Pumping water up a hill

Here is a challange for the engineers!

Two friends run a charity for disabled children in Tanzania 
and the hospital/accommodation is on top of a hill. Currently 
water is collected using a tractor and something resembling 
a water bowser (cart with barrel).

Down in a valley is the water supply, a well, about 3km 
distance and 500m below.

How can a regular (no matter how small) supply be arranged 
where:

1. fuel is very expensive
2. solar energy is almost unlimited in daylight hours
3. security from theft of the solar panels will be an issue 
   and possibly for the pump also
4. in the valley winds are light

Storage is easy since there are tanks for retaining water in 
the wet season. The supply of water becomes an issue in the 
dry season.

I considered Pulsometer pumps since they have no moving 
parts but require a steam supply, (I think). Also solar 
powered pumps at intervals if enough energy is available.

Any bright ideas?

Mike Joseph

Not sure if this is the best option but have you looked into 'ram pumps'. These use the water itself to perform the pumping action.

This **LINK** site is commercial but will give you an idea of what can be acheived.

It's quite a lift

A hydraulic system using a small plastic pipe?

A mining engineer would know

Use solar to create compressed air at the well

Use the air pressure to shove the water up the hill

Being that we commonly power our whole households with solar panels these days here in Australia, that would seem to be the obvious solution for a similarly sunny climate. Would power a small pump no problem. Security? Well whatever your friend puts in will face the same problem. Three kilometres of plastic pipe is likely to go walkabout too. They may have to hire an askari or two (guards).
Tis quite a lift at 500 metres. Depending on what types of pumps are available down there, it may have to be done in stages with small tanks along the way.

I used to use a bore pump that dropped down the hole and ran on compressed air from a compressor mounted topside. Just a piston going up and down forced by air on one side and pushing the water up the pipe on the other. Worked very well. No idea of the possible lift with it though. And compressor is more high maintenance than a simple electric pump unit, which is a big consideration in Africa.

There must be other water supply systems in use in Tanzania they can model from?

If fuel is expensive then can I suggest something like the diesel delivery technology used at my training centre just outside Alexandria in Egypt in the early 1980s.

Other suggestions involve taking the children to the water or taking the children's home to the water. (I mean the view is probably fantastic but 500m above the water supply?) Sink a bore from the children's home down to the aquifer? But it all comes back to cheap, secure, reliable? Choose any one (this being Africa).

Edited By Colin Whittaker on 23/10/2018 01:29:35

As Ady1 says it's quite a lift and would need pressures in excess of something in the order of 50 bar or 700 psi to lift water to this level. This would require secure fittings and some very high pressure plastic/pvc pipe.

Tables give the following pressures for 1/2 in plastic pipe:

a) Schedule 40; Min burst 1910 psi, Working 358 psi.

b) Schedule 80; Min burst 2720 psi, Working 509 psi.

This is at an ambient temp of 23C however the above ratings are REDUCED TO 20% of the above figure when the pipe is operated at 60C. An uncovered/exposed pipe running for 3km with a low flow rate could show a significant rise in temperature. The problem will be alleviated as the pipe rises and the head diminishes.

Martin

Edited By Martin W on 23/10/2018 01:37:33

Ever thought about windmills , they work in outback Australia , don't need a lot of wind to power them

and they work at night. They are a piston pump and do not require a lot of maintanance.

Ever thought about windmills , they work in outback Australia , don't need a lot of wind to power them

and they work at night. They are a piston pump and do not require a lot of maintanance.

Usually windmills are discharging straight into a tank or trough. I don't think they would have enough power to pump water up 500 meters at the pressures etc outlined above.

It may be the Africans have the best system in place already: vehicle towing a water tank that can be kept secure when not in use. It may be that bigger/more vehicles and tanks is the answer. Not cheap of course. Any scope for running tractors on biodiesel made from local crops at all?

An 8 foot windmill will lift 185 ft about 150 gallons per hour when using 13/4 pump .

look into sinking a new well, it may not be as deep as you think. My aunt lived on top of a hill, but her well was shallower than the one at the lower end of the village. Water tables are a peculiar thing.
BobH

Depends hugely on the geology, but a group our Scouts have worked with in Zambia have drilled more than 50 wells by hand, with the cost coming out about £5k including the India mkII Pump. They are mostly drilling through sand gravel and clay to a depth of 30 to 50 metres.

They use 2" black screwed pipe, with a home made drilling head (mostly weld and bits of hss) and a cheap non-return valve... which they suspend using a convenient tree or tripod....

