Small scale pumped hydro electricity

[Monkey-D]

I looked into this years ago, there was a local guy that was an expert in these kind of projects, but Ive lost his details. but think it may have been Pat Downey below.

https://www.youtube.com/watch?v=r8mFwKi8KhY

and some reading;
https://www.crses.sun.ac.za/files/re...cj_lombard.pdf

I tracked down Adriaan Lombard that wrote that thesis in 2010. He is now working on large scale hydro power systems across the world.

He gave me some useful tips on how to calculate the viability of the system and what to do.
- I will probably only get to 3-5kw using the 63mm pipe with 90m head over 1.25km distance because of pipe friction. Could still be viable to top up the lithium batteries over a longer time period if needed.
- Going with a Pelton or other turbine wheel requires custom designing, pushing up the costs for small scale hydro. He suggested rather using a cetrifugal water pump running in reverse to get something off the shelf. His thesis includes how to select the correct sized pump after calculating your water flow rate.

His thesis is very technical, but I will try to make some sense of it. Thanks for sharing!

[RoelfleRoux]

Wow, when I predicted some education coming from this thread I was so right. Great thread. Thanks.

[JanB]

My gut feel is that batteries will be more economical than pumped hydro, but the latter will be waaay cooler, so please do that!
Subscribing.

[Monkey-D]

Most micro hydro systems use a running body of water as a constant source of energy to use and is different than PUMPED hydro where you use solar during the day (or another cheap energy source) to move the water where you want it to simply use as "battery" storage for charging your batteries later. Thus very little practical examples and research is out there for PUMPED HYDRO STORAGE to simply buy parts off the shelf.

I agree that this will be very cool and I believe it can be done cheaper than lithium when looking at bigger storage capacity. The bigger the capacity, the cheaper it will be per kWh. To add more capacity, you mostly add more water tanks/storage and MAYBE pumping speed and solar to get the storage full. Pipes (if done right from the start) and the labour to install, remains as is.

I'm a bit pushed for time to get everything powered by mid Feb, so the Hydro idea will be put on hold for now, but all planning will make provision for adding this later. I want to do this right and not rush into anything.

[Richard Mackay]

We have the 90m head because of the mountainous terrain and plenty of water. So I wondered about using this to save on overspeccing on the Lithium batteries and have 90-200kWh of spare energy storage on tap (literally) when we need more power.

Hydro power doesn't use water in proportion to the electrical demand. When the pelton wheel is spinning it will go flat out. (In fact if there isn't enough load it can take off and blow the electrical equipment due to over voltage)
So you need to use the hydro with a constant load. I understand that this will be when you're filling your tanks from the borehole (unless you also have tanks at the borehole?)
So the best option I reckon is to charge your batteries with the hydro power..

[mikeml]

....
- 20'000L of water storage capacity on the top of the farm (90m+ head) thus 9bar water pressure at ground level at the borehole.
- Solar borehole pump with 230m max head already in and working like a dream to get the water all the way up to the mountain (1.25km far and 90m head) though 63mm inside diameter Class10 pipe.....

It looks like you are considering LDPE piping by mentioning 63mm ID piping. the ID of LDPE is actually 65mm. Class 10 is not good enough for a 90m head, not enough safety factor. When you eg close a valve at the bottom without taking care to do it gradually, you will increase the pressure beyond 10b and the pipe will rupture. Also, to pump up the water, you have friction losses which you have to add to the 9bar static pressure.

With 63mm Cl16 HDPE piping, your headloss at 2800l/hr is 8.2m, so total head would be 98m. So CL16 should be fine at the "slow" flowrate of 2800l/hr.

How deep is your borehole? Remember to add this head to the 90m if you want the borehole pump to pump all the way to the top. I suspect that you might have to have a pump station at the top of the borehole, ie that the borehole pump has to pump into a tank there, and another pump to pump up to the header tanks. Your standard HDPE piping only goes up to Cl16

[JanB]

Most micro hydro systems use a running body of water as a constant source of energy to use and is different than PUMPED hydro where .....

Sure. The title of your thread is pumped hydro (i.e. storage), but the discussion itself is on generation.

[Monkey-D]

It looks like you are considering LDPE piping by mentioning 63mm ID piping. the ID of LDPE is actually 65mm. Class 10 is not good enough for a 90m head, not enough safety factor. When you eg close a valve at the bottom without taking care to do it gradually, you will increase the pressure beyond 10b and the pipe will rupture. Also, to pump up the water, you have friction losses which you have to add to the 9bar static pressure.

With 63mm Cl16 HDPE piping, your headloss at 2800l/hr is 8.2m, so total head would be 98m. So CL16 should be fine at the "slow" flowrate of 2800l/hr.

