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.

SILLE,

You have been given the answer in the link supplied above to Dr Alan Williams' web page. The information is in a section of the paper headed "Cost of Desalinated Water".

Dr Williams quotes a projected cost under a reduced-pressure distillation scenario of the order of $0.28/m3. A cubic metre is equivalent to one kilolitre. I remember reading somewhere in his paper Dr Williams warns that his cost estimates are all quoted in US $.

(Now there's a curiosity for you! The dollar sign was derived from the monogram for the United States, and hence the TWO vertical strokes through the "S" in proper representations of the symbol for the REAL dollar. And here I sit in front of a Microsoft keyboard that has a dollar sign with only ONE vertical stroke. That is the official symbol for the Australian dollar! Australia must be going to rule the financial world! Or at least Bill Gates must have thought so at some point. You saw it first on OLO!)

Dr Williams says, in this section that "The cost of desalinated water from the world’s most recent large plants is about $0.5/m3". He also says "The running costs of the solar desalination plant would be very low with its fuel free. This order of magnitude calculation indicates that large scale solar desalination could compete with present desalination technologies."

Have you ever risked standing for Parliament anywhere SILLE? You seem to have the prequalification of being unable to digest anything that isn't on one A4 piece of paper containing a lot of blank space. You need to read more widely, and for context, if you wish to avoid that fate!

Just to make it perfectly clear, I think when Dr Williams refers to "the worlds most recent large plants" he is referring to conventional fossil-fuelled distillation and/or reverse-osmosis plants. This is not what desalination is really all about. It is about true independence of both fresh water and energy supplies, particularly in countries like this. Wake up, Australia!

Any fossil fuel fired processes could most likely be replaced by a combination of wind,steam and bio-fuel power.Burning seawater thru RF is just around the corner with great potential for perpetuating energy.(see
http://youtube.com/watch?v=h6vSxR6UKFM
What I am sure of is that Australia with all it's bright minds is in a favorable position to come up with great solutions, and I don't mean just using or building on old ideas.

It is silly to go down the desal path until the amount we pay for water matches the cost of desal. Otherwise you are just subsidising the waste of a very expensive resource.

Freediver,

I have no doubt that the price we pay for water will rise to meet the costs of desalination. The price doesn't have to go up very much to achieve that.

At the moment we have an undesirable situation where people are restricted in how they can use water, rather than being allowed to use as much as they're willing to pay for, as is the case with other commodities.

Sylvia.

It has to go up a long way to achieve that. Desalination of seawater is rediculously expensive. Rather than building desal plants, we should just raise the price now. We should have raised the price a long time ago. It's the best way to discourage the waste of water. Unfortunately now we only even pay attention when the rivers have long been sucked dry.

Freediver

What do you think the price would have to be?

Sylvia.

Whatever desalination costs :)

For comparison, I think I am paying $1/kL 'retail'. Note that there are still farms using water that would otherwise be available to cities now considering desalination. So effectively you would be using one of the most expensive options available then tipping the water onto the ground.

According to this site, it costs $0.8 to $2.1 /kL (wholesale) for 'brackish water'. Desalinating seawater costs 3 to 5 times that much. Then you have to add on distribution and disposal costs.

http://www.crcsalinity.com.au/newsletter/SeaNews/dpap0102.htm

Suppose the price of water suddenly went up by a factor of 5 or 10 (a lot more for farmers I think). Would we still need new plants?

Freediver

I don't see where you conclude that the figures on that site are for brackish water rather than sea water.

This page

http://www.water-technology.net/projects/perth/

gives an estimated cost of desalinated water from the Perth plant of $1.17 per kl. Typically, in Australia, a desalinator is only providing a proportion of the water in a metropolitan area, so the increase per kilolitre in the tap is not $1.17 per kl, but rather less. For example, if a desalinator were providing one third of the total water supply then the increase in price at the tap would be one third of $1.17, or 40 cents per kl.

Sylvia.

"I don't see where you conclude that the figures on that site are for brackish water rather than sea water.

Because it says it quotes the cheapest overall price. You wouldn't base that on an option that costs 3 to 5 times as much. There are plenty of brackish water desal plants around, used by industry to provide high quality water.

"Typically, in Australia, a desalinator is only providing a proportion of the water in a metropolitan area, so the increase per kilolitre in the tap is not $1.17 per kl, but rather less.

The market price should reflect the marginal cost, not the average cost. This is basic economics. Would you make something for $2 then sell it for $1? Then maybe ask the people who can make it for 50c to bail you out?

Did you know that the price of electricity is going to go up due to climate change? This will push the price up. Desalination causes a lot of greenhouse emissions.

The price of $1.17 appears to ignore delivery costs etc and to be based on interest of 10% pa with no repayment of the capital. Even if we accept that, it is still above the retail price for households and way above what farmers etc pay.

In a totally free market (no barriers to entry, etc) with a completely homogeneous commodity product, the market price will be close to the marginal cost. This is an inevitable property of such a market, but that does not mean that that price is in some sense the 'correct' price. In practice, few markets are that homogeneous, and most things are not supplied at anything like marginal cost.

If water were to be priced at its marginal cost, that being the cost of desalination, then the water companies (which are proxies for governments) would be receiving incomes far in excess of their costs. The consumers would quite rightly take exception to that.

Given that most potable water comes from catchment areas, water supply is a natural monopoly, so free market mechanisms cannot function. The correct approach to pricing in such a situation is to determine a price that allows supply (rising with price), to match demand (reducing with price) without artificial constraints on consumption, such as water usage restrictions.

Sylvia.

This post limit is very frustrating. I posted my response to you here instead:

http://ozpolitic.com/forum/YaBB.pl?num=1166414069/33#33