Friday, November 25, 2011

Cold Weather Woes, Pelton Wheel 101

We had some cold weather last week which often raises hell with the intake for my generating system. This particular pelton-wheel requires 250-300 gallons per minute which is fed under pressure from a small intake pond located a ways up the mountain. The water line is 8" in diameter and aprox. 1900' in length with a verticle lift (rise) of 405' so it is pretty steep up to the intake pond which is located at the crest of a fall. That 'head' gives a pressure in the pipeline of 200 psi at the bottom which is plenty to spin the pelton wheel that in turn rotates the shaft connected to the generator. Totally green electricity to burn. I always say its free, but there is probably a direct cost of $150 per year in wear and tear. The only thing that generally puts out the lights is the intake screens clogging up in the pond above. Often in cold weather frazzle ice forms in the frigid stream. This slush clogs up the screened intake and starves the water line which looses its head height and you loose your electricity.

This means a trip up the mountain to the intake. In the old days it was a slug up that steep hillside, but several years ago, a logging road was built up the mountainside and crossed the creek not far from my intake. Only problem is that any time your intake needs attention, it is always either the darkest, wettest weather, or cold and deep snow, or both. Either way its generally a challenge to get there, or close enough to hoof it in the last section of switchbacks. I started up in my S10 pickup as it has a heater in it. The loggers always de-commission these logging roads in the winter with the occasional cross ditch, or water bar to divert running water. Theses ones just about swallowed my little pickup and fighting the snow on the steep grade I could see it was futile. So I went back and returned with my Honda quad which has never failed yet to claw its way up to the bridge where I scramble down the bank to the small pool..

First order of business is to break the ice on the pond and let it wash out over the lip and down the falls behind me. I get hold of the screen with a modified hoe and a little rocking and a little swearing it pops right off. This can get quite hairy in the really wet weather when the creek is flowing at a much faster rate.
There are some situations, such as a winter or fall rainstorm you can't even get close the the creek and just need to wait for the water to go down enough to see if the screen even survived.

 I replace the normal screen with a more open design that is more resistant to clogging with slush. I try not to have to put my arms in the frigid water but sometimes it is nessesary.

As a side note, it is not uncommon for cougar to come down off the road and cross the creek at the dam, which they leap in a single bound. I reckon they are sometimes wary and avoid using the bridge.
They probably do it all the time, but I only see the tracks when there is snow.
Any time there is deer tracks up there, cougar tracks will follow.

                                         Lynx tracks following the same trail.

Pelton wheel shack
I can adjust the amount of power I generate by means of an adjustable nozzle that directs the high pressure stream of water at the cupped pelton wheel. I try not generate any more than I need as a rule, any excess is just burnt off with an outside heater. Inside the house is a panel that shuffles the available electricity around on a priority basis. There are a series of  red leds that I monitor to tell me what I've got and where its going.
5000 watts of that free green power being put to good use!

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