Seawater Greenhouses

geordief

Valued Senior Member
This was very new to me

https://www.bbc.com/future/bespoke/follow-the-food/the-people-creating-an-oasis-with-seawater.html

Greening the deserts is a fine ambition.This technology seems to have some wings.

I didn't read any obvious downsides in that article.I hope this technology is on the right side of history.

Pad and Fan technology

https://ag.umass.edu/greenhouse-floriculture/fact-sheets/fan-pad-evaporative-cooling-systems
I found this very interesting. The only bit that looks fishy to me was the throwaway remark that "any brine left over" is turned into salt. Any? There will be masses of concentrated brine produced by this process and it will have to be disposed of. If, as they say, they are not putting the concentrated brine back into the sea, then they will make a lot of salt. What will they do with that? It's dangerous stuff, from the point of view of living plants.
 
They could do fish farming.When I was in Norway ,near Kirkenes from memory we used to salt the fish ( mainly Cod ) by laying them out on pallets so that the "village elder" * could throw the salt over each layer with a wide shovel

They used to ship this stuff off to Nigeria and South Africa .

* just mean it was a fairly skilled job and he had it.
 
They could do fish farming.When I was in Norway ,near Kirkenes from memory we used to salt the fish ( mainly Cod ) by laying them out on pallets so that the "village elder" * could throw the salt over each layer with a wide shovel

They used to ship this stuff off to Nigeria and South Africa .

* just mean it was a fairly skilled job and he had it.
Hmm, but seriously, there's a big issue here. In the Persian Gulf the salinity is 4%. For every cubic metre of water fresh consumed by this form of agriculture, 40g of salt is generated. That will soon mount up. In desalination plants, they return the concentrated brine to the sea, which is OK so long as there is a enough coastal mixing to ensure it doesn't raise the ambient salinity in the local waters. But with a lot of this agriculture, there could be problems - or an awful lot of salt to dispose of in some other way.
 
Hmm, but seriously, there's a big issue here. In the Persian Gulf the salinity is 4%. For every cubic metre of water fresh consumed by this form of agriculture, 40g of salt is generated. That will soon mount up. In desalination plants, they return the concentrated brine to the sea, which is OK so long as there is a enough coastal mixing to ensure it doesn't raise the ambient salinity in the local waters. But with a lot of this agriculture, there could be problems - or an awful lot of salt to dispose of in some other way.
Couldn't be a game changer ,could it?

Might the prize be many times more valuable than the expense of dealing with that waste product?

And is the hope that these seawater production centres will create micro climates so that conventional agriculture would also have a place to take off?
 
Couldn't be a game changer ,could it?

Might the prize be many times more valuable than the expense of dealing with that waste product?

And is the hope that these seawater production centres will create micro climates so that conventional agriculture would also have a place to take off?
Well possibly it could. I don't dismiss it at all. I'd just like to know how they will deal with all this salt.

There could be some valuable elements and minerals in it, I expect, which would be economic to extract from a ready-made pile of salt, but wouldn't be if you had to concentrate it yourself. I wonder. Apart from Na and Cl there is a lot of Mg for instance, and some Ca, K and Br.
 
Well possibly it could. I don't dismiss it at all. I'd just like to know how they will deal with all this salt.

There could be some valuable elements and minerals in it, I expect, which would be economic to extract from a ready-made pile of salt, but wouldn't be if you had to concentrate it yourself. I wonder. Apart from Na and Cl there is a lot of Mg for instance, and some Ca, K and Br.
I saw Lithium and Cobalt mentioned in that article.

They sound valuable to me ,but I don't know much chemistry or economics.
 
There is also gold in them there waves
I just checked - and apparently there's also URANIUM in sea water! And lead! And fallout from nuclear testing in the 1950's! And mercury! And cadmium! And thorium!

People are thinking about piping TOXIC NUCLEAR WASTE into YOUR CHILDREN'S FOOD!!!!!!!
[/im off]
 
I saw Lithium and Cobalt mentioned in that article.

They sound valuable to me ,but I don't know much chemistry or economics.
I've read that section again. I now think this this guy is a bit scammy and the BBC has been suckered by his sale pitch.

Li and Co are vital for modern battery technology - so obviously very topical and trendy things to mention. The sources are few and far between and, in the case of Co, the mining takes place in often very unsavoury conditions, in poorly regulated countries. So it would be fantastic if we could get it from seawater if his process were to enable that.

However, the amount of Li in seawater is about 0.1ppm. So it would be 2.5ppm of the solid salt extracted. That's very low, but possibly not too low for some kind of separation to be possible. In the case of Co, it is 0.0001ppm in seawater, so 0.0025ppm of solid salt. So this looks like a bullshit speculation to me.

More importantly, he talks what appears to be crap about brine cooling being an alternative to returning the brine to the sea. But it obviously isn't. Brine used for cooling doesn't just magically disappear, whereas the fresh water extracted from the seawater does get lost continually, to the atmosphere and in the bulk of the growing plants. So there will inescapably be a buildup of either brine or solid salt. Using brine for cooling does not solve this problem. Nor is it obvious why brine is any better than seawater for cooling. Nobody suggests either temperatures close to boiling or to freezing would be required in the process, so the boiling point elevation and freezing point depression of brine, both of which he mentions as advantages, seem to be irrelevant to the operation.

So I'm afraid I'm now suspicious that this is being oversold in a misleading way. Unless I've missed something, which is always possible.
 
