Naked Science Forum
Non Life Sciences => Technology => Topic started by: myuncle on 08/04/2021 12:41:23
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For a river or aqueduct it’s simple to carry water, gravity is all is needed. But let’s say you want to transport desalinated water from the sea to the desert. If you follow the elevation map, you can basically transport desalinated water from the sea to virtually anywhere. They can use mirrors in a coastal area to heat the seawater, which will evaporate reaching high areas. Make huge funnels to collect the evaporation. And let gravity do the rest. If the pipelines are following the elevation map, water can easily travel anywhere, from Veracruz (Mexico) to Amarillo, from Guelmim area (Morocco) to Agadez (Niger), from Qabilat (Libya) to Ennedi area (Chad), etc., the possibilities are endless.
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Great idea, how do we get the power?
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Great idea, how do we get the power?
What you mean? Mirrors to heat the water doesn't need electricity.
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oops, you are right, to transport long distances, the angle would be 0.001°, basically a flat pipeline, so you need power to suck the water at the end of the pipeline. How much power you need? I don't know, have no idea.
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oops, you are right, to transport long distances, the angle would be 0.001°, basically a flat pipeline, so you need power to suck the water at the end of the pipeline. How much power you need? I don't know, have no idea.
On your question of power, wouldn't it be possible to make use of the Earth's axial spin?
For example, suppose we built a pipeline from Antarctica to central Australia.
The centre of Australia is sometimes called its "Dead Heart", because it won't support agriculture to grow living crops. Due to a lack of fresh water, to irrigate the crops.
Such water could supplied by a pipeline which starts at the centre of Antarctica. Which roughly corresponds to the. South Pole. Where the surface of the Earth rotates at minimum speed. And so its "centrifugal force" is at a minimum.
Then, you put Antarctic snow into the Antarctic end of the pipe. This results in the following consequences:
1. The snow in the pipe, gets impelled along the pipe by the increasing "centrifugal force" generated by the Earth's
increasing axial surface spin, as the snow is "flung outwards" to a greater distance from the South Pole.
2. As the distance from the South Pole increases, the snow gets warmer, and melts into fresh liquid water.
3. This water eventually emerges at high speed from the Australian end of the pipe. Where it's sprayed abundantly over the arid ground - to irrigate it, and thus create new, fertile fields for crops.
Sounds a good idea, doesn't it? Or does it contain a fatal flaw?
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oops, you are right, to transport long distances, the angle would be 0.001°, basically a flat pipeline, so you need power to suck the water at the end of the pipeline. How much power you need? I don't know, have no idea.
On your question of power, wouldn't it be possible to make use of the Earth's axial spin?
For example, suppose we built a pipeline from Antarctica to central Australia.
The centre of Australia is sometimes called its "Dead Heart", because it won't support agriculture to grow living crops. Due to a lack of fresh water, to irrigate the crops.
Such water could supplied by a pipeline which starts at the centre of Antarctica. Which roughly corresponds to the. South Pole. Where the surface of the Earth rotates at minimum speed. And so its "centrifugal force" is at a minimum.
Then, you put Antarctic snow into the Antarctic end of the pipe. This results in the following consequences:
1. The snow in the pipe, gets impelled along the pipe by the increasing "centrifugal force" generated by the Earth's
increasing axial surface spin, as the snow is "flung outwards" to a greater distance from the South Pole.
2. As the distance from the South Pole increases, the snow gets warmer, and melts into fresh liquid water.
3. This water eventually emerges at high speed from the Australian end of the pipe. Where it's sprayed abundantly over the arid ground - to irrigate it, and thus create new, fertile fields for crops.
Sounds a good idea, doesn't it? Or does it contain a fatal flaw?
I suppose the snow won't melt, clogging the pipe. It would be easier to melt the snow in Antarctica using wind power, then transport it.
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I wonder also what would happen if you place tall cranes in strategic points. There are tall mountains even in the desert, Mount Koussi in Chad for example is 3415 m tall. But probably the ice is not enough, and when it forms it stays in plateau areas, staying almost useless. Some of the tallest cranes are about 250m tall. Imagine you put a 500m tall crane on the top of Mount Koussi, you would reach 4000m, and probably ice formation would become huge and constant.
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Another idea: you tether flying fridges in the desert. Fridges are solar powered, and are obviously open, so the ice can drop down. You fly them using anything: kites, airships, hot air balloons. Everything is tethered to the ground. If the fridges make too much ice, they will become too heavy for the kites/airships. As a result things start going down, allowing the ice to melt. Once the ice is gone, the kites/airships will go up again, and the cycle repeats itself.
