Solving Our Water Problems - Desalination Using Solar Thermal Power

There were a couple of small Australian solar power projects that I left out of my look at solar thermal power a little while ago, as I thought they were worthy of separate consideration.

I talked about one of these - Wizard Power's technique for storing energy using ammonia - last week. The other project is by a company called Acquasol which is building a plant to desalinate water using solar thermal energy at Point Paterson, near Port Augusta in South Australia.

Like Wizard Power and Lloyd Energy's graphite based energy storage technique, Acquasol received an initial round of funding from the (now defunct) Australian Greenhouse Office's Advanced Energy Storage Technology program.

In this post I'll look at the Acquasol project and then more generally at water scarcity worldwide and some of the approaches being taken to tackle it.


Port Augusta is a particularly suitable location for producing water via desalination, given its increasingly arid climate and remoteness from fresh water sources. Using solar energy to drive the desalination process is efficient for a number of reasons.

Firstly, South Australia is an importer of electricity and suffers occasional supply shortages in summer when the interconnectors to the national grid reach their limits. Secondly, producing water locally saves the energy currently used to pump water several hundred kilometres from the east of South Australia, where the increasingly scarce water is located.

South Australia also has excellent solar insolation, and the location chosen is close to existing power lines (for the Northern and Playford brown coal-fired power stations nearby), water pipelines and salt pans for solar brine harvesting.

This minimises a lot of the infrastructure costs and also enables a drawback of desalination plants (the environmental impact of discharging briny water back into the sea) into a potential positive, as it can be used to feed a salt production process instead.

The Acquasol plant will be producing water using a desalination process known as "multi effects", driven by 1.75-kilometer square concentrating parabolic trough mirror field. The desalination plant, solar thermal storage (apparently using molten salt, but this isn't clear) and other operating equipment will be sited in a small area adjacent to the solar field.

Multi-effects evaporates salt water using a vacuum and recondenses the vapor into drinking water. Both require energy, usually between 2.7-4.5 kilowatthours per kilolitre (though improvements to the technology are expected to lower this figure - hopefully to around .7 kilowatthours per kilolitre). At present, pumping Murray River water to the Upper Spencer Gulf consumes up to five kilowatthours per kilolitre. Multi-effects deslination can also use heat as an energy input, skipping the initial conversion into electricity and increasing efficiency.

The company expects that by having reverse osmosis desalination and multi-effects desalination operate side-by-side in future, powered by solar energy and incorporating thermal energy storage and a backup gas turbine backup, further operational efficiencies can be reaped that lower costs.

The water produced could also be in demand from large water users inland, like BHP's Olympic Dam mine, which currently draws around 30 megalitres of water per day from the Great Artesian Basin, and will need another 120 megalitres per day to service the expansion of the mine. BHP are currently proposing to build another desalination plant at Port Bonython near Whyalla, though this is being resisted for a number of reasons, one being a vulnerable local population of giant cuttlefish.

Another Australian experiment with desalination using solar thermal power is being performed by RMIT at Pyramid Hill in Victoria - this seems to be completely independent of the Acquasol project.

The Trouble With Water

Australia's troubles with water are well known by now, thanks to our recent bout of intense drought and the impact this has had on agricultural production and subsequently on a number of global commodity prices - rice being the most recent example.

The United States has also started to experience issues with water supplies in both the south east and south western states.

Access to fresh, clean water has increasingly become an issue worldwide in recent years, as a number of factors come into play affecting both supply and demand:

* Population is increasing - and most rapidly in drier regions
* People have become wealthier and accustomed to using more water
* Polluted water has become more common, as large swathes of the developing world industrialise
* Ever increasing demand for power (and newer forms of energy like biofuels or coal to liquids plants)
* Groundwater aquifers have been depleted by irrigation for agriculture
* The water industry is mostly made up of public utilities that have often been starved of new investment funds
* Climate change has impacted rain patterns, reducing rainfall levels and increasing the frequency and intensity of droughts
* Melting glaciers have reduced water flows
* Water has been cheap, so there is little incentive to conserve it

These issues have combined to make water a sensitive security issue in some regions, with some experts predicting resource wars over water, with obvious parallels to conflict over dwindling fossil fuel supplies (though thankfully water isn't actually depleting - it is more of a quality and availability issue).

Desalination Plants In Australia and Worldwide

In recent years a rash of desalination plants have been proposed for Australian capital cities to meet increasing demand for water and to insure against drought induced supply constraints.

* Perth led the way, with one plant already completed at Kwinana and another under construction at Binningup.
* Brisbane has built one plant at Tugun and is consider more at sites including Marcoola, Kawana and Bribie Island.
* Adelaide is building a plant at Port Stanvac
* Melbourne is building a plant at Wonthaggi, which is receiving a lot of criticism
* Sydney has commenced construction of a desalination plant at Kurnell, which has also been the subject of a lot of controversy.

Much of the criticism of desalination plants centres around their key drawbacks - they use large amounts of power (ex-NSW Premier Bob Carr used to refer to water from desalination plants as "bottled electricity") and they can have a large impact on the local environment, with danger to wildlife from the inlet valves and from the brine that is pumped back out.

