Here’s how to bring fresh water to all of those arid places you keep hearing about on the news. This solution is simple and cheap enough that it could be built from parts from any hardware store and affordable in any country with a drought problem. Basically, you use the sun’s energy to both pump water from the sea and convert it into freshwater. It seems like most of the world’s water has salt in it, so we should use some of that.
Say you have a large otherwise useless plot of land, like the Sahara. By using the Thermosiphon principle you could pipe water from the ocean to the places that need it. Here’s how it works:
Step 1: The general idea
Hypothetically, you could pump seawater an infinite distance, given an infinitely long heat source. Next comes that infinitely long heat source cheap enough to drag across the entire Outback, which could be constructed from soda cans and glass panes.
Step 2: Heat Source
Step 3: Modifications to a Solar Trough
Generally, these systems rotate to follow the sun, but that’s expensive, and poor countries need fresh water. One way to make this hotter is to combine the greenhouse effect in order to trap our solar heat in the trough. Ever get in your car on a hot day and wish you could somehow utilize the heat difference between outside and inside? By laying a sheet of glass atop the trough, we can trap that heat, making our trough more efficient. Remember, we don’t need to boil the water, just attain higher temperature than the water before it necessary to generate flow.
Another solution might be to distort the shape of the glass into a lens. By making the glass get thicker towards the middle, we can further focus the suns rays and trap heat. Just like roasting ants with a magnifying glass!
While this will not be as efficient as a rotating trough, the longer you extend such a trough, say for a mile or more, then the more thermal energy will be transferred into the water.
Step 4: Converting to Freshwater
Once the water reaches its final destination, you need to remove the salt. The ancient and cheapest solution is to use a solar trough. For example, if one were to stretch out a trough such as this picture of a solar still over some miles, the freshwater generated could be considerable enough for agriculture.
Here’s how this proposition works: There is a reservoir of saltwater in the bottom of the still. As the Sun beats down on the still, the rays generate heat which is once again trapped inside the glass. As the saltwater in the reservoir heats up, the still becomes humid inside and freshwater condenses on the ceiling of the still. Being as this still is slanted, the beads of moisture roll down the ceiling and eventually drop off into our reservoir of freshwater.
In this solution, we crisscross the incoming seawater from our heat-pump pipe across the roof of the still. This accomplishes two things: One, the incoming water is cooler than the still, thereby giving our heated moisture somewhere to condense (picture a cold glass of water on a hot day.) The second is that it preheats the incoming seawater (via the sun) before dumping the seawater into the trough, which we want to be really hot.
Step 5: Testing the system
Apparently, a system similar has been proposed here.
I propose using copper tubes, slightly angled from a tub of water, and a propane tank underneath the tube for heat. I'll prime the tube and install a check valve to keep water in the pipe prior to flow.
I'll probably blow myself up or burn down my back yard, but I'm heading to the hardware store now.
Step 6: Final Thoughts
Once we have a constant supply of fresh water into our desert, we can start growing some groundcover. Apparently once you have a bunch of plants in an area, clouds are invited and rain becomes more common place. Check out this thesis, ADRECS, and this one, Desert Rose. Growing plants in the desert causes the soil to become enriched because the plants deposit nitrates from the air into the soil and the plants decompose further enriching the soil. Eventually, the soil is good for growing everything.
Even before you get to that stage, you have sun, dirt, and freshwater to grow plants. Drip irrigation or a rotating irrigator could work here. Still don’t feel like using pumps or fossil fuels for this project? This thing (picture of Ox) runs on the plants grown and can be used for moving that rotating and pumping water through that irrigator (pic of irrigator).
Use this invention if you live somewhere such as a small island with no fresh water, Yemen, the Sonora Desert, Australia… You’re otherwise useless land now has value!
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I live in Jordan, we are the 4th poorest countries on fresh water in the world, and we have only 2400 meters of sea exposed to us, and beside that shore, there is a 45 degrees Celsius (85% of the year) desert which is useless and has no life what so ever. if this is feasible it will change this country for ever.
the salt water alone would wreak havoc on the pipes, zinc would work out better, but maintenance would still be exhaustive and costly.
one break or leak in the line and you water source is gone at least until its fixed and flow is restored.
while it was a good thought, i don't think it would work out.
