How to Water the Desert
Intro: How to Water the Desert
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!
45 Comments
TudorS1 8 years ago
It is possible to boil water to the desert. If you use diagonal valves in the pipes the pressure of the expanding/heated water will push the water through the tubes.
And it is possible to heat the water in a cheap way..start with making the surface the color black...and there is a good suggestion in the book, without solar. See image. The pipes..well feel free to make the content of the book real. It does descibe a cheap way to make pipes....but..the question is still, if it is fantasy or real:).
Then again, it is always true that things need maintenance. Maintenance also means jobs.
Prof. A. Z. O_Trope 9 years ago
Unfortunately, you can only "pump" water a few inches this way, at best. Yes, warmer water will rise to the top of a column of water. But in a pipe open at both ends, once the overpressure created by the water above the source exceeds the total pressure at the source (~ 1 atm.), water will stop rising. When you do the math, even very cold water at the source vs. nearly boiling water at the top of the pipe will only allow the water to rise a few inches.
(If your source pipe was insulated and could extend to great depth, and you could heat ALL of the water in the pipe, you could do somewhat better, but heating water at the inlet of the pipe would be costly and difficult enough to outweigh any benefit.)
The other error here is the usual one with solar & wind power. Yes, the energy itself can be regarded as "free," but you need land upon which to place the collectors, and even more important, you need to BUILD the collectors, and that costs money (capital investment). Even solar troughs are not free, nor are long pipes, especially (as others have mentioned), pipes that will not corrode in hot seawater. And once the facilities are built, they will need MAINTENANCE -- they will get dusty, they will corrode, microbes & insects & birds & animals will do various things to reduce their efficiency, etc., etc.
There are some viable concepts in ocean-thermal and solar-powered water pumping and desalination, but this is not one of them.
TUYUQ 11 years ago
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.
wagon173 11 years ago
TUYUQ 11 years ago
mvillalpando 10 years ago
This idea can work, in sections, or fractals. If one were to incorporate Leonardo Da Vince's water pump instrument you may be able to do it in layers, or stages. See this link
https://www.lhup.edu/~dsimanek/museum/themes/pumps.htm
TUYUQ 10 years ago
I think taking the scale into perspective, the friction loss will be significant.
anyway I did study the salinity effects on the pipes in the parabolic through pipes and it will ruin the pipes in a very short time... however, I'm interested in this: http://en.wikipedia.org/wiki/Mangrove#Limiting_salt_intake , I think it could lead to something if we were able to proliferate it on a membrane or something and filter the saline water through it.
tokymaru 13 years ago
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.
diy_bloke 10 years ago
diy_bloke 10 years ago
wagon173 11 years ago
scienceguy614 13 years ago
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.
zombiefire 14 years ago
buteman 14 years ago
Sadly it will not lift water above the water surface by the method you propose.
lemonie 14 years ago
(Any thoughts as to why no one has done this yet?)
L
buteman 14 years ago
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.
lemonie 14 years ago
As I asked before: "Any thoughts as to why no one has done this yet?"
L
ironsmiter 14 years ago
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?
Alpha2904 14 years ago
masterochicken 14 years ago