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Another idea: you tether flying fridges in the desert. Fridges are solar powered, and are obviously open, so the ice can drop down. You fly them using anything: kites, airships, hot air balloons. Everything is tethered to the ground. If the fridges make too much ice, they will become too heavy for the kites/airships. As a result things start going down, allowing the ice to melt. Once the ice is gone, the kites/airships will go up again, and the cycle repeats itself.
How do you get the water into the refrigerators so that they can make ice?
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The snow in the pipe, gets impelled along the pipe by the increasing "centrifugal force" generated by the Earth's increasing axial surface spin, as the snow is "flung outwards" to a greater distance from the South Pole.
- We normally measure height above sea level. Liquid water will flow naturally if it moves to a lower height above sea level, (with a slope of 1 in 50 or greater).
- The reason this works is because sea water already feels this "centrifugal force", so any flow possible from this mechanism has already been utilized by sea water, when setting the sea level.
- The same effect also affects rocks (but much more slowly)
- That is why the Earth's diameter at the equator is larger than the diameter through the poles, by about 40km
See: https://en.wikipedia.org/wiki/Earth
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Another idea: you tether flying fridges in the desert. Fridges are solar powered, and are obviously open, so the ice can drop down. You fly them using anything: kites, airships, hot air balloons. Everything is tethered to the ground. If the fridges make too much ice, they will become too heavy for the kites/airships. As a result things start going down, allowing the ice to melt. Once the ice is gone, the kites/airships will go up again, and the cycle repeats itself.
How do you get the water into the refrigerators so that they can make ice?
I don't know how fridge work, but doesn't a cold surface (drops on a cold coke can for example) collect water from the air?
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they can make ice?
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Mirrors, solar power etc will gather some energy, but to evapourate, condense and transport the quantities of water you are suggesting will require much energy. I should imagine that desalination plants are as efficient as can be at present.
The USA would be a good place to start, after all they are rich and have deserts that they try to irrigate.
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On your question of power, wouldn't it be possible to make use of the Earth's axial spin?
For example, suppose we built a pipeline from Antarctica to central Australia.
No. To a first approximation the Earth's surface is basically an equipotential, the crust sits on a liquid core, so it tends to slide around to even out the potential energy everywhere, and the sea does something similar. There's an equatorial bulge due to the spin, and that's why.
You have to rely on variations of the topography away from mean sea level.
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There is one interesting idea raised here.
Water vapour is less dense than air.
If you had a pipe from the coast to the arid region you could allow water vapour to run up the pipe, and then cool it when it got to the place where you needed water.
It's usually cold at night...
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I don't see that cooling is much of a problem. Indeed, a major issue would be the walls of the pipe would tend to condense the water vapour, so, much of the water would never make it to where you want it. You'd have to insulate the walls of the pipe up to the highest point to maximise water transfer. From there it will naturally condense and you could rely on the condensate flowing down hill.
The real problem is that water has a stupendously high latent heat of vaporisation. You'd probably have lower system costs to just run a desalinator and a pump, otherwise the heat exchanger to take the sunlight and evaporate the water is likely to be extremely expensive.
edit: I suppose really you don't need mirrors, you just need solar thermal collectors, like people put on their roofs to make hot water, a few square kilometers of that, and some pumps to circulate water around to get rid of the salinity.
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Free desalinated sea water is called rain. The trick is not to live where there isn't any.
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Free desalinated sea water is called rain. The trick is not to live where there isn't any.
On a per capita basis, that precludes living in the SW of the UK.
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Somerset >1500 mm per annum/956,000 . Cambridgeshire < 600/847,200, roughly half the per capita rainfall of the southwest.
But overall, it's pretty comfortable everywhere.
The trick is to use appropriate agriculture, as has been done for the last several thousand years: dairy to the west, arable to the east, and sheep where nothing else works..
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Free desalinated sea water is called rain. The trick is not to live where there isn't any.
On a per capita basis, that precludes living in the SW of the UK.
I should, of course, have said "bits of the SE of the UK". (It was late...)
Somerset >1500 mm per annum/956,000 . Cambridgeshire < 600/847,200, roughly half the per capita rainfall of the southwest.
Thanks for that, now, if you could do the same calculation for Greater London and, as an example of somewhere quite dry, Arabia.
You may find this data on population density helpful
http://www.citymayors.com/statistics/largest-cities-density-125.html
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Of course you could utilise the steam contraction and cold night time desert temperature of the desert. That would be convection.
