hydro-electric in sahara desert

Interesting idea - but what do you do with the salt? There's an average of about 35g per kg of seawater - running enough water through your turbine to generate a worthwhile amount of power is going to leave a hell of a lot of evaporites.

There may be only a few catches.

The pit is made deep inside the desert (300 ft you say)

at 300 miles from coast - it is not a open channel - pl take care of the huge friction losses taking place in the pipe for carrying this volume of water and calculate the pipe dia and hence the cost.

The water soaks inside the sand till when ?

There may be subterannean water (and oil ) and slowly this gets filled up may be in a year or so - unlike the normal hydro turb- its drain is not a permanent one

The drying up - will take its own time since as you start pumping in water the ecology changes at least in the area and humidity shoots up thrugh the wet sand

Take care of the crumbling wet sand and sand storms

Not infeasible but not sure about the economics - solar could have been a far better solution for the area with year long sunshine.

This energy you can use for reverse osmosis of a mush smaller quantity of sea water to make it a potable water.

You see there is a flow, the flow takes place across a head (for you say 300 ft) when we talk about head - it is a pressure whether it is by gravity (height diffce) or by a pump

Once there is a flow, and for the turbine you do need a high flow, the head drops .

This is going to be an issue.

The question is not whether you have the deposit at 300 ft, at a certain depth you start getting bed rocks, even in desert (the sand is only a skin deep)

Just checked one article- as per which there was aplan to make an inland sea in sahara - which had an average depth of 78ft only. After this that means the bedrock starts.

Now if you dig out even at the max area and let it be 1000 ft, it will be at a valley - and after a certain months, your turbine will be flooded.

The desert heat/extreme dry wind will remain for a few years avter that as you bring in millions of gallons of water, the evaporation of it will be associated with humidity.

What you do need is an geological map of the sand bed depth, couldn't find it., This is the critical information. The sand can not be allowed to be soggy, at least fast or near by, the water flows out a bit far, no problem there. Let it be afforested there (where will the poor ostriches and desert lions go?>)

Read the history of the formation of the Salton Sea in southern California, USA by an unintentional flood for some insight into how a plan like this might play out. Wikipedia has a good writeup on the Salton Sea and if you use a search engine to search on the phrase "Salton Sea formation" you will bring up several other articles on the subject.

Ed Weldon

Also check - Long back read an article- French wanted to make a Sahara lake in place of Sahara Desert, mercifully they found the cost was prohibitive - or may be otherway round. Since we would have got all the dinosaur fossils long back - only might not have been intact (you know how the construction companies work )

Hello rmg21,

This sounds interesting if a little hair brained.

I assume these horizontal 'drills' can get through bedrock, 300 miles, 480 Kilometres?

Where are you getting the water from? You will need to rid it of salt if it is from the ocean. Otherwise you could be building one of the largest salt pans in the world, as the water evaporates?

Assuming it is fresh water. What are you going to do to stop the rest of the desert from soaking up this water?

I know there is a fresh water subterranean pipe which serves a whole lot of wells in a controlled way. It is quite small and designed at least a hundred years ago to supply drinking water. This was in a pipe and stays at a constant 5 to 10 Deg'. It is not draining into the desert there. It is controlled.

Have you done any measurements to see if there is a natural dish or bowl in the bedrock where you want to get the water to? What is stopping the water eventually flooding and washing away sand from the bedrock?

Is this just to generate power? I would have thought you needed a pretty good 'head' to power a turbine. Where is the head coming from, or should that be how are you going to build a head?

I will watch this thread as it sounds interesting. But at the 'back of an envelope' stage?

Good luck............................

I can remember the Israelis look at doing this with the Dead Sea a few years back. Tunnel from the sea to the Mediterean. No problems with the salt, as they could evaporate off the water from the brine, much as they do now. The salt would then be sold. currently due to salt recovery, the level of the Dead Sea is dropping. They would have to keep careful control on the scheme, but the power generated, would be considerable as well as "green."