The Acquasol venture stacks up quite against other plants well based on these concerns, as it uses locally produced renewable energy, doesn't emit brine and apparently has little local wildlife to contend with.

Another criticism of desalination plants is the high cost of building them, with water recycling, fixing leaking pipes in the water system and encouraging local rainwater capture (via rainwater tanks) often being deemed more cost effective and lower impact ways of providing more fresh water.

Nevertheless, construction of desalination plants has accelerated elsewhere around the globe as well, with prominent examples in Tampa Bay, Saudi Arabia, Abu Dhabi, Israel and Spain.

Desalination Techniques

The multi-effects desalination technique used by Acquasol is just one of a number being put into practice.

The other major mechanism is known as reverse osmosis, which is used for around 47% of installed capacity worldwide (vs 36% for multi effects).

A promising new technology that is being researched is the use of carbon nanotube based membranes developed by researchers at Lawrence Livermore National Laboratory, which they claim could reduce the cost of desalination by 75 percent compared to reverse osmosis methods.

Last year's "AlwaysOn Going Green 100" listed 19 companies concentrating on water, which demonstrates the level of interest in this area in the cleantech industry - though Neal Dikeman has cautioned investors that water is always the problem of the future.

Inventor Dean Kamen is another entrant in this area, promoting a relatively inexpensive small scale water purification unit which looks promising. A similar, but much more expensive, device is the solar cube.

Another interesting technique for desalination is the OTEC power generation process, which was discussed previously in my post on ocean energy.

Salt Power - The Power Of Osmosis

On a tangential note, there is an obscure alternative energy generation process known as "pressure retarded osmosis", which captures the energy that is released when salt and fresh water mix.

While this seems a far-fetched way of generating power (and I'm not trying to encourage any perpetual motion schemes involving desalination plants coupled with osmosis based power generation), there are efforts underway to explore the possibility of generating power in regions where large volumes of fresh water meet the sea.

The science behind these projects is based on the phenomenon that when salt and fresh water mix, they are typically warmed by 0.1 degree Celsius. Some Dutch scientists claim the total amount of energy generated at all the world's estuaries is equivalent to 20 percent of world electricity demand.

One trial is being undertaken at a fjord south of Oslo by Statkraft, the other at a seaside lake in Holland by the Dutch Centre for Sustainable Water Technology. Both schemes depend on membranes placed between the salt and fresh water - however the membranes are both expensive and energy intensive to produce, which means that power generation is not even close to being economical.

The membranes are, however, similar to those used in desalination plants that use the reverse osmosis effect - the market for which is growing at around 15% per year. General Electric is one of the major manufacturers and has an "aspirational goal" of producing fresh water from salt through membranes at a cost of 10 cents per cubic metre, with the hope of a new market emerging for power generating membranes a decade from now.

Modelling The Future

Returning to the original subject of Acquasol, one of the (non executive) directors of the company is Stephen Schneider from Stanford University - one of the contributors to the climate science blog Real Climate.

Schneider has an interesting column up at Edge magazine, which considers (amongst other things) the difficulties in modelling complex systems and overcoming political obstacles when dealing with environmental issues. While many of the remarks are aimed at climate science, I think a lot of them also apply to the issue of modelling and dealing with peak oil. The quote below is just a selection - I recommend reading all of it

I divide my life pretty much in thirds. One third is education, outreach, teaching, media, talking to Congress, parliaments, premiers, etc. and trying to get people—governments especially—to see this problem as it is and not as it's typically portrayed in the media, which tends to focus on the two extreme, lowest probability outcomes: 1. global warming is the end of the world or 2. global warming is good for you.

The second third of my time is spent trying to understand the science. When I talk about the science, I don't just mean answering questions like "how many degrees does the earth warm if you double CO2?" That's a very strict bio-geophysical question. I also want to know what happens to the water supply systems of the world if the planet warms by X amount? What would it mean to agricultural productivity, or to sea level, to the intensity of storms and how they impact people? I consider the study of the impacts of climate change just as much a science as predicting how much it will change.

The final third of my professional life—which involves value judgments as much as scientific and technological assessments—is spent asking the question: "What do we do about it?" That is, of course, a very difficult question because it involves inventing our way out of the problem on the one hand, but not waiting 20 to 50 years to do that on the other.

What is the sequencing of the so-called low-hanging fruit? The first step is performance standards for refrigerators, air conditioners, automobiles, machines and housing efficiency. That gives you a very fast payback.

Second step: public-private partnerships where we try to get the private sector to invest in the development and deployment of renewable and other low-carbon-emitting alternatives. They have return on investment criteria that are often too stringent to get a lot of the billions of dollars that need to flow into development, so we will need some federal, or state, and city financial pump priming, along with the bigger private foundations.

Third step: you can't keep dumping your tail-pipe waste and your smokestack waste and changing the land surface—all modifying the atmosphere—for free, as if it's an unpriced sewer. Sooner or later there has to be a shadow price on carbon. Whether it's a tax, a cap and trade system—somehow you have to make the polluter pay, and we have to take a look at the efficiency and effectiveness of those techniques.

