If you're one of those lucky people who have a source of flowing water on their property I really envy you. Micro hydro power is the most efficient way to generate electricity (on the order of 60% - 70% efficient). The other great thing about micro hydro is that it's a continuous power source. No wondering whether the wind is going to blow or the sun is going to shine.

Although larger hdro installations use turbines to generate electricity micro hydro mainly uses the trusted water wheel. Water flows either over top or underneath the wheel which turns the wheel which in turn spins a generator. The picture on the left depicts an undershot water wheel. The water flows under and is caught by 'buckets'.

An overshot water wheel on the other hand has the water drop into the buckets from above. This type of design is good for large diameter water wheels because the weight of the water in the buckets gives the wheel tremendous torque. The size of the wheel isn't what determines the amount of power that it can produce though.

The power that your micro hydro system can produce depends upon the amount of head as well as how fast the water is flowing.

The formula to calculate how much power your micro hydro system is:

Power = Head X Flow X Gravity

Head refers to how much the water drops before it hits your wheel. It is measured in meters and there are several different ways to measure it. The easiest way for a diy project is to use a garden hose and a pressure gauge. How to measure head will be discussed in another article.

Flow refers to how much water will be passing through the water wheel. Flow is measured in litres per second.

Gravity is a constant value and is equal to 9.81.

So, how do you know if micro hydro is right for you? Well, the first thing you need to do is figure out whether the government will let you put in a micro hydro system. They're very picky when you want to divert water flow, or slow it down etc. If the stream that runs through your property is fully contained within your property than you should be fine; however, if it enters or exits off of your property you'll have to go through the bureaucrats before you do anything.

The next step will be to take measurements of your stream. There are several different ways to do this; however, they're out of the scope of this article and will be discussed in another.

After getting approval and taking measurements you're going to want at least 500 watts of available power. Take note that this is the theoretical power that is available and you will not see this in the real world. Nothing is 100% efficient (although it would be nice). Whatever number you get from the formula you should multiply by 0.65 (65%) to get a rough real world value for the power you'll produce.

This number can be quite low. Micro hydro runs 24 hours per day so a system that produces 250 watts can generate 6Kw in one day!

If you have any questions or comments feel free to leave a comment or use the contact link at the top of the page.

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