Hello rmg21,

Do not take it as an insult OK? This is just my opinion.

I called it hair brained because it has not been thought through. It would be very expensive power. The 'pipe' could be open to attack and damage by whomever, just as the channel tunnel is. A hiccup like a fire, the equivalent of a bomb in your idea and the whom thing stops, and you did not mention the question about the salt.

Man made lakes are doomed to failure as they have a limited life. Unless you build an aquifer the evaporation has to be a serious consideration. If you do not and just let the dessert fill up with water would you not be able to stop the water from altering the source from possible damage.

The ecology of an area where you may choose to extract the water from relies on the circulation of water. Lake/river, evaporation to local mountains which means it rains and a circle of essentially the same water is sustained. The amount and potential 'waste' of the water this could use could end costing some other area substantially, in the water drying up and that in turn will become a dessert.

The possible way it may be feasible is if an underground water source if found which is not already being used. Forgive me but I cannot recall the name, but even huge inland seas can shrink to nothing if water is taken out faster than an area thousands of kilometres away can 'feed' the sea. The place I am thinking of is the Red sea I think. Dams and other use of the water feeding the sea have reduce the water substantially, with what were coastal settlements, not hundreds of kilometres from the water, and ships stand on the sand remaining as ghosts to a time that was.

It hardly matters to me as I am just a simple man. If it ever gets the go ahead it will not bother me because I will not be here. However, there is a reason why all the dessert areas of the world have Cities and settlements around the perimeter. They either rely on local fresh water or in extreme cases on desalination.

I think you should drill for water not oil, and do you not think if it was there, any water would have been found by oil prospectors?

You can't put part of an idea together and call it complete. The whole thing has to be able to be made and seen to be made to work.

This is truly a 'pipe dream' which if ever brought to fruition with kill another comunity.............In my opinion that it.

There is a lake in Wales in the UK where a power station has been built inside the mountain nearby. Water is pumped during the night using 'cheap' electricity, and used during the day to drive vertical turbines in the mountain. But that place has a natural water catchment, and it is recycled. I cannot see how your idea can recycle the water to the benefit of the place you build the power plant or, the place the water is sourced.

Maybe you could still do a similar thing but exclude any water pipe and instead use the pressure from an OIL WELL to drive the turbine?

Take care and good luck...................

...easy there babybear, my response was tongue-in-cheek!

how's anyone gonna get to a pipeline at 300' or more---in the ground?

and there are no tunnels...just naked pipes in the ground.

then again, the other supporting infrastructure would indeed be exposed such threats, but that's probably a different topic......

on the risk of shifting the desert to the water source, let's look at it this way;

we have x tonnes of water flowing thru' the river and into the sea.

what this plant needs is probably a small percentage of the river flow(which would flow into the sea anyway, as in 'wasted').

Ok, salt would be a problem if the ground below the pit is non-porous/permeable, and I'm betting on the great possibilty that the vast sahara desert offers a huge buffer to suck in all this water that flows into it.

and at the same time, the heat and dryness of desert surface should send a big chunk of the same water back into surrounding atmosphere, hence, altering area around it, i.e.: making it more humid/wet...with time, we should get some green back into those places.

Unless of course if some here feel that sahara desert should be maintained in its current 'pristine' condition!

so, only and portion of the drain water stays in the ground(will it accumulate over time...more homework needed), while the rest ends up in the sky. about the salt that stays behind........stay tuned!

and if the source is the nile or lake victoria, no salt issue.

were you talking about Caspian sea... yep, she's shrinking!

The Wales project is a fine example of pumped-up energy storage system.

conclusion:

1. if I use seawater from the nearest coast, and sahara couldn't suck it up, salt could be a problem. No effect on the source.

2. if river water is tapped, no issue for the source(river/lake)because only the 'overflow' portion of the river/lake would be used.

3. no community would be harmed in this exercise!

4. new civilisation might crop up in the middle of the sahara desert instead!

Hello rmg21,

I think firstly that I should say I in no way intend/ed to insult you!!!!