But there's a component in this evaluation that I pay particular attention to that most of the economists do not. That is, if we increase the price of doing business by including a tail-pipe charge for our messing up the climate (and there should be one, because we are messing up the climate), the fact that it might cost me a thousand dollars a year in extra expenses might affect the quality of what restaurants I patronize and which grape I drink.

But, what will it do to a poor person? It might affect the quality of protein on their family's table. It's a dilemma. On the one hand you have a moral principle: the polluter pays. On the other hand, the relative fraction of my disposable income that that would represent is much less than that of a poor person in a hot country, or even a poor person in the United States. Energy costs are in that sense a regressive tax.

You cannot hold the sustainability agenda of the planet hostage to artificially low prices of commodities like food or energy, any more than you can allow what the first President Bush said at the 1992 Rio Environment Conference: i.e. "the American standard of living is not up for negotiation." In fact, if we're talking about poor people demanding equity, and therefore having per capita equality with us as polluters, we're talking about quintupling CO2 in the next century. That's unacceptable from the sustainability point of view. On the other hand, when we're saying that we will make the world safe for Hummers and SUVs at any and all costs, that's not morally acceptable either.

So the question is, how do you make deals where the over-consumers (us) work out a deal with the over-populated and the not yet fully consuming group (developing countries), so that they don't just repeat the Victorian Industrial Revolution with the sweatshops, dirty coal burning, internal combustion engine, etc.? The answer is that these economies in transition need to leapfrog right over it to high technology. Exhibit C: cell-phone. If you go into Central China, they talk to each other on cell-phones—well, so do we (we being the Europeans, Australians, Americans—the OECD type countries).

But how did we learn to communicate? We used mega tons of materials: copper wires, and we used energy to do it. China has not done that to our scale. Their cities are wired, but not the countryside. They literally leapfrogged over the Victorian Industrial Revolution to high-tech with regards to communication via cell phone technology.

We have to get them to do the same with primary energy and transportation, so that they can produce the kind of economy that gives them a decent standard of living without polluting the planet to a point where they and much of the rest of the world suffer a standard of living decrease. It can be done. It can't be done by China alone, or India alone, or us alone. But it can be done by good faith bargains—and that brings us back to that sine qua non—cooperation and skills-transfer. ...

I am not motivated in any of this by knowing the truth. I don't know the truth—nor does anyone else—about the future. What I teach, when I teach my Environmental Literacy course at Stanford, is to help confused students sort out how to tell this guy's claim from that guy's contradictory claim? I say, well, if a new dentist moves into town and hangs up a shingle that says, Painless Dentistry, what are you going to think? What about a new shop claiming to sell only Bargain Antiques? Or what do you think about a country that calls itself the Democratic People's Republic of Such-and-Such?

When the claim is in the title it's usually because the opposite is the truth. Check it out before buying it. You have to watch out for the myth-busters and the truth-tellers or the deniers of any risk or the ones who have absolute thresholds below which we're fine and above which everything ends—none of that is a very good description of our more probabilistic knowledge of future events and concerns.

What we know is that the warmer we get the more we add systems at risk and the more intense the impacts. We know that we need to slow down the rate at which we increase that risk without having to know precisely where these many impacts thresholds are, because they are not precisely knowable in advance. They are experiments we're performing on Laboratory Earth and—as I said in my book of that title from 1997—it is a "gamble we can't afford to lose".That's how I try to frame the problem.

I was told by an environmentalist the other day that using the language of tipping point phenomena (i.e. we must move now or we'll be irreversibly lost) is a good way to get people's attention. I said, well, that may be true for some phenomena but we don't know where the points are. We can guess, but what if we're wrong? What if we say that we have ten years and we don't do much? If nothing much has happened in 10 years, what then? Another tipping point 10 years later? People are going to remember what you said 10 years ago and your warnings are going to carry less and less weight and your predictions less credibility.

We live long enough that you have to be able to answer for your predictions. I much prefer to say that it just gets increasingly difficult to deal with the more and more warming we keep adding to the system. As with environmental literacy, watch out for the myth-busters, the truth-tellers, the ones with the simple answers from either side. You can almost always believe more somebody who's talking in ranges or subjective probabilities or bell curves, but at the same time isn't shy about saying that there's some real risks out there we need to mitigate.

Another reason I have opposed the "ten year framing" is the possibility that society will go on with business as usual and do nothing much. Then what? Do we say in ten years all is lost?? That is very counterproductive—what I call the On the Beach mentality after the Nevil Shute novel that was made into a movie. In it, the radioactive cloud from the nuclear war in the north is moving to Australia and they have months to live. Given that final inevitability, why not go out and race your car and go for derring-do of all kinds and get killed having fun? You're going to be dead anyway soon enough, and radiation sickness is a horrible death.

