Hydro choices, location and turbine type

[Jedon]

So I'm trying to get my hydro setup all planned out and have some choices. There are two potential sites:
1. Spring - A spring starts on our property and flows downhill a total of about 400ft elevation over 2200ft and empties in site 2. Flow is 30gpm at the end of summer and 130gpm now in winter. Most convenient location for the turbine ( Pelton ) would be 600ft from the top of the spring so 600ft of 2-3" pipe for the penstock, and then it is 800ft to run wire to the batteries.
2. Creek - Bloody Run Creek runs through a corner of our property and is big, maybe 1000gpm or more. There is a 25ft waterfall so we could get probably 40ft of head with a 60ft penstock. The low head indicates this might not a be a good match for a pelton or turgo  but there does not seem to be an affordable off the shelf crossflow/Banki-Mitchell setup that I could find on the web. The site is also 2500ft from the batteries and it not easily accessible, no vehicles etc it's very steep.
So do I go for the higher power capacity site further from the house that has a nice short penstock but a really long wire run or choose the easier smaller closer site with less capacity?
the pic of the waterfall is from a few years ago in summer and that's not me in the pic. Spring creek pictures are from Sunday.

[mike90045]

My thoughts:

Spring water will have less rocks and twigs in it, but flow may fade before winter rains start.
A lot of 2" or 3" pipe to lay

Creek - do you think you have actual rights to dam and divert (even if only 5') into your penstock?    A whole lot of expensive copper or aluminum wire - i think I'd go with the pipe at the spring

[Jedon]

There is a little pool above the waterfall I thought I could put the intake there and just run the pipe along the hillside down to a good spot for a turbine, it's all on my property but I suppose the County or Tahoe National Forest may have something to say about it if they knew, but it's not visible or accessible so?
I need to go down to the waterfall and really check the site out again, I haven't been down there in quite a while.

[mobile_bob]

do you have a need for more power?

if you truely have a need for the extra power available from the more difficult site, then that
is the site i would do my damn well best to harvest.

sure there are issues of distance, but what is the return on investment?

it might be the extra money spent to tap the better resource will turn out to be the best investment
over time, and that time may not be very long at all.

there is an old saying amongst mechanics, when you set out to buy a toolbox, buy the biggest one you can
afford, otherwise you will spend three times as much and end up with the bigger box in the end anyway.

that assumes one is going to be a mechanic on cars, trucks or the like and not a watch repairman 

it really comes down to what your needs are, and whether you can use the extra power of the larger site.

bob g

[mbryner]

Beautiful place, Jedon!   Looks sort of like our creek, but the paved BLM road is next to ours, so it's hard to bootleg anything along it.   Either site you pick is a gold mine of power.

Personally, I would pick the spring.   Question: you mention you have 400 ft head over 2200 ft distance, but then you say you are thinking about running about 600 ft.  What is the vertical head over that 600 ft?   If you use whole 400 ft drop at 30 gpm, that's 400 x 30 / 10 = 1200 watts (assuming average efficiency).    Even with a battery bank and diverting load (i.e. hot water tank), that's a lot of power for a single family home.   A larger battery bank and 2nd inverter/more inverters is almost definitely cheaper than oversizing a hydro system, even if you do have huge loads occasionally.   If you use high-voltage transmission from turbine to house/system, 800 ft could be dealt with small wire, which is cheaper and easier than water pipe.

Does the spring flow at all toward your housesite?  And is it uphill from the house?   If so, and if the water was collected at the spring source, you could even divert water from the end of the penstock for domestic water use.   Hey, no well pumping!

Dealing with high flow is more difficult than dealing with high pressure.  And have you priced really large diameter PVC lately?   So the creek site is less desirable, I would think.

If you really need more power, then do what Bob G said.   Just my 2 cents...

Marcus

P.S. And I totally agree with mike90045.   Filtering the intake at a spring would be tremendously easier, and you could be in a lot of hot water if whoever found a wier/dam/diversion on the creek.

[Jedon]

Question: you mention you have 400 ft head over 2200 ft distance, but then you say you are thinking about running about 600 ft.  What is the vertical head over that 600 ft?

100ft

Does the spring flow at all toward your housesite?

No it all flows away from the house, downhill unfortunately.

Dealing with high flow is more difficult than dealing with high pressure.

That is indeed true and my search for affordable cross flow Mitchell/banki turbines was unsuccessful. I need to get enough head to use a pelton.

And have you priced really large diameter PVC lately?   So the creek site is less desirable, I would think.