Try this: go to your sink, fill it up with water, next get a tube and dip one end in the water and have the other end go to the toilet or a bucket or something. Next, with the end thats going to the toilet or bucket, suck on it to create a vacuum force and then take your mouth of and have it point to the toilet or bucket. the water will keep going untll there's either nomore water or the tube is in air.
Sadly it will not lift water above the water surface by the method you propose.
(Any thoughts as to why no one has done this yet?)
L
The coffee maker works because the water in the bottom is boiled, the bubbles of steam rise up the tube with some water. The average density of the 2 is low so the steam lifts some water with it.
The diagram Postonic has drawn does not show the water at the bottom being heated at all.
The top of the pipe is open so no vacuum would be formed to lift the water out of the sea to continue the process.
If, in the pi;e, you had 2 non-return valves one below the point you heat and one above it then, if you cycle between heating and cooling the water between the 2 valves you would get a ( very ) small intermittent flow of water. The amount would equate to the difference between the volume of the water at the lower temperature and it's highest temperature less the difference in the volume of that bit of pipe at the 2 different temperatures. As far as I know it would not be easy to find some pipe which would allow this positive output.
As I said I really hope this is wrong.
As I asked before: "Any thoughts as to why no one has done this yet?"
L
And then the people at the other end of the pipe getting mad cause it's HOT water, and all they really wanted was a cold beer?
Other than this the irrigated areas would attract animals which humans will eventually try to exterminate.
The sahara is also an important source of nutrients for the rest of the planet. If you were to convert it into farmland the sand would not be blown around by the wind at such high levels and slowly starve other ecosystems worldwide.
Nature is a cruel and uncaring partner. Wild, unpredictable, and always trying to kill everything. 99% of species that existed are extinct, and pretty much all of that has nothing to do with humans (a few percent at most).
Infact, why not just use a nuclear reactor? Sea water could be boiled, creating clean water, powering generators, creating electricity. Even better, geo-thermal. Pump in pressurized salt water, it comes up hot and is allowed to expand, generators, clean water.... we are on the verge of being able to drill geothermal wells almost anywhere... why not to move water to the desert.
have you try to send your idea (concept) to someone highly placed in the "green party" of your country ? (sorry for my english, i'm french)
How about building a small scale model of this first and then take the lessons learned from this and apply it to a slightly bigger model. Repeat this procedure until you can be confident that your full scale design would work.
As far as contaminates, solar stills supposedly remove most contaminates. However, as cheaply as I plan on building this, contaminates will probably end my system and cause leaks.
The testing that you are describing is very dangerous.
Super heated / pressurized steam is nothing to mess around with. I would recommend taking a couple of classes in thermodynamics before even considering this experiment. I would also recommend some guidance from a person that is knowledgeable about pressure and steam. They would think of items that you probably have not even considered. It would be well worth the time and effort to consult an expert rather than getting a finger blown off or an eye blasted out.
Also read up on a pressure relief valve, This should be installed on any type of pressurized system.
You should also familiarize yourself with flash boiling.
http://en.wikipedia.org/wiki/Flash_boiling
L
L
Acres of desert in Saudi Arabia or the Outback are relatively cheap, as is this system, but combine both and the value would be much higher than either the land or the system by themselves.
Mark Twain "Buy land, they're not making it anymore."... fixed
First of the entire part of the pipe that goes across land would of course have to be black and maybe even have some mirrors directing sun onto the pipe to achieve maximum heat.
Furthermore the part in the ocean would have to be pretty far down to sufficiently cool.
Then I suppose some major calculations would be necessary to find the right size for holes on the land and sea end of the pipe to allow it to release some amount of water in the desert while using some of it to recycle more of the cold water up from the ocean end.
And to start the entire thing of I suppose you'd need some pretty big pumps to load the entire pipe with water the first time around...
I might be wrong but this is how I imagine it would have to be done.
How much will a mile of trough cost? 5250 feet of supports, reflectors, piping, glass/plastic...and upkeep for when the piping breaks or leaks or when bad weather hits it or someone wants to use the land under it for a road or steal some of it for scrap prices...considering that a desert is HUNDREDS of square miles and you would have to water a significant portion of it?
As Lemonie says, this is probably better as a forum topic, where you could discuss methods and technologies, maybe even get yourself sorted to produce a working prototype before publishing an actual Instructable.
If you could make it work, and you established your rights to the idea, you'd make a fortune!
Shame I don't have a small copper pipe to try the idea out with and see... :p