Micro Hydro Scheme

is it even possible to use the extra flow at 20m? No. You need to overcome 30m of head already coming down the pipe. That is, if I understand the question.

And, we don't do homework here. Good luck.

hi, thanks for your response, i appreciate your time. Yes sorry the question was worded poorly. Do you know any type of system available that can utilise the extra flow from the 20m lake using the same penstock other than pumping up to the forebay at 50m? i've surveyed the site and the lake at 20m it is fed from a different spring system than the lake at 50... It can supply roughly about 45/50 l/s of extra flow but obviously with 30m less head. The lake at 50m is only supplying 30 l/s so i was wondering if a penstock able to be fed from both levels exists, or even multiple levels?

cheers,

tony

You might be able to utilize some type of venturi to "suck" the water from the lower lake. Don't know.

I can't go much further without getting yelled at for helping you with your homework.

Good luck.

thank you for your thoughts. I was thinking along the same lines. i wonder also if the pipe could taper so the flow velocity from the 20m lake feed would equal that of the flow in the penstock where the two join? i wonder if it has been done before? i have emailed some manufacturers..........

thanks

tony

eductor

eductor.......... thank you. creates a high pressure jet within the penstock which will 'suck' the flow from the lower feed.

thanks again for your time!

maybe an A+ for my homework!!!

tony

If you pull really hard on your shoelaces, you can levitate, too.

could this not work?

Hi Tony,

Here is a link to a hydro site http://www.oregon.gov/ENERGY/RENEW/Hydro/Hydro_index.shtml

Determining Power

Once you have the flow and head figures, you can roughly estimate the potential power available, in kilowatts (kW), with the following formula: Gross Head x Flow x System Efficiency (in decimal equivalent) x C = Power (kW) C is a constant (the value is different in English and metric units). Examples:

1. 20 feet x 2 cfs x 0.55 x 0.085 = 1.9 kW or: 6 meters x 0.05 cms x 0.55 x 9.81 = 1.62 kW
2. 50 feet x 0.8 cfs x 0.55 x 0.085 = 1.9 kW or: 15 meters x 0.02 cms x 0.55 x 9.81 = 1.62 kW

thank you russ, great information. i get about 8.1kW from the 50m head and about 7.9kW from the 20m. i'm considering the costs of trying to obtain the extra power from the 20m head as cheaply as possible to make it worth doing or not.

If i want to use higher flows when they're available for the 50m option, how can i get that increased flow into the forebay and onto the Pelton wheel/turgo? More flow onto the turbine means a bigger nozzle area, which means either a spear valve (expensive) or an extra jet for times of high flow, although I don't know how to work it out. But what about the intake up at the pond? If you put a larger diameter pipe in, you're going to be sucking out maximum flow all the time, even when it's not being replenished by the stream, and if you put a small pipe in to get minimum flow, you can't get any more down it when there's more flow available. the wondering continues!!

tony

Sounds like great fun Tony - hope you keep us up on what you are doing - any progress.

Russ