You must be a pretty good Engineer to even think of the possibilities!

I thank you for the reply post, although my personal opinion is it is either too costly, and or, a whole lot of thought has to go into this because something on such a grand scale, could also end up as the largest grand scale white elephant.

I thank you BTW for the reminder of the name of the shrinking sea, namely the Caspian. Sorry I started writing and it just completely went from my mind, thank you.

I am not saying you are a bad Engineer for thinking this up. Or that you are a stupid person. If such things were not aired, there would be no Panama Canal, no Airplanes, no gigantic bulk oil carriers etc, the list goes on.

Listen, please, I am not in anyway an expert on this. But from my noted experiences around the world where things have been a catastrophe because things were tried which, I admit in hind site, were never going to be successful. And please do not ask me to be specific.............I am talking and trying to sum up my life's experience so far, which included several things like the Caspian Sea shrinking, when a little though and the sea could have stayed as it was a natural inland sea, and, power be generated further north of it. But unwise decisions were made that took little or no account of local ways of life and industry. In affect, a small Country has been obliterated, all because some megalomaniac (and I do not include you in this description in anyway shape or form!) decided to 'make their mark' in history and do things they could do because they were relatively far from any governing body and, they thought the are several hundred miles away was of no import. Or it just did not enter their minds? Who knows.

With respect to your ideas. I think you could get the power you would have generated with your water project, by other means. The sun is the most obvious . And there is already at least one site of a solar powered energy station in the US. How about geothermal? Or a kind of link to that which could involve extracting the heat from the sand. ................I do not know if this is your own idea, or you have been commissioned? And why. Is it to build a new town or City in the dessert?

This is rather long but, I feel I have to point this out. And forgive me if I may be teaching to the converted.

You say the immediate area will gain from a more water in the atmosphere. That atmospheric moisture will be extremely centralised......It will not create rain in the dessert. To do that some decent sized hills or a mountain would be needed. So the water from where ever, would have to keep flowing in to keep the oasis alive.

It would be interesting to hear the views of an esteemed Hydrologist on this plan or idea?

I think we will have to agree to disagree on whether other areas you may choose to extract the water from for your idea, will be damaged. I do not agree with your notion of using the 'wasted' river water which would flow to the sea anyway. That river where ever it it gathers water and areas along its length make use of it for food growth and industry. Take some of that water away and it is possible there will not be as much water............that is, not enough for the continued life and business to carry on as it did before the water was redirected. As I say an Hydrologists opinion on this would be interesting. I apologise BTW if you are an Hydrologist!

Take care and think and try to see a more complete, rounded view of your ideas. This included finding out what is likely to happen if there was likely to be a huge amount of salt in such a dry area. It may even affect the relative moisture in the air and, with lower moisture it could actually get even hotter I do not know but, all these things have to be thought about and, any details there may be in Libraries and or on-line brought together to see a more realisting plan.

Take care my friend. Sorry this is so long.

babybear, you're definitely a nice person, judging from both your tone and the contents...I mean the way you actually care for the local communities and stuff, and that's precisely what this world needs more of today.

...don't know if you realised it, but the last post contains a brilliant idea(yet amazingly simple!) which is widely used all over the world.

Solar heat collectors.

these collectors can heat water upto near boiling point, and all that's required is a little vacuum for this heated water to boil away, like in a typical marine fresh water generator.

drink or swim in the water and sell the salt!

or

(some guy patented this already, I think)

close-loop simple turbine cycle using freon(or something similar) as the thermodynamic medium(as opposed to air orspecialty gas in a normal turbine setup).

ok, let's get back to main course.....

instead of pits, a shallow valley-esque pit going all the way to the final operational depth might be a cheaper and more practicable solution.

imagine a shallow pit about 15 miles long and about a mile wide and 1000' at the deepest point.

that's about 1:80 gradient.... doable with everyday bulldozer and truck to ship the salt out.

with a few of these pan-type pits, de-salting work could go on at one while the others stay in operation.

to keep sandstorm at bay, I thought palm/date tree 'fencing' around the full perimeter of this facility might do the job, just like how it's done already, in those places.

looks like tapping fresh water for this project might get touchy, so I'll stick to sea water then.

this way, there's money in electricity, in salt and I get to give back to the local community(if there's one), in humidity...and lots of trees!

ok guys, small diversion, how about piping fresh water from Nile or Lake Victoria to folks who have no water supply....using the same technology?

