Cheaper desalination comments

Current thinking
A fresh way to take the salt out of seawater
See articleOct 29th 2009 |

Readers' comments
The Economist welcomes your views. Please stay on topic and be respectful of other readers. Review our comments policy.

Kroneborge wrote: Oct 29th 2009 9:06 GMT wow, this sounds like it could be very cool. If it works at scale, you could combine this with solar panels and transorm the desert in a very environmentall sound manner.

joannetsu wrote: Oct 29th 2009 9:10 GMT Ironic that this comes from Vancouver, the land of endless rain and no sun. :P

DSS wrote: Oct 30th 2009 3:15 GMT Years ago I visited a small Israeli power station which used the difference in salt concentrations between the Jordan river and the Dead Sea to generate electricity by the use of just such ion bridges. In retrospect, why didn't those clever Israelis think of doing things the other way around to create drinking quality water from that brackish lower Jordan river? They could certainly do with the extra fresh water there.

Like all great inventions, this is the sort of thing where people around the world go "D'oh! Why didn't I think of that?".

Heshler wrote: Oct 30th 2009 3:40 GMT What a beautiful idea. My question, however, is will this water be sanitary? DI and RO remove many contaminants on top of NaCl... will this process do the same? Would it be necessary?

Rajesh Haldipur wrote: Oct 30th 2009 4:24 GMT Sounds too good to be true. But if it is true, it can change the world as we know it. Deserts can bloom. The world can have as much drinking water as it needs, where it is needed.
The only other BIG problem we have to tackle is carbon emissions. Which can also probably work out with cheap solar energy, as Kroneborge points out.

Pierofor wrote: Oct 30th 2009 11:50 GMT Please correct you diagram ,it is wrong see the correct one at http://www.saltworkstech.com/technology.php.
Recommended (7)PermalinkReport abuse

FiniteResources wrote: Oct 30th 2009 1:42 GMT Does the low pressure and initial evaporation stage make for a large physical footprint in order to obtain worthwhile amounts of fresh water? Other than that, it sounds like a brilliant idea that will hopefully inspire others to design low genuinely low energy equipment and processes.

KCCM wrote: Oct 30th 2009 1:59 GMT Very cool - the engineer in me remains positive that humanity can address its challenges through just such innovative and efficient ideas.
Recommend (4)PermalinkReport abuse

Scarecrow wrote: Oct 30th 2009 3:02 GMT Interesting idea, but an investment in this technology might have a very low internal rate of return. The output of the pilot plant mentioned on their website (1 cubic meter per day) barely attains the fresh water consumption of a single family. And a salt water source has to be nearby, which is not always the case in arid areas.
Recommend (4)PermalinkReport abuse

Florence Fok wrote: Oct 30th 2009 4:29 GMT It combines the use of solar and the preservation of water. Cool!
RecommendPermalinkReport abuse

bahadur wrote: Oct 30th 2009 4:47 GMT This too requires Electricity, many be less. During my younger days when I used to be posted in backward areas, we had developed a solar evaporator cum condenser distillation plant which worked perfectly in our Indian climate giving three litres of distilled water per square meter per day. I have used it extensively for Automobiule batteries, for cooking hard lentils and also (rarely) for saline Injections; all with perfect safety. The latent heat used up for evaporation is given back during condensation and the energy consumed is quite small. Warning: It does not work on cloudy days which means four months in Eastern India.
Recommend (8)PermalinkReport abuse

generated3421714 wrote: Oct 30th 2009 4:57 GMT Sounds good, but I predict the problem will be in keeping the electrodes working. They will get fouled, and the resistance will increase. The cost of keeping the electrodes functioning well needs to be included in any evaluation of the net benefit.
Also, why not include a plastic covering over the pool? The evaporating water will condense on the plastic--- and that water is pure.
Recommend (12)PermalinkReport abuse

