Desalination 'not the solution'/WWF

[RestoreGore]

Desalination Not The Solution

Desalination 'not the solution'

Untapped resource: oceans contain 97% of the planet's water

Turning salt water into drinking water is not a solution to tackle global water scarcity, the WWF has said.

A report by the environmental group said a growth in the energy intensive technology would increase emissions and damage coastal and river habitats.

More attention should instead be paid to conserving supplies, it suggested.

The study was published as Australia announced plans to build one of the world's biggest desalination plants to supply drinking water to Melbourne.

"Desalinating the sea is an expensive, energy intensive and greenhouse gas emitting way to get water," said Jamie Pittock, director of WWF's global freshwater programme.

"It may have a place in the world's future freshwater supplies but regions still have cheaper, better and complementary ways to supply water that are less risky to the environment."

The report called for greater emphasis on managing existing supplies before the go-ahead was given to major water projects.

It added that new desalination plants, which were primarily located in coastal areas, should also be subject to tighter impact assessments to minimise damage to the marine environment.

Advances in technology meant that it was also possible to develop alternative "manufactured water" systems, such as treating waste water, the authors wrote.

end of excerpt.

As I have written here before, I too believe that desalination (reverse osmosis process) is an expensive GHG emitting procedure that is simply a bandaid on a crisis that will not be solved by looking to methods that actually exacerbate the problem of emitting GHGs, particularly the Co2 that causes drought, wildfires, and water shortages.

In many cases it is only through the wasteful practices of humans that water becomes scarce. Seventy percent of the water that is wasted in this world is lost through wasteful irrigation practices. Why then is it easier for man to expend countless hours and dollars in building these huge desalination plants that do nothing to replace the water lost and threaten the habitat of other marine animals, instead of simply looking to their moral compasses and conserving what we have?

Is it because we simply do not wish to admit that we are the cause of this crisis?



However, that is not to say that I am against desalination as a process when it is absolutely necessary to provide water to people, as in the case of the Middle East where water scarcity makes it necessary to emply such methods. I personally prefer geothermal desalination as the best method to protect marine life and cut down on carbon emissions.

This report from the Pacific Institute dated last year is a totally comprehensive and expert analysis of desalination globally and in the United States with both pros and cons explained in detail. There is no doubt that as we head further into the 21st Century in a world where water will be in greater demand desalination can be a part of a water management plan if absolutely needed (especially regarding using it in agriculture to conserve fresh water for human use,) but certainly not as the solution to this crisis and at the expense of other species and our environment especially regarding the clean up process. Only moral courage to conserve and to devise ways to use irrigation water more effectively and funds more effectively to shore up substandard water systems can we find the balance necessary to preserve all life.

[Trillo]

1. Low pressure solar still desalination is reportedly 90% efficient.

Here Comes The Sun: Engineers Develop Solar Desalination System
Filed under Research on Tuesday, September 16, 2003.

GAINESVILLE, Fla. — A solution to the growing need for fresh water in many parts of the world may come from a natural source: the sun.

Engineers at the University of Florida have developed a system that uses a gravity-induced vacuum and solar energy instead of electricity or fossil fuels to desalinate water. The system is significantly more efficient than previous solar “stills” for removing salt, yet is simple and inexpensive enough to be built in remote locations where conventionally powered technologies would be either too expensive or impractical.

“We know that nature uses solar energy to get fresh water from salt water,” said Yogi Goswami, a professor of mechanical engineering and director of UF’s Solar Energy and Energy Conversion Laboratory. “We use the same process as nature, except we enhance the process.”

A paper about the system by Goswami and a May UF doctoral graduate in mechanical engineering recently appeared in the Proceedings of the 2003 International Solar Energy Conference.

http://news.ufl.edu/2003/09/16/solardesal/

[RestoreGore]

2. How isit in conserving heat energy?

http://www.solar-desalination.com/

From the picture here it looks good and could be advantageous as a method used in Africa and other coastal water scarce areas where it would be necessary to do this at a lower cost. However, from what I read about it, much of the heat energy escapes as waste. I don't know if the newer methods have enhanced that process, but this is definitely worth looking at as an option too. Thanks for the link.

[nolabels]

5. The efficiency of energy use is always an issue with most any new invention

Excepting, of course, new inventions that save energy :shrug:

[Trillo]

6. I don't personally know,

I ran across that link a few weeks ago, and found it interesting because of the technique of raising the U-shaped tube about 32 feet to lower the pressure. With the evaporator at that location, the lower pressure helps the water to boil (evaporate) at lower temperatures. Wikipedia has two short articles on (generic) distillation:
http://en.wikipedia.org/wiki/Distillation
http://en.wikipedia.org/wiki/Vacuum_distillation

While Goswami says his system can be scaled up, in speaking of Goswami’s system, Delyannis claims, “But you have to keep in mind that all these systems are not compatible to conventional desalination plants of large capacity."

Myself, I'm quite certain there's a lot of political pressure to rationalize complex, energy intensive solutions to sea-water desalination. I've built my own RO units for a number of years (for my personal home use), and it seems there's a LOT of markup by some middle entities for various parts that need occasional replacement. The issue of salt water desalination by RO is that it requires a lot more pressure (and therefore energy) to push sea water through the membrane (versus already desalinated water which works well enough at 85psi). This means hi-pressure pumps driven by some form of energy.

Another solar technique that was developed at one of the universities a few decades ago used double walled glass tubes with a vacuum in between (like a vacuum bottle, but transparent), with water pumped through the inner tube. In sunlight it boils water because the vacuum between the tubes conserves the heat in the inner water tube.

Solar Distillation as a generalized desalination technique seems intuitively superior, versus Reverse Osmosis, to me. But business being what it is today, the costliest (greediest) solution is the one typically pushed.

[RestoreGore]

7. Thank you so much for this information

After reading it I also agree that solar distillation is a much more viable method. But you are correct in that the process that seems to ne the costliest is the one pushed, and in this case it also would be because it would fetch a pretty penny for the water consumed.

[karlrschneider]

3. The real solution is for us to learn to drink and/or live in salt water.

I'm only halfway kidding...just imagining -way- down the pike when the oil and 'fresh' water is essentially gone.
I can't imagine a several-billion population of homo sapiens existing in the year 3000. It just ain't possible.

[RestoreGore]

4. kicking because this crisis is more important now than yet another poll

Those who think the Internet will spark important discussions on blogs like this need to take another look. Perhaps those who run media conglomerates already have their minions out on these blogs innundating them with meaningless polls and threads that do absolutely nothing to further action on this crisis, but everything to perpetuate the same thing we see on our TV screens. It sure appears that way to me here and on some other blogs. I don't know, maybe if I had attached some political jingle to the end of this it would have gotten more attention. No wonder Mr. Gore is leaving the door just slightly open for a political future... he knows the mentality of those who absolutely must have that attached in order to care about anything else. It may not be exciting for some who only come here to discuss the "glamorous" part of their political fantasies, but if we as a people globally do not get truly serious about where we are going to get our water and how we are going to do it in years to come to maintain a sustainable balance, this crisis will definitely be a lot more than something to use on a thread along with "run____ run" to get attention. And people wonder why those who are serious about this lose their motivation to speak out.