3 exponentially growing fields: synthetic biology, nanotechnology, and solar energy.  Synthetic biology is a factor because synthetic molecules are currently being developed that can create ionic bonds with sodium and chloride molecules, enabling fresh water to pass through a nanofilter using only the pressure of the water above the pipe.

Nanotechnology is relevant for reverse osmosis, because using thinner filter further reduces the amount of pressure required to separate fresh water from salt water. A filtration cube measuring 165mm (6.5 inches) per side could produce 100,000 gallons of purified water per day at 1 psi. Finally, as advances in solar energy improve the efficiency of  photovoltaics, the throughput of solar pumps will increase significantly, enabling more efficient movement and storage of fresh water.

Although the individual components described above have not advanced to a point where the solution is possible at present, we were able to speak with leading experts in each of these areas as to the timeline for these capabilities to be realized.

Synthetic molecules capable of bonding with sodium and chloride molecules have already been created, but have not yet been converted to an appropriate form for storage, such as a cartridge. This is expected to occur in the next 2-3 years. Filters are currently in the 10-15nm range, and are expected to reach 1nm over the next 3-5 years. As with the synthetic molecules, 1nm tubes have been built; just not assembled into a filter at this point. Photovoltaics are currently approximately 12% efficient, but it is anticipated that 20% efficiency is achievable in the next 5 years.

A possible implementation of our Naishio solution. The pressure from the water volume is sufficient to propel fresh water across the membrane (A), and photovoltaics (D) generate all the energy needed to pump water from the repository (C) to the water tank and circulator (E). Sensors (B) communicate between the solar pump and membrane to regulate the water level and ensure it doesn’t become contaminated. (Image: Sarah Jane Pell).