I appreciate the 'alternative' proposals, i.e.: geothermal, solar array, etc, which I am aware of. I thought this particular approach a little 'wholesome', i.e.: the byproducts is useful in itself, and in more ways than one.

I hope introducing a conducive environment for community to survive where none existed before is a good thing!!!...but that wasn't my original intention.

the original plan is to produce electricity from existing hydraulic head that is naturally available, ......everything else just happened or more likely, might happen.

How do you guys think this idea fares compared to normal hydro-plant.... jungles/wildlife/communities get destroyed and here... we create new ones..!?

Hydro electric in the sahara? What? There's not enough sun? You might do well to consider the 300 mile trench to bury your power transmission lines and just use the plentiful sunlight that's already there that way you're not importing a problem and its associated pollution, maintenance headaches and so on from afar. ...........................A curious pile of atoms,animated and self aware, looks upon itself and wonders why it wonders.

This would be a very ambitious plan yet all in vein due to the already comented issues you'd have to face to make it a reality.

Interesting notion.

So we could get E, desalinization of H2O and NaCl (table salt) export revenue! A trifecta.

Seems to be a net loss every way you look at it. It would probably be better to pump the waste water onto the surface and reclaim the salt; but that uses the energy gained from the hydro generators. Capturing waste water in the second, very-deep-but-not-very-broad, pit would create a situation in which evaporation is restricted, and water (salt water) percolation downward is magnified; in exchange for electric power you would eventually lose already limited fresh water reserves...a problem already facing Saudi Arabia. Again - if Nigeria wants to go on drinking - the cost to replace lost fresh water would far exceed the benefit of the slant well hydroelectric system.

Or at least it seems that way from here.

300 to 500 miles away? could you create a vaccum with pumps so the water would siphon to the pit ?

Brining water to the desert is a great idea and I think it should be combined with the use of solid waste from sewer plants to create topsoil starting from the edge of the desert and push back against desertification.

hi dadw5kids, why do you need vacuum when the tapping point has a huge head?

you could, but you 'environment' has to be at level low enough(below river/lake level) for the water to flow/spray, and the spray height won't be higher than river/lake level, minus flow-resistance equivalent head loss.

Hello rmg21,

Are you ok?.......I have been reading the conversation between dadw5boys and you. It is interesting and it would be nice to think we had a part in your future success!.

In thinking about the water extraction point. And with ref' to pressures as you have been discussing, would it be any advantage to draw the water from a source directly North or South of the planned build?

My thinking is that the natural 'throw' of the spin of the earth would spin the water toward the equator. Giving you more pressure with no extra power? I do not know about this but it sounds like it would work like that? It would be so nice to hear from a Hydrologist. HELLO ANY HYDROLOGISTS AROUND?

I will be popng in to give my 'expert'........opinion...... I would like a few other Engineers to give their five penny worth really.

thanks for the positive outlook, babybear, ...appreciate that.

isn't the 'throw' already part of earth's gravity, i.e. 9.81xxx m/s/s ?

earth would need to spin faster(less gravitatinal pull) to add pressure for such flows!..and I don't see that happening anytime soon!!!

Hello rmg21,

I to hope the world does not start spinning any faster!

If I can take the time to explain my idea? The world is broadest at the equator. So my thoughts were, that if you could build your power station on the equator and draw water from north or south it should impel the water even more? Do you not think? Unless of course the distance was too near the equator and the force negligible? The other thing is that your pipe would have to face in the opposite direction to the spin to gain anything at all. Otherwise the water would be forced back down your pipe. Those are my crazy ideas anyway. They make sense at the time of writing, whether they will continue to (excuse the pun) 'hold water', remains to be seen.

