Some serious questions need to asked about energy efficiency regarding different desal processes.I hope someone here in Oz takes the (patented) ball and runs with it.
(part of story)
"For a large number of saline solutions, eutectic freeze crystallisation is the most energy-friendly method of separating salt from water. It offers extremely high levels of purity of the end products, and avoids negative side effects such as poisonous fumes. Overcoming the many technical problems has been small beer compared to the fight Witkamp has had against the preconceived idea that processes requiring refrigeration must by definition be expensive ones. However, the experiments confirm the calculations, and provide incontrovertible evidence that EFC requires 30 to 70 percent less energy than evaporative crystallisation. It’s a cold fact."(see article)

http://www.delftoutlook.tudelft.nl/info/index2353.html?hoofdstuk=Article&ArtID=2764

One significant obstacle to its use is identified in the introduction:

"Efforts are now focused on scaling up the technology which has meanwhile been patented."

To the extent that Australia needs to address metropolitan water shortages now, it cannot use technology that has not been proven on an industrial scale.

I am somewhat puzzled by the article's comparison of efficiency with evaporative crystallisation, but with no mention of its comparison with reverse osmosis.

Sylvia.

I have read the article and enthusiastically went Wiki. No info?
Can someone suggest to an interested old fella where I might read more?
The previous post no doubt lucid did provide no info of the kind I need.
fluff

or we could stabilize population at 10 million and not need desal at all. but i suppose common sense is out of the question?

Thank you for the link, eftfnc. Good to see that there is a realisation that there are alternatives to high fossil fuel sourced energy inputs into desalination.

Sylvia has rightly pointed out that a proven industrial-scale application is that of which Australian water supply authorities have, in the self-imposed short-term necessity situation in which they now find themselves, the need.

The other aspect of the method mentioned in the introduction is its proprietary nature. Such tends to carry with it a predisposition toward such technology only finding application in privatised water supply regimes. You will note I do not mention a situation of free competition in supplying water, but one in which government regulated monopoly is the environment in which the water supply utility operates. This would tend to make such proprietary technology a natural ally of privatised water utility corporations, and the protected, priviliged investment opportunities they offer to institutional investors and financiers.

There are other non-proprietary technologies that, whilst they may have high energy input requirements, are technologies very well matched to various sustainable natural energy sources. It may well be these technologies that represent the best value to Australians at large in maintaining the quality of life to which most aspire.

Sylvia's salt-powered desalinator may be one of them. See:
http://forum.onlineopinion.com.au/thread.asp?discussion=134#3364

Another may be Dr Alan Williams' reduced-pressure distillation model. See:
http://www.globalwarmingsolutions.co.uk/large_scale_solar_desalination_using_multi_effect_humidification.htm

Yet another avenue may lie in the direction of waste heat utilization from existing coal-fired electricity generation plants associated with reduced-pressure distillation. You should look at the proposal for the application of this combination in SE Queensland. See: http://forum.onlineopinion.com.au/thread.asp?article=5616#75748

Quite apart from any stabilisation level for population that may be considered desirable, the fact is that the known variability of rainfall all over Australia places a premium upon the usefulness of desalination given its independence from rainfall conditions. So too does pronounced urban population concentration.

EFTFNC:
I understood the cheapest method of removing salt from seawater was pumping the salty water through a membrane under high pressure. This involves a lot of energy and a large de-sal plant would require its own power source or dedicated power station. Sydney water and Perth water claim energy costs are about $1 per kilolitre (1000 litres). Someone may have better informed or more current figures, if so I would like to hear them.