GEOPOLITICONOMIST wrote: Oct 30th 2009 7:06 GMT That’s all very well, however there’s a much more efficacious technology for massive water recovery that is being engineered with naturally applied simplicity. My invention is the high-temperature generating atmospheric domes that desalinate seawater drawn from the inflow of rivers to produce volumes of freshwater for domestic, irrigation and industrial needs by an artificially engineered hydrological system. Constant inflow of seawater is regulated according to the time of year and time of day relative to the movement of the tide so that the supply along the rivers to the domes will not be interrupted. Thermal build up of higher than normal temperature, within the geodesic structures, created by incoming infrared and excess ultraviolet radiation transformed via concentrated solar power into solar thermal energy and then with the additional heat generated by high light-transmitting low emissivity glass cause the cooling mechanism of evaporation to become a volume phenomena. Surplus freshwater is piped or channelled into domed reservoirs where it will undergo a distillation process to naturally replenish purified drinking water. Proposal will be made to construct and develop the first fully operational hydrological rivers system for the purpose of recovering water safely and massively (avoiding all potential sources of water contamination) to meet human and *reforestation needs.

*With the creation of top soil (from deciduous forest in autumn) availability for reforestation the region will naturally be able to effect climate change in a positive way.
Recommend (6)PermalinkReport abuse

swh wrote: Oct 30th 2009 9:23 GMT Please, consult either a thermodynamics textbook or someone that actually knows about desalination like Saltworks. On their website the claim is that "The energy reduction is achieved by harnessing low temperature heat and atmospheric dryness to overcome the desalination energy barrier" It is the low temperature heat (waste heat from power plants) that may work rather than solar evaporation. For the latter it would be much simpler to evaporate and condense water like bahadur suggested.
Recommend (2)PermalinkReport abuse
Johan Sterk wrote: Oct 30th 2009 9:26 GMT @Rajesh Haldipur:

"The only other BIG problem we have to tackle is carbon emissions. Which can also probably work out with cheap solar energy, as Kroneborge points out".

The fresh water can be used to grow trees in arid places. Trees consume CO2.
Recommend (1)PermalinkReport abuse
Johan Sterk wrote: Oct 30th 2009 9:28 GMT @Rajesh Haldipur:

"The only other BIG problem we have to tackle is carbon emissions. Which can also probably work out with cheap solar energy, as Kroneborge points out".

The fresh water can be used to grow trees in arid places. Trees consume CO2.
RecommendPermalinkReport abuse

NeilJT wrote: Oct 31st 2009 1:59 GMT Stunning discovery/development/innovation. Nobel prize for Green Technology - if it doesn't exist - about time it did...
Recommend (1)PermalinkReport abuse

rchrenko wrote: Oct 31st 2009 2:04 GMT @Johan Sterk: "The fresh water can be used to grow trees in arid places."

Desalination presupposes the presence of salt water to produce fresh water. Most arid areas (apart from coastal zones or inland salt seas) lack even salt water. In addition, any desalinated water from inland salt seas used for tree-growing would evaporate into the atmosphere, thus depleting existing supplies and rendering the concept unsustainable.
RecommendPermalinkReport abuse

generated3423281 wrote: Oct 31st 2009 9:36 GMT This is a terrible idea. Anything that enables population explosion is bad for us ALL. Overpopulation is the cause of nearly every problem, directly or indirectly.

And if we can just make fresh water, why worry about polluting ground water and surface water?

Bad idea. Just because we CAN do something doesn't mean we SHOULD.
Recommend (2)PermalinkReport abuse
JustNeil wrote: Oct 31st 2009 11:19 GMT Well its not an apples-to-apples comparison is it?
They're still using as much if not more energy as the other processes but just that a lot of it is coming as solar power and they're counting that as free.
It would be easy to modify the other methods to use solar power too... For example you could use a Solar Still as an evaporation chamber and then you would get fresh water for free, as it would use no electricity at all. The water would be purer than their method too.