But that's not the right metaphor for climatic thresholds. Every single thing we do that slows warming down is better than doing nothing. But even if you fail to get adequate measures implemented soon, you don't give up, you keep trying to prevent it from getting higher and worse. That's my style, and not easy to sell in a sound bite, but I think you have to tell the truth. To me we don't really know what the absolute thresholds are, so let's not gamble that we might get the most dangerous ones, not because we're sure, but because we're prudent.

As for the climate denialists, we've seen their kind before—and gladly they are a vanishing breed in both smoking and global warming, though a few prominent ones are still out there spouting. Just remember, watch out for the myth-busters and the truth tellers and listen to the careful ones talking in ranges and bell curves.

Cross posted from Peak Energy.

Some factoids about Pt Augusta. Firstly as Kiashu pointed out this is where drums of yellowcake from Olympic Dam are railed to Darwin perhaps so as not to upset Adelaide people. However the two power stations use an abysmal grade of coal that has been likened to to brown dirt. They have 30 year reserves that are railed down from north as the yellowcake passes it going the other way.

I've noted that the top of the gulf has near stagnant water with elevated salinity so swimmers float higher in it. Presumably it is also more alkaline with metal concentrations. Thus it may not be suitable for reverse osmosis hence this vacuum method. Point Bonython near Whyalla and the cuttlefish has normal salinity due to better circulation.

Lastly it's a good thing there's no energy and water crisis as I suspect that Pt Paterson, Petratherm geothermal and Wizard ammonia will still be at the 'gunner' stage five years from now.

Not sure what you mean by 'gunner' stage. Is that good or bad?


"Gunner" = "Gonna" = "Going to" (one day).

Personally I'm glad people are at least trying to do some of these things - its better than sitting like a rabbit in the headlights...

'gunner' = going to ie not commercial reality.

While I'm being sarcastic now as the years go by these experimental projects will have to deliver. I'm not saying they will never scale up to commercial reality but I'm saying we shouldn't wait and hold back technology that actually works. If they can get extra water and electrical power Olympic Dam will become the world's largest uranium mine. Rightly or wrongly that helps millions of people. You could argue holding back inputs helps conservation or renewables long term rather than fossil fuels. OK but argue along those lines, not that there are quick alternatives waiting in the wings. What doesn't work now may never work.

Are you saying you think solar thermal doesn't work or that desalination doesn't work ?

They both look pretty well proven to me...

1) Acquasol's process
If they can produce a kilolitre for 0.7 kwh they should take over the desal up the road a ways at Coober Pedy where water starts at $5 per kL for preferred customers. I suggest the mining or horticulture industries may not want this water if it is over say 50c per kL.
2) baseload solar
A poster on regular TOD suggested that baseload means producing a nominated output for 6000 hours per year. I'll believe in baseload solar when there is a plant that can output 500 Mw for 6000 hours a year at a wholesale cost of 10c or less per kwh.

Let's give til year 2013 for either of these targets to be achieved.

I think wholesale electricity from all sources will be above 10c per kWh by 2013 (even before a price on carbon). So solar doesn't need to get that lower than that to be competitive.

I've got little doubt that with a moderate price on carbon, baseload solar thermal will make economic sense before 2013.

Climate change has impacted rain patterns, reducing rainfall levels and increasing the frequency and intensity of droughts

Do you have a good reference for the idea that warming will lead to droughts? It is often said, but not as far as I can see in the official reports. I think one of the official reports says that 2/3 of the world will be wetter and 1/3 drier. I think a CSIRO one says it will be drier south of a line from Sydney to Perth. Modelling shows that, and there is some reasons to believe it with the westerly patterns that bring rain to the south being held closer to the pole.

In a normal way the earth is either cold and dry or warm and wet. The very stable warm and wet period of the last 7000 years is very unusual. I'm pretty sure if it gets warmer it will get wetter. if it gets colder we're in trouble. A good way to look at the previous climate is the rate of change of sea level. Here's a link to Dr John Church's sea level history since the previous interglacial: The last interglacial was slightly warmer and sea level rose more. Then it fell off a cliff -- sea level fell at 1cm a year which is a lot of ice building up every year somewhere. I'm interested in ideas about what would cause that. E.g. "The Arctic sea ice melted, then there was more snow across the North, then a big volcano blew, giving several dud summers in a row, then there was much greater reflectance and that snow never melted...". An explanation that worked with the models would be more convincing than one that didn't.

Obviously the effects won't be uniform across the globe (and saying that rainfall will reduce globally was probably inaccurate).

Regarding the increasing intensity / frequency of droughts theory, see these links (I think its fair to say that drought seems likely to increase in Australia and other mid-latitude countries, but not in the tropics) :

The [IPCC] TAR stated that it is likely there will be higher maximum temperatures and heat indices over many land areas, and reduced frequency of low temperatures, including frosts. More intense precipitation events are likely over many mid- to high-latitude land areas. Increased summer continental drying and associated risk of drought are likely in mid-latitudes. Tropical cyclones are projected to become more intense with higher peak winds and rainfall intensities. Other patterns of climate variability, including the El Niño-Southern Oscillation (ENSO), may vary in intensity and frequency, with some climate models suggesting more El Niño-like average conditions, and others no change.