To make it work you would need a large volume to provide the piston. Desalinate by the ocean using the sea as coolant, put it into a tank , have the contraction tank in the desert full of steam and hopefully by morning you would have fresh water. The volumes needed for large agriculture would not be feasible though, even the Colorado river is defeated by the sheer quantity needed.
Heat exchangers desalination plants, solar and pumps would be far more rational.
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I like the idea of using solar heat to vaporize salt water, and using the column of steam to transport it up to your pipe system (at altitude, air is naturally cooler, and will help with condensation). As mentioned insulating, and perhaps even heating your stack will also help.
Your condenser may also be able to be designed to pull a vacuum. It will need a temperature differential, but might be able to reduce the heat of vaporization (and reduce parasitic condensation).
Your problem would lie in routing the pipe. So, if you were pumping from sea level in California up to Colorado at about 1 mile high... that would be an awfully tall aquaduct.
And, of course, it would need to be really big. A pipe a foot or two in diameter would be ok for drinking water for a small town, but would barely water a small pasture for agriculture.
So, if you're thinking of an agriculture aquaduct, perhaps a pipe 30 feet in diameter or 10 meters... which would be a lot of water and energy for evaporation. And even that much water could be used up pretty quickly.
Now, there are a few things you could do to help the problem. So a coastal mountain range might help you gain elevation for both cooler air at elevation for condensation, as well as helping gain elevation/pressure for distribution.
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One point that comes up with some of the previous comments is that one often thinks of a closed system employing pipes and canals.
But, if one had predictable wind circulation, one could also do a completely open system.
Evaporate the water at sea level, and let it naturally gain elevation and condense out as rain. One might think of this as bad heating ocean water, but if one concentrates solar energy, it might have a net benefit of transporting energy into the upper atmosphere without a net increase in open sea water temperature.
Essentially just improving on Mother Nature.
The problem is that many deserts have a lack of rainfall for reasons that would be more difficult to overcome. Thus we have the largest rainforests surrounded by deserts.
Here we talk about rainy Oregon, but that is primarily a single valley. The Cascade Mountain Range has the effect of trapping and condensing moisture in the air and giving lush green farmland to the West and desert to the East. The weather is also very seasonal here, and global warming could impact our "dry season".
It may be that there would be some coastal areas where one could build rain evaporators that would be less affected by winds out in the middle of the Pacific and Atlantic.
Nonetheless, to make a dent in rainfall, such a system would have to be HUGE.
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There have been some studies indicating that trees, and in particular rain forests can help shape their environment. Essentially transporting surface water into their leaves and needles to promote evaporation which then falls as rain elsewhere. So, an attempt to help recover desert may involve selecting trees that might increase humidity.
I was considering salt water trees recently, and the most prominent salt water trees are in the Mangrove family which in theory could help desalinate water, and promote evaporation of salt water.
Perhaps it is something that should be promoted along beaches and canals in desert regions with adequate temperature to keep the alive. With, of course, the risk of them getting out of control. But, they could bring in multiple environmental benefits.
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One point that comes up with some of the previous comments is that one often thinks of a closed system employing pipes and canals.
But, if one had predictable wind circulation, one could also do a completely open system.
Evaporate the water at sea level, and let it naturally gain elevation and condense out as rain. One might think of this as bad heating ocean water, but if one concentrates solar energy, it might have a net benefit of transporting energy into the upper atmosphere without a net increase in open sea water temperature.
Essentially just improving on Mother Nature.
The problem is that many deserts have a lack of rainfall for reasons that would be more difficult to overcome. Thus we have the largest rainforests surrounded by deserts.
Here we talk about rainy Oregon, but that is primarily a single valley. The Cascade Mountain Range has the effect of trapping and condensing moisture in the air and giving lush green farmland to the West and desert to the East. The weather is also very seasonal here, and global warming could impact our "dry season".
It may be that there would be some coastal areas where one could build rain evaporators that would be less affected by winds out in the middle of the Pacific and Atlantic.
Nonetheless, to make a dent in rainfall, such a system would have to be HUGE.
The good thing about desert greening, is that you need just a bit of fresh water to kickstart, you are not obviously going to plant thirsty almond trees. And once the forest is made, it will create its own climate keeping moisture and creating even rivers.
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Maybe if you had some solar thermal collector on the sea, and then lead the water vapour up the west side of an Atlas Mountain with what was basically just a big black plastic bag tube. It would fill up from the water vapour, which is after all, lighter than air, kinda like a tethered hot air balloon, but you tether it to the side of the mountain and let it carry the water vapour over the mountain.
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You may find this data on population density helpful
Population density is the one ecological variable over which we have absolute control. We should use that control, rather than muck about with the environment.