They dig a small hole and fill it with water, then lift the "drill" up and drop it in the hole.... The head loosens the ground and the waste is carried upwards inside the screwed pipe and fountains out of the top. More pipe is screwed on the top and the hole gets deeper. It can need a lot of local labour to lift the drill pipe but that yields a benefit that everyone in the village helped and has some ownership of the project... at the end they pull the drill pipe up, push plastic pipe down the hole, and concrete the top over and mount the pump.... They add bleach to kill any contaminents pushed down during the "drilling process" and after a week start to pump the trick is to make sure the water comes from deep enough to be clean

It sounds (and looks) totally Heath Robinson, but it's done with local people, money raised here and in the US and makes a real difference. They've now dug/refurbished more than 50 wells and established a maintenance team for the next 10 years,,,, 60,000 people have clean,sustainable, water that they produce themselves

The charities Water Aid and drop4drop are very knowledgeable in this field.

A solar powered electric buggy with a water tank is probably the best modern system

Low maintenance and nothing to steal at night if it's secured on site

Anything is possible of course if you have the money and materials.

However, given the lift of 500m pumping pressures in excess of 50 bar are probably not feasible for your situation, so stage pumping would be required, as a minimum 5 stages with tanks and associated control gear. Even in the developed world, pressures above 15 bar for public water distribution systems are avoided if possible primarily on grounds of cost and safety (cost of fittings doubles if you have use NP16 or higher).

You haven't stated volumetric requirements, but assuming that you can maintain a flow of 10 ls, the power requirements even to lift 100m are quite significant HQg/e1000 would be approximated to 110 10 10/800 just shy of 15kW for each stage of pumping (because water is heavy - if you don't believe me fill a couple of 20 litre jerries and carry them up a 500m hill!).

so unless significant resources are available or there is a convenient perched aquifer on top of the hill a donkey cart is probably your best option

Lifting 1 Kg = 1 litre through 500m needs ~10m/s/s x 1 Kg x 500 m = 5000 joules = 5000 watt.seconds

So 1 litre/second needs 5 kW. Scale up or down to suit.

A good solar panel seems to generate ~300 watts in UK sun - more in Africa I guess. So you need about 18 of them to pump a litre a second (more actually allowing for efficiency) up 500 metres. Puts it in perspective.

Somebody mentioned hydraulic rams - these are OK if you have a decent head in the first place to run them, they can pump some of the water up to a considerably larger height. But if you had that the problem would be easier anyway. They are also very noisy!

.

Volumetric requirement was effectively stated by:

"How can a regular (no matter how small) supply be arranged ..."

but I doubt we can take that literally.

MichaelG.

One or two comments:

500 m is quite a high lift, but achievable with multi stage centrifugal pumps. The problem is the power demand will be quite high at even very small flows. Would need a lot of PV panels. You could perhaps do a lower flow with a positive displacement pump, but even then flow would be tiny or PV panels would be many.

Incidentally, power demand [watts] = density[1000 for water] x gravity [9.81] x head [metres] x flow [m3/s] / efficiency [fraction]

Compressed air - compressed air is notoriously inefficient at doing anything. It just wins on convenience, but in the OP's context where energy is an expensive commodity - forget it.

One way out project I got involved with used a pump running as a turbine (yes they can and do), which drove a positive displacement pump to pump a small quantity of water up a big hill. The driving water for the turbine was a fairly large quantity of non-potable water at relatively modest head. The clever bit is selecting the two pumps so it works. You also need a certain amount of control and safety gear.

Hydraulic rams, need a good supply of driving water and quite a lot of building work for the installation. A Blakes Hydram brochure (happened to be next to me) reckons they are good for up to 1000 ft, which would not be enough for the OP's target.

Maybe a hybrid system? Use a hydraulic ram to get so far up the hill, then a solar panel powered positive displacement unit to go the rest?

Martin

Is it off the wall to suggest powering the thing with a stirling engine heat side from solar reflectors and cool side with some of the water?

According to one of the old locals (here in rural wales) some folk used to get their water via a simple overhead cable with tiny buckets powered by the remote stream they got the water from. I can't remember what the syetem was called but reported to be quite efficient.

pgk

If people / wheelchairs / vehicles are presumably making the journey up and down the hill, perhaps you could use the descending traffic to pull loads up in the other direction or to operate a pump. As that energy is currently going to waste, it would come at little or no cost. Same principle used in a funicular railway but ideally much simpler / cruder.

Whatever you do won't be simple but the energy source is surely critical to it.

Murray