I found this very interesting. The only bit that looks fishy to me was the throwaway remark that "any brine left over" is turned into salt. Any? There will be masses of concentrated brine produced by this process and it will have to be disposed of. If, as they say, they are not putting the concentrated brine back into the sea, then they will make a lot of salt. What will they do with that?
Put it in a deep hole.

There are salt caves all over the world; plants grow above them just fine.
 
I'd still like to see the maths. The amount produced will be huge.
https://edition.cnn.com/style/article/uae-pavilion-biennale-sabkha-cement-spc/index.html

Does this move the story along?

"Dubai architects Wael Al Awar and Kenichi Teramoto have developed a cement inspired by the UAE's salt flats (pictured) and made from salt minerals found in desalination brine. Dubai has become a hotbed of architectural innovation."

Just saw this article on CNN.Seems related.

Might it solve the problem of potential salt waste if the Greenhouses took off?
 
https://edition.cnn.com/style/article/uae-pavilion-biennale-sabkha-cement-spc/index.html

Does this move the story along?

"Dubai architects Wael Al Awar and Kenichi Teramoto have developed a cement inspired by the UAE's salt flats (pictured) and made from salt minerals found in desalination brine. Dubai has become a hotbed of architectural innovation."

Just saw this article on CNN.Seems related.

Might it solve the problem of potential salt waste if the Greenhouses took off?
Possibly, though I'd like to see how good this cement is in the rain! (It does rain in the Emirates, sometimes, in the winter.)

At least this article acknowledges that generating masses of brine leads to a waste disposal problem, whereas your previous greenhouse man seemed to shrug the issue off entirely.
 
This was very new to me

https://www.bbc.com/future/bespoke/follow-the-food/the-people-creating-an-oasis-with-seawater.html

Greening the deserts is a fine ambition.This technology seems to have some wings.

I didn't read any obvious downsides in that article.I hope this technology is on the right side of history.

Pad and Fan technology

https://ag.umass.edu/greenhouse-floriculture/fact-sheets/fan-pad-evaporative-cooling-systems


A New Mexico biologist and coach has a theory that if this was done on a massive scale this could even lead to cooling of the climate?

Global Warming II by Carl Cantrell

“So how is our problem of continental drying causing global warming? It all has to do with vegetation and sunlight. When sun light hits a plant, it causes a process which we call photosynthesis where the energy from the sun light creates oxygen for us to breath, water for us to drink, and is stored as sugar for plants and animals to use. When the same sun light hits the soil, all of its energy turns into heat and is radiated back into the atmosphere, carried away by running surface water such as rain fall, is carried away to other areas by our winds, and diffuses down into the soil towards the earth's crust. All of this warms our planet increasing its average temperature.”

“Therefore, the less vegetation you have on the planet, the more sunlight is being turned into heat and the warmer the planet becomes. This is very critical because warmer and dryer winds dry out other land areas faster decreasing the vegetation on those land areas. Less humidity in the air also reflects less sun light back out into space so that more sun light strikes the earth and more heat is generated….”

“The truth is that you can do more to decrease global warming by just reducing the average temperature for the Sahara Desert by one or two degrees than if we humans completely quit using fossil fuels and returned to the cave….”

“So, how would you start working to resolve this problem? Easy, cool the deserts and get some vegetation growing on them as soon as possible. But the method is much more complex than that. You have to use the prevailing trade winds in relation to the deserts to get the best results as quickly as possible and it will be extremely expensive….”

“Then we build desalination plants along the coast near these water sheds and pipe water to the tops or ridges of the water sheds…”

“This will do a number of things. First, it will increase the moisture in the desert soil so that it will develop water tables and water will begin to run in the streams. This water will increase the amount of vegetation in the area and decrease the amount of heat being generated by sun light cooling the watered area and all areas down wind of the watered area. As more available water evaporates, it will cool the air and reflect more sun light back out into space cooling the area even more. Cooler and more humid air will have less of a heating effect on areas down wind and will reflect more sun light back into space in those areas cooling areas we won't be watering yet. Cooler and more humid air will also have less of a warming effect on our seas and oceans.”

“Rain water running off of cooler soil will decrease the heating effect on our oceans and our planet crusts which will decrease catastrophic storm activities for other areas and seismic activity for the entire planet. Also, returning more ocean water to the surface and aquifers of our continents will lower the sea levels providing more usable land for us to farm and build on.”

“With cooler desert areas and increasing vegetation, less water will evaporate from our deserts increasing the amount of surface water even more and increasing the amount of vegetation and animal life by huge amounts because deserts currently take up more than 20% of our land surface. Populations will be able to spread out and there will be less competition for existing land areas.”

“This strategy has to be done in steps with the first step being to begin slowing the rate at which our global warming is increasing. We need to focus on that until we have brought it to a point to where the temperature is not increasing any more and is reasonably stable. While we are doing this, we need to come to a global consensus of just how cool we want to cool our planet down to. If we cool it down too much, we will begin to have devastatingly harsh winters in large populated areas and even cause an ice age to set in.”

“Then we begin cooling the planet down to a point which will be most beneficial for all countries or the planet as a whole. We need to gradually bring the temperature down because there may be a lag effect in which the planet will continue cooling after we stop increasing our efforts to cool it off more. We may even want to stop cooling the planet once or twice before we reach our targeted temperatures to see if there is a lag effect…”


“We need to start working on this as soon as possible because, if the planet reaches a point to where it is warming faster than our technology can possibly stop or reverse this warming trend, then our planet is lost and all life will cease to exist on this planet within a relatively short period of time. We will need to start with the largest and hottest deserts because cooling them will have the greatest benefit in the least time. (Global Warming II by biologist Carl Cantrell).
 
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