There is one interesting technology that has not been mentioned yet. That is the seawater greenhouse.

It is a combination of a greenhouse using seawater and some surplus on desalination. This is much more efficient than using standard desalination in combination with irrigation. It only requires a greenhouse, some plastic pipes and some solar cells to power the fan and pumps.

They also propose the aqua theatre on Gran Canaria for desalination:

A combination of cold deep ocean water, hot air and wind.

That looks pretty interesting - thanks for pointing it out.

Some more reference material for the Seawater Greenhouse can be found at

Some videos are available at

Sorry for being so brief but I type this in a phone.

Cheers Bjelkeman

I would love to see an analysis of desalination vs water purification and reuse. That is, is it cheaper to take water from sea water, or take grey water and black water and purify it and reuse it.

Xenon is now a division of GE. they are a Canadian company who has perfected purification via membranes. Very low cost and highly effective. They got all the bad press in California with the "From Toilet to Tap" label and big negative public outcry.

The founder of Xenon is being awarded the first "water award" (i don't know the proper name - its the name of the founder of Singapore) by Singapore for his technology innovations

Xenon is now a division of GE.

I'm sure I speak for several of us here when I say, I'll miss the chemical element. I don't know ... sometimes these companies seem a little ... a little high-handed.

... they are a Canadian company who has perfected purification via membranes. Very low cost and highly effective. They got all the bad press in California with the "From Toilet to Tap" label and big negative public outcry.

The founder of Xenon ...

Andrew Benedict (he was on the radio the other day).

is being awarded the first "water award" ...

How shall the car gain nuclear cachet?

I'm going to go out on a limb here and sans google, assert that if desalination (esp. reverse osmosis) was actually cheaper than standard water treatment procedures it would already be more widely used and the technology used instead of alum/ferric addition followed by sand filters (and maybe activated charcoal and chlorine/ozone).

I suspect that using reverse osmosis to treat grey water would take a lot less energy than treating sea water for the simple fact that sea water has 35 g/L of salt and grey water does not.

I suspect that using reverse osmosis to treat grey water would take a lot less energy than treating sea water for the simple fact that sea water has 35 g/L of salt and grey water does not.

Absolutely. The pressure required to force water through the filter in reverse osmosis increases as the salinity of the inlet water increases.

If you look at this article, you will see that if the salinity doubles in the inlet water, the pressure required to overcome this also doubles. This means that the energy required per unit of filtered water increases dramatically as the salinity of the inlet water increases.

All reverse osmosis systems release the inlet water as its salinity increases and replace it with water that is less saline - despite the loss of energy of doing so. Efforts are made to recover some of this pressure energy and to pass it on to the inlet water and some suppliers claim 90% recovery of this energy. It is little like trying to recover some of the waste heat of steam turbines and to use it to warm up the inlet water before it is heated in the furnace.

I have often thought that the mechanical engineering in and around ocean power, wave/tidal, should be focused directly on de-sal instead of generating electricity then driving de-sal process.

Oregon State University here is a considered to be at the center of wave energy development yet when I talked to several of the exhibitors at the last expo they acted like no one even considers anything other that the holy grail, the golden ring, the license to print $ that is generating electricity.

We need water more than we need juice.

It seems that the thinking in a lot of R&D, both public and private, is that it's all about the first person(s) to discover the "next big energy thing" will be rich and famous.

While that might be true, IMO we are wasting a lot of time, money, and brain power here when we could be building things that address the issues at hand.

souper- are you saying that water is the new oil?

Agreed - the combination of wave power and desalination makes a lot of sense.

I touched on a few Australian companies exploring this idea in my ocean energy post a while back (

Energetech / OceanLinx

SeaPower Pacific / Carnegie Corp

And the OTEC process also does desalination as a side benefit.

I'm not sure that wave power is that big a factor in the south of Australia, though I could be wrong.

What it does have in its favor is relatively warm water for most of the year. A far better combo (IMO) in that location would be to employ the Atmospheric Vortex Engine instead of waves to generate the required power. The AVE generates power by harvesting it from the Convective Available Potential Energy (CAPE) in the troposphere, which I suspect might be quite high in the region, especially during the summer.

In the case of multi-effect evaporation using concentrated solar, it would also be able to harvest the waste heat given off at 40-50 C at the end of the train.

For those of you who might be worried that this is another "Enviromission"--rest easy. Though it's based on the same principle, it does not require that a huge tower be built, that someday might be blown down, nor a huge "skirt" to trap solar energy. See for more details.

The southern ocean usually seems pretty rough to me, but some of the wave energy charts don't show it as unusually so.

The water there is quite cold (at least compared to the rest of the country).

I speak from personal experience, it is, or at least it can look that way from the deck.

Sustainablility Victoria (browser may need to be IE) has an interactive site for the Vic coast which shows parts of Tassie and SA. Once you get into Bass straight the wave potential goes down a bit.

It's hard to judge from the colour scheme but the chart indicates ~50kW/m from the Great Ocean Road (Otways) to about Beachport in SA.

