Aussies believe in global warming...

Despite what Pat has just said, you cannot blame all the problems on water management. There were attempts to better control water..

The Snowy Mountain hydro-electric scheme was built in the late 50's/early 60's to produce clean power, and divert the water from the east coast to the whole Murray-Darling system, via the Murrumbidgee. Now there is no water coming from the Snowy - in fact, they are experiencing issues with generating power because of the lack of water.

My family used to own a sheep and rice farm in the Murrumbidgee Irrigation region, and now this is almost a dust bowl. One of the major rice firms has had to close one of their plants because not enough rice can be grown due to the lack of water, so even the NSW farmers cannot get water.

 

Both your and Pat's points are not in opposition. Nature is always unleashing extremes somewhere, and when poor planning has been in place, everyone suffers. The trick is not to point fingers, but to apply the lessons quickly. In the US, Hurricane Katrina destruction in New Orleans is a very concise example of the same thing.

 

There are a couple of ways. There are also systems that pull water out of the air that are run by solar, but I don't know how they work. RenewableEnergyWorld.com has had a few articles over the last 2 years about those systems. They have been set up here and there in Africa, where clean water is often an issue.

 

I'm hopeful a method of solar distillation could be arranged that would be effective for a large city

 

The original market that LUZ (builders of the first nine US thermal solar plants) targeted was to do exactly this, use the output of solar collectors to drive heat driven processes, like distillation.

Water is vastly easier to store than electricity, so intermittent operation of the plant is easily handled and planned....and the chances of a distillation plant being too big is not going to happen anytime soon.

 

No, I wasn't thinking of using either electricity or mirrors. The whole thing is driven by direct solar heating to evaporate sea water. My original idea, looking back to the crude sketches I did as a teenager, was for a floating dome that would collect the condensate and pump it onshore with wave-driven pumps. Deeper water would be brought up to cool an interior metal surface for the vapour to condense on. I may need a few years of engineering school to perfect it. Either that or someone with more money than ideas who'd like to trade places.

 

heard a pretty good show about solar power in Cali desert being built and set to be online by late 2010 or 2011. it uses mirrors to concentrate the beams to heat up this liquid stuff to a very high temperature that runs boilers to produce electricity with steam. it also heats up enough of this oil-like substance that it can continue to produce power for up to 3 days after the sun goes down. specs are for over a GigaWatt during peak daylight, 200 MW during off-peak

now the cost of the plant is relatively small and the construction time is less than half of conventional power plants. its estimated that less than ½ of one percent of AVAILABLE land in the Mojave Desert would be needed to generate enough electricity to supply all of cali power needs.

like the US, Australia has a very valuable and UNUSED resource and that is space. tons and tons of available land sitting there that no one really wants or needs.

many environmentalists cry that wind, solar, geothermal, etc will destroy our natural beauty. well that is BULL. there is more than enough land in the US to go around.

its estimated that if we eliminated all the occupied and developed land, all the parks, reserves, wetlands, etc along with a buffer around them, eliminate all the habitats of certain rare species (all of which will die anyway if we continue to destroy the environment by burning fossil fuels BTW), etc...

then divide the remaining land by half (just in case we forgot someone) we would only need a fraction of one percent of the land left to build a solar array that would service the needs of the entire United States...

now, what would that cost?? about an 8 year oil bill. i be willing to bet Australia is pretty much the same

 

The nice thing about CSP plants is that the guts is a typical Rankine cycle natural gas plant. You can have CSP with molten salt thermal storage with NG backup for extended periods of low quality sunlight. My impression of CSP is that it degrades very poorly in the event of sub optimal sunshine. PV degrades a lot more gracefully, I think. The upside is that CSP is pretty darn efficient, considerably cheaper at scale, and allows for very efficient heat storage in molten salts (which are more efficient than batteries, and a lot cheap, I believe). I imagine that we'll see Oz tapping CSP for desalination. Perhaps some sort of concentrating distillation process.

 

Yes I agree

 

With what, laddie?

 

Your rant about CSP, molten salt, and desalination

 

I agree too, what ever you just said.
Could a CSP be placed along side a coal fired power station to supply steam to drive the turbines? This might allow a low cost conversion of existing plant. In South Australia the Port Augusta power station burns dirty brown coal and provides the lions share of South Australia's electricity. The power station is well out of town so is surrounded by desert land. Is there any reason the mirrors can't be placed over water?

 

No technical reason why not. You'd have to get creative with manifolds and valving to ensure constant flow, with backflow prevention, but entirely doable

No reason. You'd need a rigid platform as wave action may decrease efficiency.

 

What about a solar 'cogen' plant? Focussed rays could heat seawater into steam, creating electricity, and the condensate could be filtered to produce fresh water. Not sure what the market is for sea salt, but that's also a possible commercial byproduct. The efficiency of solar power plants isn't spectacular, but if the sunshine's free and so is the water, then maybe it's not so important.

 

Yes, that's a good point. Salt is a fairly common commodity, it has many industrial uses, far beyond something you sprinkle on your supper

Many platforms offshore could not only produce electricity, but potable water as well. It's a good idea

 

And if deeper, cooler water were wave-driven-pumped to the surface, increasing the temperature difference, would that increase the efficiency?

Is there any funky chemistry to boiling seawater, like strange gasses, or filters clogged with diatoms?

 

Like a Stirling Engine setup? Maybe. I'll have to think about that, preferably after 2-3 barley pops to lubricate my thinking machine

Organic buildup is always a concern with distilling seawater. By "filters" I assume you're talking about an RO process? The RO feedwater *must* be properly pretreated (Coagulation/flocculation, chlorination, etc) or the membranes will experience rapid biofilm fouling and clogging

Note: the feedwater must also be dechlorinated as most membranes are ruined by the levels of disinfection required to pretreat the seawater

If flash evaporation is used, you can expect better quality water, but somewhat lower recovery. Eg a properly designed desalination plant may expect up to 45% potable water recovery from seawater, though average flash evaporators may be as low as 10-15%

 

evaporators sound good and with cheap renewable energy the efficiency of the system is less of an issue. i would assume that even a large system would not change the salinity enough in the ocean, but what about localized salinity issues? how would the slurry be disposed of ?

many many many years ago, i saw a show (i am pretty sure it was a kids show) about a desalination operation that not only produced potable water but also several other useful products taken from the seawater... is that too much additional expense to investigate?

 

Wondering if salt from seawater has a market?
These are the salt pans at Dry Creek in Adelaide, the salt recovered here is used by Penrice Soda Products to make soda ash, which is an important ingredient in glass, and many chemical preparations. It is also used to make carbon dioxide for carbonating drinks, no I don't know how that works.

The salt pans are located about 15km from the heart of Adelaide and cover a huge area. What you see in the picture are the crystallisation pans, there is a chain of ponds and channels where the water is evaporated off. This is one industry that loves a drought!

Once harvested the salt is stock piled over a drained area where when needed water is poured through so the salt and water run into the drain from where it is pumped under the Port River to the soda ash kilns where in combination with limestone it is processed into soda ash.

At the other end of Adelaide the South Australian government is building a desalination plant!
You work it out.

Edit; More about the picture.
The salt crysallisation pans are the rectangles on the right of the picture.
The pans cover most of an area about 2.5 miles by 3 miles.
Some of the evaporation ponds can be seen toward the top of the picture from the evaporation pans.
The evaporation ponds stretch for about 20 to 25km to the north.
The port river is on the left of the picture, the pipeline crosses Torrens Island and the river.
The structure on the Southern end of Torrens Island is a gas fired power station.