Forgive any duplication. I was not well when I wrote my first post this morning, and actually do not doing do!

Depending on inflation I am sure what you put forward is going to happen. It simply all depends if and when it will pay/be worth the outlay at the time?

But, you still have some questions to fully answer. Not least what you will do with the salt?.............I do think taking the water from any other enclosed body will create problem there. And the oceans are large enough for a continuous 'trickle' not to be noticed. But, as I say, the outcome .....I THINK, would be disastrous if you tapped a river or lake. Even the mighty rivers of the world, like the Nile, Amazon etc have a finite flow. Though that may be a little OTT and extreme, as you will not be drawing that much water off.

Have you decided if you will have a man made lake to store the water to get the head needed? If so that area could also be the centre of Farming and food growth as, I would make a building of light plastic to prevent the evaporation. And at the same time it would mean a wonderful moist growing area, which you could import a few million tons of 'night soil' S-it....Ahemmm.......As suggested by the 'infamous' dadw5boys.!

Keep thinking and see if you can think of something to stop the salt, perhaps a desalination plant on the coast or a desalination ship? I think I will call it a day there as I am starting to make sense!

Take care and keep thinking!

Hi, bb,

If the Earth's rotation caused a pressure difference in a pipe of water from, say, the Arctic circle to the equator (starting and finishing at local sea level) resulting in flow, wouldn't the same happen to unconstrained water (as in the oceans)?

Hello JohnDG:

I thank you for your...........carefully worded phrase there.

Uummm, the same does happen with the oceans. Well it does when the gravitational pull of the moon gets working and creates tides? Is that not so John?

I did not mean to , and now I have forgotten the word!...............assert the action would be continuous.

Have you any knowledge of Oil pipes and their flow toward the equator? And if that surge when the moon is near would give a slight 'helping hand' to the pumps?

Thinking about it, I suppose most Oil lines go in the opposite direction.......away from the equator?

Take care John................

Yup, John G -- It's what keeps you folks in the UK warm in the winter. In the colonies we call it the Gulf Stream. Another clockwise ocean circulation in the Pacific gives the California coast its moderate climate. There are similar circulations south of the equator that rotate counterclockwise. Air flow around the earth behaves the same way (trade winds, westerly winds in temperate latitudes, etc.)

There have been actual "back of the envelope" ideas about using the approx 4 knot velocity of the Gulf Stream along parts of the US coast to generate electricity. Sort of like you'd anchor barges with propellers driving generators hooked up to undersea electric cables out in the Gulf stream off Florida. Then you'd have to figure out how to keep them from being torn loose by hurricanes. Haven't yet heard of any of this reaching a serious proposal stage, though.

Ed Weldon

Hello Ed,

I appreciate the confirmation of my theory. Makes me feel all warm inside when an Esteemed Colleague agrees with my way the world works, thank you Ed.

Ain't it nice when the notion

is correct about the motion?

Take care. Thought I was swimming against the tide literally there.

hi babybear, need your input on the unanswered questions....

..plan is to ship the salt out by truck(as explained earlier) and sell it!

we could built a giant pond/reservoir at ground level(that's gonna cost a lot of beer!) and dig a pit at a lower level to hold the drain water... and we can't afford to lose the water either, need to recycle that.And drain-evaporation-condensation(back to the reservoir) cycle would need a massive setup!!!, and cost even more.

desalination with a combination of desert heat-vacuum chamber combo. sounds good too---deal with the salt before it hits the turbines.

looks like we'd working on the project/business plan soon......

"we could built a giant pond/reservoir at ground level ..."

What for? Getting the water from your turbine hall to the surface would use all the energy you've generated - and more!

Hi JohnDG, that is true. Actually I was replying to babybear on his proposal.... a fully self contained system, of sort...............