Mind you, I have nothing with which to compare that number... is that high or low? (Apart from calculating that 20 km = 1 GW, if you could capture it)

Also, what is the practical upper limit. Ie you could site your infrastructure where there are very energetic waves, but that then increases the risks of loss and failure.

Is it that a more consistant intermediate "predictable" swell is preferred?

Thanks for a very informative post with lots of links Big Gav. Regarding the excellent except from Stephen Schneider, it is interesting that he does not mention Peak Oil or Fossil fuel availability as a concern or constraint. I suspect that many mainstream environmentalists have difficultly coming to terms with Peak Oil even though its timescale and effects are likely to be far closer than global warming.

With regard to Climate Change one only has to look at world sea ice distributions at the excellent website to realize the Earth is a complex system.

Arctic Sea Ice cover looks like it is following last years depletion pattern but the Antarctic sea ice cover shows a positive anomaly this year. Overall the Earth has a slightly positive sea ice anomaly right now. The Antarctic anomaly is likely just a statistical fluctuation for this year but it is as large (or larger) than any previous fluctuation over the past 30 years.

Well - James Hansen has considered peak oil - see his paper with Kharecha (sp?).

From the global warming point of view, peak oil isn't sufficient to keep us under 450 ppm (or even 1000 ppm) - there is more than enough coal out there to do a lot of damage.

So you'd have to assume industrial collapse as a result of PO before it makes any difference to the global warming guys.

In reality, I think PO makes the situation worse, as we'll see accelerating development of dirtier alternatives to conventional oil and natural gas - tar sands, coal to liquids, (stranded) gas to liquids, coal seam methane and whatever else we can (shale and methane hydrates potentially, if anyone can make them work) unless we make a conscious effort to switch to clean energy. And that means emissions will grow faster than ever...

As you say, the climate is a very complex system, so its very difficult to predict what the impact will be - which is why I think its best to invoke the "precautionary principle" and stop conducting a gigantic science experiment on the atmosphere and then seeing what happens.

For the paper by Pushker Kharecha and Hansen see

I do not believe that Hansen attended the Houston ASPO but Kharecha spoke on Friday night at a poorly attended session with Dr. Rutledge of Cal Tech. After the session Kharecha was virtually ignored as many from the audience gathered around Dr. Rutledge to discuss peak coal

Either you're greatly exaggerating about that last part or you and I must have seen Kharecha at different times after that session, because I was among at least 10 people talking to him afterwards. He was certainly not ignored; we actually had quite a good discussion with him.

And Hansen definitely didn't attend ASPO. If he did, that session would undoubtedly have been better attended, and maybe the organizers wouldn't have relegated it to a Friday evening when there was a competing event!

Hmm well it's that he has written a very thoughtful piece explaining risk probabilities without discussing a huge potential input to the equation. Already the world price of Natural Gas is so high that Nuclear Power is a substantially cheaper alternative for electricity production.

Coal is following a similar trajectory.

I think he should at least consider it in such a general essay.

Dang, first liar ain't got a chance (Old Joke:) )

This outfit says they can DO IT for a Nickel.

When you look at the first image there are no cooling towers so the two coal power stations must expend a lot of effort pumping warm brine through that shallow salt marsh. Good thing that low quality coal is cheap and will probably will stay that way for a long time.

I guess that salt harvesting be regarded as a form of localised salinity mitigation. However on a global scale melting ice caps must be diluting sea water. Fast forward to 2050 and maybe desal, energy production and dissolved mineral extraction will all be done under the one roof. Either hi tech or if JHK is right it will be back to ponds made by hand from dried mud.

Context. We need to put things in context. An example.

Spain has under construction some 10 to 15 solar thermal plants, ranging form 10 to 50 MW.

The 50 MW solar thermal plants are becoming a standard.

They occupy about one square Km in Southern Spain and are basically of the cylinder-parabolic mirrors, with an axe in the focus through which oil is conducted to some 300 degrees Celsius to a molten salt huge deposit (special salt that is brought in some cases from as far as Chile) to get thermal inertia enough to power some 10 to 20 MW on more stable basis.

There are in this moment about 100 requests for licenses to the Government, for solar thermal plants, trying to take advantage of the favourable electric tariffs, under special regime. I believe this is the first country in the world in these type of plants, which in principle were intended to reach about 500 MW in the renewable energies plan. At least ten times more than planned have been requested license.

But going to numbers, a typical 50 MW plant will produce in the best case, 50*8,760 hours*15% load factor (including losses), some 65,700 MWh/year.

Assuming the best figure given by Big Gav of 2.7 kWh needed to produce 1 Klitre of pure water (1 m3), we can easily calculate that a 50 MW plant will be able to produce some 24 million cubic metres per year; that is, some 24 Hm3.

Well, if we go to 100 times this value (5 GW of solar Thermal installed power), accepting all the gigantic subsidies to the big solar thermal industry, we will be able to produce, assuming we devote all the 100 times 50 MW plants to this purpose, some 2,400 Hm3 of desalinated water per year.

