I’ve always enjoyed playing in streams and am fascinated by flowing water. Flowing water has power. And falling water has even more power. I have a spot that has a relatively small seasonal stream, but a tremendous elevation drop— 500 ft from summit to base.
Even just a few gallons of water falling this distance will generate meaningful power— enough to run a house! (or, at least, an energy efficient one).
My system started with the insulation of 1000 ft of PVC pipe. Which involved dragging 20 ft sections through the woods using a bungi cord harness and some good podcasts.
I then glued all the sections together and created a primitive inlet; once I validated my system head (initially 35, later upgraded to 55) I installed a electric motor and Pelton Wheel from www.HiPowerHydro.com.
The next step is getting the power somewhere. I had to transmit the juice about 3000 ft, so I choose to use what is considered “high voltage” DC about 100 V, which is produced by rectifying wild three phase AC at the hydro; this allowed me to minimize my wire usage; but over 3000 ft I still ended needing 6 gauge to minimize loss. (my design target was to realize at least 95% efficiency in the both my piping and my transmission wire, this is not the most economical choice, but was the most ascetically pleasing from an engineers point of view).
The spool weighed something like 400 or 500 lbs. Once I got it to the site I realized I didn’t have the appropriate equipment to unroll it. Since I was staring at the top of the hill I realized that my most efficient option might be to just roll it down the hill (I can be somewhat impatient).
I pointed it in the right direction, and let go.
This worked surpassingly well, though I did destroy a number of sweet saplings.
The wire also does not take the most direct path; but it was good enough for my application.
Once up and running my initial install produced between 50 and 400 watts of clean renewable power, at the high end it produces enough KWH/mo to run a mid-sized energy efficient home.
Hydro power is great, because its on “all the time” meaning you can greatly reduce the battery bank size for an off grid project. This also makes it very competitive with solar; running 150 watts continuously doesn’t sound like a lot, but it consistently outperforms a 1 KW solar array in the same area; and requires only a small battery system.
The stream I’m using has very high fluctuation of water flow depending on the monthly and even daily rain fall (from 3 to 100 gallons per minute!). To compensate for this, I decided to give the system the ability to actively respond to changing water conditions. (I thought this would reduce the time I spent hiking up and down the hill to turns valves on and off or switch nozzles, but in the end, I suspect it stayed the same, or even increased, because the ability for things to break increases geometrically with your system complexity). Fortunately, I like hiking.
The first think I did was I add some aquarium float sensors in the stream to determine the water level and turn a electrical ball valve at the bottom of the hill on or off.
This worked out okay, until the system was struck by lightening. It was also somewhat susceptible to debris and frogs.
I then moved to a very sensitive pressure sensor I found on ebay and used that to measure the height difference in the stream; but this turned out to be difficult as the resolution needed at the base of a 50 PSI system to detect a 1” or 2” of water level change is very high. Through the use of a custom op-amp I was able to accurately gauge these changes, but temperature fluctuations would through off my calibration leading to stupid system behavior (and more hiking).
Most recently I settled upon what I think is the most elegant solution— using the hydro motor itself as the sensor. The power output varies directly w/ water pressure which is a function of of stream height (which relates to flow rate in a constricted section). I’m able to measure the amperage on the electric motor output accurately enough such that I can predict when water flow is dropping or rising and open or close 1 or more valves.
The brains for this system is an ArduinoUNO; I use a european wall wart to convert 1 of the wild AC phases put out by the motor into 13.5 V DC, which powers the UNO and also trickle charges a DC battery.
I also use the UNO to switch valves on and off if the water flow rate is in between the various nozzle sizes available on the hydro. This enables me to capture 100% of the water flow at the highest efficiency possible. (different nozzle sizes have different efficiencies, so the one that is calibrated to your streams flow, may not be the most efficient).
Most recently I’ve added SMS capability to my project, so I can manually actuate the valves, increment the duty cycle, and also query the sensors.
This has proven to be very helpful, but is embarrassing when I accidentally text folks things like Valve 1 ON!
I’ve included the code for this project here. You are welcome to use or modify as you see fit; its good starter code for anything you might want to actuate remotely using your mobile phone. Please note, the original file is .ino rather than .txt.
This is called a “CrayFish Error”.
Later on I had a “Frog Error” which was very sad. Since then I’ve installed a much better screen on the inlet to protect curious frogs (though I suspect the first 4.5 minutes of the ride down the pipe must have been a lot of fun for the frog!)