How deep is your borehole? Remember to add this head to the 90m if you want the borehole pump to pump all the way to the top. I suspect that you might have to have a pump station at the top of the borehole, ie that the borehole pump has to pump into a tank there, and another pump to pump up to the header tanks. Your standard HDPE piping only goes up to Cl16

Hi Mike. It's a bit off topic, but thanks for letting me know.

Borehole is 70m deep, but since static water level sits at 10m, we only dropped the pump down 35m using CL16 pipe (not cl10).

We do have a +-20 bar cylinder with bladder (not sure what you call it) on the ground, next to the borehole, to handle the hammer effect to avoid bursting pipes.

Pump is a submersible Nastek that can do up to 280m head (at slower flow rate ofcourse). So this could push water all they way up 35m+90m if we wanted to, although this is not how it currently works.

[mudgrubber]

Great ideas and comments and I think small scale hydro is totally under utilised in SA (last one I know of is on the Lesotho Highlands outlet near Bethlehem - a CDM project); small scale pumped hydro - whew not heard of it at all although I am out of the main stream having only ever looked at a few hydro projects used as aqueduct head loss options; stymied by government / municipality obfuscation, regulation and incompetence but very interesting (the feasibility was done by Oz consultants in a BEE type arrangement). My partner worked on Drakensberg, nearly got hooked into Ngula (he smelt the rot and retreated) and did feasibility work on the Tugela, Umgeni as well as Palmiet. As noted straight small hydro is still a little complex although with CDM a number of countries, China and India in particular have developed a heap of these schemes so there should be information and design details aplenty (maybe google UNFCCC CDM projects).

For the small semi private hydro schemes I do know of (Cathedral, Umzimkulu (re-built I believe), Polela and Volksrust), floods devastate them so allow for that. Eskom (now NERSA) have devastated a few as well with regulation bs.

So, you have a mountain - any option to build a dam in a catchment on the mountain and run straight hydro?

[cainslie]

Friend of mine's project, currently under construction.

He has year round water flow.

[RoelfleRoux]

Friend of mine's project, currently under construction.

He has year round water flow.

Tried and tested

[Wetkit]

Very interesting concept and idea's.

If you do go for hydro, what is the plan with the "used" water?

I always like the idea of going simple for remote operations.
Personally I would do a solar PV system for each building initially.
This will be the cheapest and quickest to start off with.
Select the correct inverter so that you can do future micro grid as mentioned and then combine that with the hydro.
At a later stage then start looking at combining the buildings power via overhead lines, but these do come at a cost as well.

What I do like is using your excess solar during the day for pumping water and then using the water during the night again for generation.
With a single central system, if something did go wrong, the complete site is down, but with a distributed system any part that fails will only affect that section and not the overall system.
Sometimes for remote locations that is way more important.

Let us know how you progressing and thanks for sharing.

[Monkey-D]

Friend of mine's project, currently under construction.

He has year round water flow.

I do not think that wheel is very efficient (according to all my research so far). But please report back when he's done.

[Monkey-D]

Very interesting concept and idea's.

If you do go for hydro, what is the plan with the "used" water?

I always like the idea of going simple for remote operations.
Personally I would do a solar PV system for each building initially.
This will be the cheapest and quickest to start off with.
Select the correct inverter so that you can do future micro grid as mentioned and then combine that with the hydro.
At a later stage then start looking at combining the buildings power via overhead lines, but these do come at a cost as well.

What I do like is using your excess solar during the day for pumping water and then using the water during the night again for generation.
With a single central system, if something did go wrong, the complete site is down, but with a distributed system any part that fails will only affect that section and not the overall system.
Sometimes for remote locations that is way more important.

Let us know how you progressing and thanks for sharing.

Water will be used for pumping to storage, drinking and greenhouse watering after use.

Everything you mentioned is the route we're going, yes:
1) Separate solar, lithium and inverter on each building
2) Transformers and mini grid between buildings to use combined storage and generation capacity at any building if needed.
3) Generator at single location to top up batteries of rest of grid or provide extra power if needed. Control still need to be figured out, but probably monitoring load and battery capacity at this building only should do.
4) Add pumped hydro to the mix and use less of the generator.

[JLK]

Haven't done these calcs for a long time but I think it as follows; 2800 l/u at 98 m is 2800 l/s x 9.81 m/s^2 x 98m /3600 s = 747 Watt, then less the friction in the pipe and efficiency of the generator.

Not sure the cost of such generator, but that not a lot of energy for a house.

[ekkekan]

A calc I found based on 2800L/h into a 60mm pipe at 90m head.

[JLK]

A calc I found based on 2800L/h into a 60mm pipe at 90m head.

According to franklin you only need a 1.3 kw pump (50% efficiency) to move the above, in reverse it can be more? Anyway I'll leaf it for the experts.