The present consumption of water in dry Spain is at present as follows:

Irrigation: 24,200 Hm3 or 80% of total
Urban uses: 4,300 Hm3 or 14% of total
Industrial: 1,900 Hm3 or 6% of total.

Experts in Spain consider that these 5 MW plants cost around 4-5 M Euros per MW; therefore, each 50 MW is costing some 200-250 M Euros or 320-400 MUS$. The Spanish ambitious plan of some 5 GW of solar thermal will need an injection of about32 to 40 billion US$ for merely an 8 percent of the total water use in Spain. With the present trends of the typical 3% annual economic growth, we will offset this extra production of water (or electricity, or whatever we may produce) in just 3 years; much before we can accomplish the 100 solar thermal plants of 50 MW.

The promoters are building these plants because they all expect to receive from the special regime for renewable energies existing in Spain (at present, just for 500 MW, but with everybody praying to reach the dream of the 5 GW), some close to three times the prevailing electric tariffs in the open market (27 cents of Euro per kWh; some 43 cents of US$ per kWh), granted for the next 25 years with CPI updates minus 0.5 or 0.25 percent. Should the Spanish government revoke or repel this privileges, it should be interesting to know what is left when the straw is removed.

100 plants of 50 MW each will occupy 100 km2. One of the plants has had to remove some 60 million cubic meters of land, just to flatten the area. The maintenance is rather complex. It needs a back up system to avoid the molten salt to solidify (either electric wires or combined gas plants), when cloudy days + nights last than one or two days. It is still to be seen how the maintenance is carried out: the fluid flowing through the focus pipe is working at extreme conditions just below degradation. The expansion/contraction continuous processes of the long pipes and systems throughout the 1 km2 plant are still to be long term proven. The maintenance is done, as usual, with plenty of fossil fuels powered machines, as well as transport. The parts (mirrors) are either of aluminium or tempered glass, are very energy intensive. It has to be analyzed and to be seen if going to levels of 5 GW (or 100 km2) of land left without normal irradiance, if they are in the vicinity of each other, are not going to have secondary effects in local variation of climate (i.e. formation of clouds will be one of the most paradoxical ones).

Context. Place things in context and see where are we going. Technology is not going to save us, if we continue this path.

Pedro from Madrid

You would also need to provide water for cooling of the solar thermal plant, unless you go to the still more expensive dry-cooling technologies.

The only idea which might make a degree of sense in this thread is the seawater greenhouse.


You are right in your first statement. Solar-thermal, Central PV, Algae farms in the desert will all need substantial cooling.

I disagree with your second one, because the AVE is ideally suited to convert what is erroneously called "waste heat" into more electricity (~20% efficiency). The AVE could be used as a "bottoming cylce" for all of the above (actually refrigeration device) for "desert algae" to minimize water loss.

Check out the Business Case at to see how it can be employed in place of a cooling tower. Water requirements are reduced enormously. Read my endorsement which explains why using the cold upper troposphere as a "heat sink" instead of the desert floor "changes everything."

Those of you who keep overlooking this technology need to take a closer look, IMO, and see if you can come up with a legitimate (e.g., thermodynamic) reason why it "won't work". Nobody has so far. It will save everyone a lot of trouble in the long run.

(No strawman attacks on the Enviromission Project, please--I have tried to contact them several times to suggest they replace their tower with a much cheaper vortex, but it appears that they are also "not listening".)

You can build plants with dry cooling, and I am not familiar with the vortex system so can't comment on it.
I am also not an engineer, so must rely on expert comment from them on the practicality of such a system.
However, the extra cost of cooling is merely subsidary to the excellent cost figures given in the post to which I was responding.
If the cooling was free it still would not make sense to use solar thermal to desalinate seawater on any large scale.
The very efficient use of water in the seawater greenhouse project may make this an exception for the production of high value crops.

I agree that the sea water greenhouse idea seems like a good one--climate control and irrigation in a fairly passive manner. Seems it would have application in many "dry" coastal areas, like along the west coast of South America. Maybe install a "solar preheater" with storage for watering at night as well.

I intend to look into it.

I don't really see why you would need watering at night, but that may be just a product of my lack of knowledge about all things agricultural.
Even if you wanted around the clock watering, then it would on the face of it seem fairly easy to do, as presumably when you evaporate the seawater a portion of it could be diverted to a separate container and used later.
One idea that might be possible is to use this in conjunction with salt-tolerant crops to further enhance the economics by not processing all the water.
This site has some good articles on growing crops with minimal water use:
EcoWorld - The Global Environmental Community - Nature and Technology in Harmony

Here is one on seawater farms:

If the cooling was free it still would not make sense to use solar thermal to desalinate seawater on any large scale.

Here we go again - the usual unsubstantiated FUD.

People need water - it can be produced reasonably economically using solar thermal desalination - therefore it is practical. Any city facing declining fresh water supplies near the coast could use this technology. Case closed.

Dry cooling (for power generation) is also practical for that matter - though an irrelevant red herring in this case - the desalination process doesn't require cooling of any sort.