Hello rmg21,

I have kinda lost the plot really, as you may have gathered?

Just a thought, and mention was given to some part like this by another, and I apologise for not recalling their name,.................Do you think it possible to narrow the pipe just before the generator, enough to give you power enough to drive the turbine, withing a closed loop. Have a pipe, if necessary loop up to or above the surface in an ovoid. (If that is the correct word).

Allow the water to flow through the impeller then, on out through a one way valve to another pipe, which will be continuously be supplied with the spent water. Less some water that the Town needs to function, as explained below This pipe would perhaps have to be virtually level and it will flow back to the ocean. Either whence the other pipe came, or perhaps to possibly a nearer coast?

All will be completely enclosed, no evaporation, no salt problems. Though you would loose currency on the lack of salt sales.

Or do exactly the same thing but have the original water taken from a desalination plant on the coast? That means you could have a spur from the main water supply to feed the Utilities of Business and Dwellings At least if you did that the turbine will have a longer life than with salt water?

Just a suggestion................................

Hi babybear,

That's perpetual motion stuff!... sorry buddy, but that's not gonna work.

first, portion of potential energy in the water would be lost as it flows thru' the pipeline from the coast/seabed to turbine inlet.

Next, bulk of the potential energy would be sucked out by the water turbine-alternator, and then the drain water pees out into the sand........

forget about the water flowing back up to the surface, you won't see that happen..... there would be no energy left in there anymore!

reducing pipe size at turbine inlet(or any other point) would convert potential energy of water to kinetic one.... water would flow faster, that's all. This would be done at turbine inlet anyway....... to meet the turbine blades at the right angle and speed.

Hello rmg21,

No probs with your remarks........Just throwing eggs at the wall to see which ones are hard boiled!

I am to the shops soon, so will catch you up with any updates to this later.

Hello John,

What for? Getting the water from your turbine hall to the surface would use all the energy you've generated - and more!

Look,.............Someone has to say some stupid stuff for the continuation of the post! Often the best parts are like dinner, at the end! As it happens I drew the short straw this time, OK?

You better watch yourself. I am on the Board of this project. A fully signed up w an hankies anonymous. I will have to stop swigging that wine vinegar!

Take care....................

Hello rmg21,

OK, so I am on the 'Board' now then?

I understand you are a busy man at the moment so, I would be obliged if your secretary could let me know when the next meeting is please?

I have an appointment in Saville Row with Gieves and Hawkes for a dozen 'Summer' suites, well, with matching shoes. One should always look presentable at the meetings, do you not think sir?

I have started using A3 envelopes now. I find there simply is not ample room on the C6, do you not find?

PresentlyI am doing roughs on the ROUTER; Reverse Ultra-Travel Energy Regenerators, I think this should prove sufficiently adequate to return 'spent' water to it's origin. Working on power saved through out the daylight hours, it will return the medium to the upper lake level, filtering detritus that may damage the impeller.

Forgive me, I must depart from this communication forthwith. I have pencils to sharpen for the continuation of my endeavours.

By for now old chap...........

Reginald Cumminglast Facquaharsen

Hello dadw5boys:

Hope you are well?..........Look, I have pretty much had my say, and do not want to 'rub' the OP up the wrong way. But, must comment on your comment......

You know a new Race way for F! was build in the dessert? Well, they find it difficult enough keeping the sand off the tarmac whilst the race is on which is about 2 hours.

People have tried and failed to hold back the sand. If you look at most big Cities there, they have a continuous fleet of earth moving equipment removing the encroaching sand away from the lived in areas. Even so the road are covered in sand as you get down wind of the dessert.

Whatever soil......I believe it is known as 'night soil', if you see what I mean, what ever soil you dump there will be buried after the first sand storm. There is reasons why this has not been done before. The Kings of all of those linked Arabian gulf Countries have money flowing like water (sorry for the pun, unintended) and even they have not succeeded to reach very far into the dessert. All habitat is close to the coast. Pretty much anyway.

Take care............