I built a small lake in front of my house several years ago, all this water rolling through has often made me wonder about harnessing it somehow. It is a fairly consistent flow all summer, quite a lot more in the spring time. I took this picture yesterday. The culvert is 18", the water is falling about 4 1/2 feet, using a 5 gallon bucket I shoved it under the flow 6-7 times and videoed it, so I could watch and count. It takes about 2 seconds to fill up the bucket, so figure 2.5 gal/sec is the flow. From what I have read on here it seems like a water wheel would be a good option here (Im surely no expert) but wanted to ask those of you who know more than I do what you think.
The spillway to the lake comes in from the top right corner of the picture (after a decent 1.5"- 2" + rain only, the recharge area is 600+ acres) and is perpendicular to the flow of the culverts. That presents the problem of having a LOT of water coming by, at times, within a 1' of the bottom of the culvert, of course then the culvert is flowing an entire 18" column of water.
My present idea is to build something of steel that hinges a wheel down into the path of the water, so that it can be raised to accomodate water flow when rains come. Picture the rear wheel and swingarm of a motorcycle, on a bigger scale. I would use a cheap 12V winch to raise and lower this wheel, so that the wheel's position could be adjusted as the seasonal water flow changes. Im thinking that even when the spillway is in flood stage and near the bottom of the culverts, I will still be able to keep the wheel in the flow as the spillway itself never gets up over the culverts. At that point it would resemble an undershot wheel, during summer the wheel would be lowered all the way down into the creek channel there, until it was flowing (nearly, without changing the direction of the wheel's rotation) "overshot" but not quite.
At present I am just beginning to get acquainted with hydropower. To date the only thing I have done with electricity generation is build a stationary bike that turns out up to 120v dc off of some motor I picked up at the scrap yard. It powers a sawzall or table saw or whatever pretty nicely with someone pedaling their butt off.
I have a boat dock about 50 yards from from the outflow, upon which I intend to build a completely grid free power system as a starter project. I have gathered some of the things I will need, I have a 2000W inverter, (4000w peak) a nice big trolling motor battery, and am working on finding a big old (not working) refrigerator to house everything electrical in that is on the dock to keep it out of the weather. Originally I was thinking I would use a couple of solar panels, but not really sure if they would be necessary considering the water flow never stops. Im going to have to buy a charge controller either way I guess.
Anyway, if this works well, I intend to redo my spillway in several years (when money becomes less of a problem) by way of channelizing with concrete. This will allow me to put a "groove" about 24" wide and 6" deep in the spillway bottom at the point where the water leaves the lake, and eliminate the culverts. This groove would run out nearly level all the way nearly to where the culverts empty at present, with the rest of the much wider part of the spillway dropping off at a much faster rate for the bigger flows. The walls which will support the water race will extend past the wheel site (wheel on backside of wall) preventing the heavy flow from damaging anything. I have a 8' steel wheel that I intend to modify by adding reinforcement and buckets- it is a natural gas pipe spool bought for 16.00 at the salvage yard- for this later project.
About the pics. FIrst is of the flow. Second is of the relation of the dock (red roof) to the pipe outlet. Third is the spillway coming in from the right, fourth is a continuation on to the right out of the frame in pic 3. Fifth is looking down the spillway, sixth is the dock.