Hydro Siting Part 2
Hydro Siting part 2
At most sites, what is called run of river is the best mode of operation. This means that power is produced at a constant rate according to the amount of water available. Usually the power is generated as electricity and stored in batteries and can be tied to an existing PV or other system. The power can take other forms: shaft power for a saw, pump, grinder, etc. Both head and flow are necessary to produce power.
The pipe then becomes a convenient measure of horizontal run if you use a standard length like 100 feet. If you are working with a brook longer than your length of pipe, then simply carry the pipe to the next section to measure and repeat the procedure as required, starting where you ended before.
It is probably best to «map» more of the brook than you intend to use. This will give you a good overall idea of your site and may reveal some surprises.
Measuring flow is a little more difficult. This should probably be done in more than one place too. This is because most streams pick up water as they go.
Therefore choosing the best spot for your system requires careful consideration of several things.
There are several ways to measure flow; here are two. In both cases, the brook water must all pass through either a pipe or a weir. The weir system uses an opening that the water flows through and measuring the depth of water gives the flow.
The first involves a technique very similar to the head measuring technique. You must divert all of the water into a short length of pipe.
This will usually require the use of a dam in order to pack dirt around the intake end. Pipe size may be from 1″ to 6″ depending on the flow rate. Once that is done the water is directed into a bucket or other container of known volume. The time required to fill it is then noted and this is converted into GPM.
The weir technique is more involved so if the pipe plan works—fine. This consists of setting a bulkhead in the stream with an opening cut in it. The water level is measured as it flows over and with the aid of charts the flow is determined.
Many materials can be used for the weir but sheet metal is the easiest to make since the thickness is slight. Wood requires a beveled edge for accuracy. A stake is driven into the stream bed a foot or so upstream of the weir and level with the bottom of the notch. This is the point the depth of water is measured since the level drops somewhat at the weir opening. Water flow should be measured several times during the year.
1 to 4 feet between depth ruler & weir Stake holding rulerWater height above Weir.
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