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Siting for Nano-Hydro- A primer Bob-O Schultze KG6MM
ano-Hydro is the ability to generate 3 Amps or less of hydropower at least some of the year. An Namazing number of rural, and especially mountainous, homesites have this capability. Most anyone who has a couple of acres in the mountains somewhere has seen the phenomenon of little springs popping up everywhere after a couple of good rains or during snowmelt. True, most of them seem to pop up in the driveway somewhere or worse, in the cellar, but since most folks tend to build toward the base of the hill rather than the top, a lot of those seasonal creeks or springs can be harnessed to provide power during a time of year when the PV's aren't exactly boiling the batteries! The really fun thing is that as long as the water flows, you're producing power-24 hours a day and the sun doesn't have to shine at the time.
There are some nice advantages to a nano-hydro system. In most micro and larger hydro installations half of the cost of the system is the pipe. Usually, somewhere between 2" - 6" PVC is used in order to get enough water to the wheel without incurring horrendous pressure losses. Priced any 6"PVC pipe lately? Whew! With a nano system, 2" pipe would be the high side with most systems running 1-11/2" pipe. I've seen a fair number of set-ups get away with 3/4" and even one which used 1/2" poly but that guy was really into low-ball!
Another factor is the lack of a need for any kind of regulation in most systems. At ±3 Amps/hr, that's only a C/33 charge rate for a 100 A-hr battery and less than C/100 for a set of Trojan L-16's. Not much chance of warping the plates there!
Have you Hydro?
As with any hydro situation, what you get depends mostly on the pressure and volume of water you can deliver to the generator. Of the two, pressure-whether you call it Head, Fall, or PSI-is the bigger factor. Up to 100 PSI (225'Head) or so, the more you have the better you'll like it.
Exact measurements are not important unless you have very little or very much Head. As a rule, anything between 25' and 250' will work to some degree or another. Below 25' gets dicey unless you have a lot of water-say...20GPM or better, and even then the output may not be worth the investment. At 250' of head or better, you'll have hydro up the wazoo, but you may have to invest in heavier duty pipe to handle the pressure and unless you have lots of water, (in which case you should be thinking about a larger, possibly automotive alternator-based system) you'll need a very small nozzle to restrict the flow enough to keep your pipe full. A very small nozzle, in turn, means very good filtration at the intake to keep clogging down to a minimum. None of these things are insurmountable, just factors to consider before you buy your components.
Figure if you've got a drop that's clearly twice the height of your house or better, you're in the ballpark. If you need or want to know a more exact figure, I like the garden-hose method. You'll need two people (it's possible to do this with one, but frustrating and not nearly as much fun), a 25' length of hose, a tape measure, something to write with and on, and unless it's summertime, raingear and gumboots-kinky!
One person starts at the water source with one end of the hose and the other person goes down the hill with the other end and the tape
measure. Fill the hose (getting the air out) and have the downhill person elevate the hose just until the water stops flowing. Measure from the hose end straight down to the ground and record your finding. Make a mark on the ground so the uphill person can find it, both put their thumbs over the hose ends, walk down and measure another station. Note: you'll have to top off the hose a little each time to be accurate, so if you're not following a live streamcourse, the uphill party should have a jug of water along for this purpose. Continue down until you reach your proposed generator site, add 'em up, and there you are. Keeping track of the # of stations will also tell you how much pipe to buy.
Measuring G.P.M. (Gallons Per Minute)
Since we're not dealing with massive amounts of water here, the bucket method works as well as any with a lot less hassle. You'll need- a 4 or 5 gallon plastic bucket, materials to make a temporary dam at the source (plastic sheeting, a tarp, rocks, maybe a shovel), a piece of pipe large enough to handle all the flow of your spring or creek & long enough to get the bucket under, a couple of sticks and string to support the pipe, and a watch capable of measuring seconds. (If you've wondered when you'll ever get a chance to use the stopwatch feature on your digital, Eureka!)
Before you head up the hill, dump exactly 1 gallon of water into the bucket and mark the level. Dump another gallon in and mark the 2 gallon level, etc,etc, until the whole bucket is marked. Set your test up something like this:
4 Bucket Capacity 3
Seconds to fill X 60
So, now what?
OK, at this point you should have a handle on three things: Head , GPM , and length of pipe needed. Now, measure the distance from your hydrogenerator site to your batteries. Given these four factors, any reputable hydroplant dealer should be able to advise you on: 1) the kind of systems he has available suited to your site 2) the right diameter of pipe to buy, and 3) a close estimate of the amount of power you can generate.
Home Power #15 • February/March 1990
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