Sharing penstock between hydro and domestic water supply

[dexterdixon]

Hi,
My house water supply comes from a stream. I am looking to upgrade it and put in a new intake higher up the hill to get more pressure. I would then ideally like to put in a microhydro scheme as the resource will be around 5L/s with 30m head.
The pipe that already runs all the way up to the higher spot is 63mm OD.

My question is - will it be possible to use the same penstock pipe to run a microhydro and also provide drinking (and bathing!) water to a property? I imagine installing a header tank (currently we have around 4000L @10m head) to provide a buffer for someone running a bath.

Any thoughts?

Many thanks

Tom

[bigrockcandymountain]

I don't see why you would need a header tank with that size pipe and that much flow.  Just t the line and enjoy.  I am extremely jealous of your resource. 

Maybe i am missing something.

[mab]

It should work fine - if you keep your header tank and it only draws water from the penstock when water is being used in the house, then other than a drop in power output when water is being drawn, the only issue I can see is that you may need to upgrade the strainer/filter system at the top of the penstock if it was only designed for house demand.

the powerspout calculator suggests you could get 406w with those numbers and your existing penstock (I guessed pipe id ~53mm), or about 660w if you upgrade the pipe to ~73mm id.

Like BRCM I'm wondering why you needed that big header tank (4000l is a hell of a bath) - unless the stream is seasonal? In which case it probably isn't worth the cost to upgrade the pipe.

[dexterdixon]

The current tank is only 10 meters above the house so would have to be bypassed when I take from 20m higher up. Currently the tank is filled from a culvert which is washing itself away. We have a silt trap before the big tank which has a sieve on the outfall. At this time of year (UK) we have to go up and clear debris (mainly twigs) from the sieve daily. For large chunks of the year it goes for months without a visit. There is a lot of sand in the area so somewhere for that to drop out would be good. The big tank also acts as a silt trap - although it's got no baffles it still accumulates a good cubic metre of sludge over a year. My plan is a sand bag and DPM weir feeding a coander screen intake. This then fills a large silt trap (which cab also act as a buffer) and connect it up to the pipe that runs up through the collapsing culvert. See how that runs for a bit filling the tank @10m - see how often it needs cleaning etc. Then join the pipes together and bypass the tank to give me loads of lovely pressure at the house (showering upstairs with only  0.8bar available is miserable!). Then look at the hydro once that's sorted. Just wondering whether there is anything fundamental stopping the two projects sharing the same penstock which, it sounds like, there isn't...

[mab]

Ah, OK, so the issue may be head available to the upstairs shower: if you shut off the Water to the hydro generator before using the shower then you should have ~2.8 bar at the upstairs shower. Fine.

But with the hydro gen running at max power (limited by the capacity of the 63mm penstock), pressure at the bottom of the penstock is only 2bar, and when you turn the shower on with the penstock already running at capacity (4.1L/s @ 2bar in my powerspout result) the pressure will drop further and you might find your shower is disappointing as well as losing output from the generator. It may still be OK as long as the shower flow rate is significantly less than the 4.1l/s the generator is using.

[bigrockcandymountain]

2 bar is about what our shower runs at.  It isn't a lot of pressure but works fine.  The shower should take 0.15 l/s approximately, so a very small amount of your total flow rate. 

What i wouldn't do for 406w continuously.  Cool setup you have.