Further reading:
Large Scale Hydro facts  All sorts of good info about large scale hydro.
Mini-hydro All sorts of info about small scale hydro. 

Last Updated June 2005

            If there is one thing that we have a lot of on this planet it is water.  In the ocean, on the land, even in the sky.  In fact there is about 326 million cubic miles (one cubic mile of water is more than a trillion gallons) of water on this planet.  All this water is constantly moving around.  about 280 cubic miles of the stuff evaporates into the air every day, and about 4 cubic miles of it fall on The United States each day.  It sloshes around in the ocean, flows underground in aquifers and runs over the land in the form of rivers and glaciers.  This stuff we call water has a couple of odd properties that are really great.  For one water is less dense when it is a solid than when it is a liquid.  It also can't compress in its liquid state.  This means that liquid water is among other things a wonder storage place for energy.  Being as it is very dense and also compressed as much as it can be.  Liquid water can hold much more energy than air because air can get all bunched up, water can not.  So when this water gets to moving around we have an excellent opportunity to capture some of this energy and use it.

LARGE SCALE HYDRO

            Not to long ago people thought it would be a great idea to build huge dams.  These dam's clogged up the rivers, disrupted lots of animals, homes, and made a general mess of the whole place.  But these huge dams did store up a lot of water so much water in fact that the Hoover Dam slightly changed the rotation of the earth, due to the huge amount of water that was relocated. When you force this water though a little hole in the dam you can use this very strong stream of water to turn a turbine and produce lots of electricity (about 20% of the worlds energy is produced this way).  There are some countries that get a majority of there power from large dams.  These dams produce 97% of the worlds renewable energy.  They don't pollute, don't create green house gases, and don't use foreign oil.  But the future for large dams does not look good.  Large dams always silt up.  No matter how hard we try, silt from rivers builds up behind the dams and eventually clogs up the dam.  Large dams also mess up the environment pretty badly.  Fish have a hard time getting over large dams, and all the river side habitat is now gone.  In short we probably shouldn't build any more large dams.

SMALL SCALE HYDRO    

            Many people live near a small creek or stream.  It is possible to use these small rivers or creeks to produce power without destroying the natural world around us.  All the good things about a large dam apply to small scale hydro as well.  If you have a stream in your back yard you can insert a simple structure that will capture a small amount of water and direct it to a small turbine.  These turbines can produce as much power as a small wind turbine.  And the nice part about a stream is they run 24/7.  Never again will you curse the cloudy days (if you use solar) or calm days (if you use wind).  In fact if you set up a hybrid system of solar, wind, and small scale hydro you should be able to power your house comfortably all the time.  Small scale hydro can also use existing structures so that more projects do not need to be created.  Falling water can also be used to power these small turbines.  Best of all these tiny turbines are well within the cost range for most people.  The future is bright for small scale hydro.