I would wager that 60ft of large diameter PVC would be much cheaper than 600ft of 2"!

do you have a need for more power?

I would love to have more power and would find things to do with it, and it would make the wife happy.
Right now I'm the most concerned with getting something in, even if it's small, even a 100-200W would really help.
My plan is to start with the spring, first make a small dam and a weir into a PVC pipe with a shutoff, then start running pipe downhill and measuring PSI and flow until I have a decent amount of head for the distance involved. Then I'll buy the turbine and some appropriate wire and run it up to the power shed.

[lowspeedlife]

60 ft of pvc is pretty cheap, use the largest you can get, 4 to 6 inch at least. also use electrical conduit, it's a little more expensive but it's uv light resistant, normal plumbing pvc is not. with out the uv resistance it will become brittle & break, a 60 ft column of water 6'' in diameter has fair bit of weight i'd imagine.

Scott

[Jedon]

Well I made some more progress, I cut a path down to the spring and damned it up a bit and put in a 3" pipe. I'm getting 24GPM out of the pipe which still leaves enough water for the creek. Now I need a bunch more pipe and a pelton wheel / generator or alternator.
This looks interesting:
http://cgi.ebay.com/TRUE-PELTON-HYDRO-GENERATOR-1200w-PMA-KIT-ALL-NEW-/180528898067?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2a085c6013#ht_500wt_928
or
http://cgi.ebay.com/PELTON-TRUBINE-GENERATOR-2400w-PMAs-ALL-NEW-/310231277155?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item483b399e63#ht_500wt_928

Any comments about those setups? About half the price of a Harris setup.
I'm torn between dropping in a pre-made unit and scrounging one together.

[mike90045]

with increasing water pressure at the lower end of the pipe, you may need schedule 80 for the lowest sections.  I don't know if there is any heavy duty gray/electrical conduit.

[Jedon]

One good thing is that the pipe will not get much sun, the whole creek is under the forest canopy in deep shade ( as proven by the number of mosquito's! )
I'm going to try and run the pipe along the hillside parallel to the creek and then have most of the drop happen all at once at the end, should help with friction losses?

[Crofter]

Are you using the same diameter pipe all the way? I am not sure it is a good idea to do a quick drop at the lower end. It is only atmospheric pressure that is charging the pipe at feed end and it is possible to create vacumn cavitation if you get turbine freewheel condition. The resulting chugging with plus and minus pressures will play hell with your pipe anchoring and create pressure spikes. Usually there is a sharp reduction in size just before the turbine to make sure there is no cavitation in the pipe above, but I am only talking of relatively large bore you could walk through.

I have worked on lots of penstock installations from 4 ft diameter to over ten ft, all welded steel pipe, and was amazed at some of the elaborate transitions, anchors, vacumn breakers etc. but admittedly had nothing to do with the design theory. I dont know if there is basic info you could get your hands on, but it might save you wasted work and material.

[Jedon]

I hadn't decided if I needed different sized of pipes or not, I've even considered starting out with it only going half way down to get 50ft of head or so just to get it started. I was hoping to find some used or cheap piping, that would help determine what size to use. Is there a downside to using larger pipe besides cost? I'd like to keep it really simple so perhaps I should just run the pipe downhill parallel to the creek.

[d34]

water pressure is determined by the height difference from the entrance to the outlet and flow is determined by what size pipe it is and other restrictions... 2.31' of water equals 1psi... so for 50 ft of head (elevation difference, not length of pipe) u will have 21.6psi...

[Jedon]

Yes I realize I'll have less head and thus less pressure but I'll also be running half the amount of pipe and wire... I do want later to get more and more head, I have a total of almost 300ft of head I could get if I was willing to run enough pipe and wire but more than 600ft and I might as well go for the bigger creek.

[Crofter]

If you use a constant pipe diameter the velocity will be constant the whole length. Friction losses increase with  velocity and length so the dynamic usefull pressure at the turbine will be less than the static head pressure calculations so you must size your pipe to get the necessary flow, not from bottom head pressure but from something less than atmospheric pressure.  In other words it is easier to get your flow at the top with larger diameter pipe and it need not be rated for as high a pressure. Less chance too for the possibility of line pressure drop creating a vacuum. Plugging of the intake with junk or beavers has damaged systems. Make sure you incorporate a vent that cannot be plugged.

When the mines were operating here you used to be able to pick up thin wall steel pipe and victaulic clamps for scrap prices. All kinds of fittings and reducers are universal.  If you could find something like that used it might be cheaper than anything you could get new in adequate sized plastic.

What pipe size are you contemplating?