Big Gav,

IMO, you are being unreasonably categoric in your second paragraph. Of course people need water, but water for what purpose? If fresh water is unavailable, even for drinking, it is not unreasonable to spend the electric power, from whatever resource might be available to get it, be that through reverse osmosis desalination or other means. This is done in the Middle East, not only for drinking water, but for other household uses as well. But they have more energetic resources than most.

But people also need food as well as water. As Pedro from Madrid point out, the requirements for conventional irrigation, especially in a warm, dry climate, are enormously greater than are municipal needs. In the absence of extremely cheap electricity, it would not be economic to try an accomplish this on a large scale in such a location. Unfortunately, CSE has not yet proven, not is it ever expected to supply "cheap electricity", at least on a "stand alone" basis.

On the other hand, based on the design and experience in Tenerife, Spain, the seawater greenhouse idea seems to have been well proven for these types of climates. Not having to go through the electric generation/transmission/electric-motor steps affords enormous economic benefits as compared to the alternative.

In my view, even a modestly sized Atmospheric Vortex Engine would greatly enhance such an endeavor, since it could induce the required "air flow" through even larger spaces, without having either to install fans, or having to line up with a prevailing wind.

Given the geography of Australia, and the energy/environmental trends, I think it would be a grave mistake to overlook the potential of either of these technologies in planning for the future of Australia.

The science behind these projects is based on the phenomenon that when salt and fresh water mix, they are typically warmed by 0.1 degree Celsius. Some Dutch scientists claim the total amount of energy generated at all the world's estuaries is equivalent to 20 percent of world electricity demand.

Well, something here doesn't sound ok. Wasn't salth solution supposed to be endothermic? Eeven then, there is still some entropy change that can be exploited to transform heat into eletricity, but "20% of world eletricity" seems too low. Is that number relative to what can be gathered with a specific technology?

Q:  Why would an endothermic reaction go forward (ΔH > 0)?

A:  When the Gibbs free energy (ΔG = ΔH - TΔs) is negative.

There's a lot of entropy increase in the dilution of salt in a solution...

That is exactly what I said, thanks. The stated potential still seems too low... That is why I asked if it was relative to a given technology, and not the theoretical maximum.

That sounds like the author is repeating some sloopy journalism.

I thought the qualifier "Some Dutch scientists claim" was a fairly good indicator that I'd neither checked the number nor had a high level of confidence in it - and that I was, indeed, just repeating a claim published elsewhere.

Feel free to try to come up with an estimate yourself if you think this number is low.

Thanks for answering. I have some estimations I've made a while ago (even a lab demonstration of an eletricity plant from difusion - that would take 40 years to payoff in practice :), but I was (and still am) afraid I got something wrong.

My deduction (from the statistical physics definition of entropy) is that the amount of energy one can get from a given volume of fresh water is at most E < Δn RTV where E is the amount of prouced energy, in Joules, Δn is the difference on salinity (mol/l), T is the temperature (Kelvin) and V is the volume of fresh water (liter). That assumes that the ocean is infinite in size and that there is no enthalpy change (the proccess is endothermic, I think, but uses very little energy).

Now, from the Amazon river alone one can get an average of 216.342m3 of fresh water per second (source (portuguese)). Assuming a fresh water salinity of 5.8 g/l (very hight wild assumption), and ocean salinity of 30 g/l (just rounding), and assuming all that comes from NaCl (rounding again), there is a salinity difference of (5.8g/l = 0.1 mol/l; 30 g/l = 0.5 mol/l) 0.4 mol/l, so one would be able to take up to 215GW from the Amazon river alone.

From wikipedia, the world uses nearly 17 milion GWh of energy per year. That averages to roughtly 2000GW of power, so by my calculations, the Amazon river alone would supply up to 10% of world's electricity. Now, Amazon is huge, but there are other rivers out there within a order of magnitude from it.

I hope the cuttlefish appreciate all the human anguish over nearby development

Note that Points Bonython, Lowly and Stony are adjoining. I believe that is the standout site in Australia to build a 1000MW nuke since they need 690 MW for nearby mine power and desalination. BHP also has the cash and insurance cover. Perhaps cooling water from any thermal plant could be used as input to reverse osmosis process with some energy saving. I think the cuttlefish will cope. After all with GW the seas are getting warmer anyway but less salty.

How about the plant just runs outside cuttlefish breeding season ?

People just need to factor the intermittency of nuclear power into account when costing these things...

IIUC, squid swim up and down the water column in search of food.  How about the plant has two cooling inlets at different depths, and it draws from the place where the cuttlefish aren't at the moment?

Bonus points for pulling water from the lower nutrient-laden zones and bringing nutrients up where phytoplankton can use them.

Thanks for what looks like a very interesting blog to follow, being an old resource hound.
I saw the Perth seawater desalination plants mentioned in your article. Do you realize that rainfall histories down the line of Perth dam catchments shows that "There never was a rain shortage to justify seawater desalination for Perth’s water supply", see;
How and why did the WA Govt go to this hyper-expensive, high enviro impact response to a normal cyclic dry period in rainfall ?
Best wishes to you all