Small Scale Hydro Power
If you are fortunate to have a stream or river on your property, there are a few ways you can use water to generate electricity or pump water. Hydro power has the advantage that the supply is continuos as long as the stream or river doesn't dry up. In most cases, hydro power is more economical than solar or wind power.
Before doing anything you'll need to check your site for two very important factors: the amount of vertical drop of the stream (measured in feet) and the amount of flow of the stream. (Measured in GPM - Gallons per Minute.) You should also check with the local DNR (Department of Natural Resources) to determine what is permissible or not permissible with the source of water that you have on your land.
Editors Note: I'm not too keen on invasive type systems that dam or divert large quantities of water. One of the main reasons for using renewable energy is to avoid using products that can potentially harm our environment. So while you are considering using hydro power, I hope you will design a system that will not alter nor harm the ecosystem around you.
to measure the vertical drop
The best way to measure the amount of fall along the stream is to use a transit or laser level. You will want to measure the amount of drop from the highest point of the stream to the lowest point that you can effectively install a pipe to divert the flow.
You can also use a water level. A water level is nothing more than a long piece of clear plastic hose with water poured into it. The water in the tube will show the level of the water on the other end of the tube. This will require you to repeat the steps as you move down stream, but you can get a fairly accurate reading if you take your time with it.
to measure the flow
To get the GPM, the easiest way is to use a 5 gallon bucket and time how long it takes to fill up the bucket. Another method is to measure the length and width of the stream bed for a given area and time how long it takes a floating object to traverse from point A to point B. (There's a formula for this that can be found in Keith Ritter's book: The Residential Hydro Power Book. If you are seriously considering a small hyrdo system, I suggest getting his book for all of the details.)
Generators - Pelton Wheel
The most popular type of residential hydrogenerator is a pelton wheel turbine. Pelton wheels work best for high-head, low flow sites. The water that is channeled through a pipe is focussed on a series of cups that spin a wheel. The wheel in turn is connected to a turbine that generates electricity. Pelton wheels cost anywhere from $750 to $1,400 and can generate from .25 KWh per day to as high as 36 KWh per day.
Generators - Submersible Propeller
The submersible propeller works best for fast running streams. A stream that flows between 6 mph and 9 mph are adequate. They can also operate in as little as 1 foot of water. Typically, a generator of this kind costs around $1,200 and can produce between 1.5 KWh and 2.4 KWh per day. A major advantage of a propeller system is the fact that it doesn't require any modifications to the stream (a dam) to generate electricity.
about pumping water using the force of water?
Ram pumps have been around for a long time and are quite interesting to say the least. Ram pumps can be used for irrigation, gardening and bringing water up to a storage tank. Ram pumps are commercially available or you can even build one yourself.
does a ram pump work?
Water accelerates through a pipe and open waste valve. It's velocity increases until the flow and upward force causes the waste valve to slam shut. When the valve slams shut it momentarily produces a short-lived pressure that causes a small amount of water to be released through the check valve into the pressure tank. At this point, the pressure below the check valve is lower than the pressure in the tank and the check valve releases and the water is pumped out. This cycle repeats continuously as long as there is water flow. Although a ram pump doesn't deliver a large volume of water, it's continuous and even the largest of storage tanks will fill up with water over time. A drop of 20 feet will push 130 gallons up 150 feet per day!
I've heard of a story in which a couple were walking through the woods and heard a clanging noise. Upon inspection, they came across a ram pump that was built during the gold rush that was still working! I'm not sure if that story can be validated, but ram pumps do last a long time and as long as you have a decent amount of head and flow, it might be worth building one or buying a commercial unit