Evaporation Prevention Using Molecular Blankets

Makarand writes "According to this article in the New Scientist, a Canadian company is testing a technology to reduce water evaporation from reservoirs by spreading an ultra-thin blanket of organic molecules on the surface to block the escape of water molecules into the air. Trials conducted in India and Morocco showed between 30 and 45 per cent reduction in evaporation using this method. However, the long term ecological effects of reducing evaporation in lakes or reservoirs is not yet clear as evaporation prevention can increase water temperatures and affect the exchange rates of gases such as oxygen, nitrogen and carbon dioxide."

Comments

Re:Nice idea

[helix400]

Heh, next time I'll read the article before commenting.

Boating would be ok. Since this "blanket" isn't one physical object, but a collection of molecules...boaters could rip a path through the water, and these molecules would close off the exposed water. Wow, looks like the only hangup now is possible ecological issuegs.

Re:Swimming pools too

[Anonymous Coward]

these sort of products have been available for swimming pools for a fair while now afaik

eg

http://www.adirect-energy-source.com/pool/poolco ve r/liquid-blanket/liquid-blanket.htm

and http://www.flexiblesolutions.com/products/heatsavr /

Old hat

[njh]

We studied this in school. They use large alcohols as the skin (as covered in this article). The point is that it's usually distribution rather than storage that is the problem. (In Melbourne.au the annual evaporation rate is 3m - on a shallow 30m deep dam this means that it would take 10 years to evaporate the water away, assuming none is added. I have some old papers here from the 60s by the then Melbourne Metropolitan Board of Works about this idea.

If you are having problems keeping water due to evaporation then you need to choose a better dam site.

More interesting is a proposal to store stormwater underground. Firstly, the land area and evaporation issues disappear (to be replaced by similar issues :) but more importantly, the water is actually cleaned by the action of anerobic bacteria on the water.

Re:Old hat

[njh]

Actually, for drinking water you want it to be deep anyway because the UV gets down a long way and sterilises the water. The problem is that a reasonable reservoir might be 1km^3, which is about as big as the argyle diamond mine. It's taken 20 years to dig that out, and there has been diamonds to make it worthwhile. Another problem is supporting the sides - if you want it to be steep sided you either need reinforce with concrete, which is expensive, or find somewhere with good solid rock, which is hard to then dig.

Website URL and Possible Additional Application

[pipingguy]

Flexible Solutions

This might also be useful for refineries/chemical plants, etc. that maintain large atmospheric pressure reservoirs of dihydrogen monoxide for fire-fighting purposes.

Re:this is a BAD idea

[Anonymous Coward]

Generally, rain clouds develop from humid air, not because they happen to be over lakes. So reducing the evaporation from reservoirs or lakes by 45% won't necessarily change weather patterns.

Where do you think humidity comes from?

Re:Swimming pools too

[Jodaxia]

Actually creating monolayers of organic molecules reduces the surface tension of water.

Water with its strong tendency to hydrogen bond has a greater surface tension than that of an eight carbon simple alcohol. These alcohols form monolayers by hydrogen bonding with the water molecules. The hydrophobicity of their carbon chained tails creates an excess surface concentration, which at a great enough concentration forms a monolayer.

Background information: Patents

[XenonChloride]

The interested reader might want to have a look at the US patents of Robert Neville O'Brien, the founder of Flexible Solutions:

• PAT. NO. 6,303,133
• PAT. NO. 6,558,705

they're called Langmuir monolayers

[whovian]

As I recall correctly, this is not a new idea, but perhaps its implementation is. I had a professor who described this concept in the classroom over 10 years ago.

People wanting more info should STF(ree)W for Irving Langmuir or Langmuir-Blodgett monolayers, e.g.,

http://www.woodrow.org/teachers/chemistry/ institutes/1992/Langmuir.html

The crowning achievement of any chemist's career must be the honor of winning a Nobel Prize. This accomplishment was realized by Irving Langmuir in 1932. Langmuir was fascinated with surface chemistry and it was for his efforts in this area that he became the first non-academic chemist to receive the Nobel Prize. Along with Dr. Katherine B. Blodgett, he studied thin films and how substances are adsorbed on surfaces. Through their efforts, surface chemistry became a full-fledged scientific discipline. In addition to their interest in these surfaces, they also wanted to know more about interfaces, where phases come together. The studies led to clarification of the true nature of surface adsorption and established the existence of monolayers. Monolayers are surface films a single atom or molecule thick which have peculiar, two-dimensional qualities. Thin layers on surfaces such as living membranes are important in the action of enzymes, toxins, antitoxins and other biological substances. Again turning to the practical, this discovery led to the possibility of measuring molecular sizes of viruses and toxins, a significant step forward in the eyes of biologists. Langmuir developed experimental techniques for the study of proteins. The studies on monolayers also led to the development of almost perfectly transparent glass, made by placing a thin film of a flourine compound on the surface.

Re:This should be fun

[gpig]

Just wait until they make a version that replicates.. so you can pour 1 cup in a lake and in a few days it covers the lake....

Then wait until someone pours a cup of this into the oceans.

Then wait when it stops raining and we all die.

J.G. Ballard wrote a (fictional) book about this.

It is called 'The Drought'.

It is not a happy book.