Hydroelectricity uses the energy of running water, without reducing its quantity, to produce electricity. Therefore, all hydroelectric developments, of small or large size, whether run of the river or of accumulated storage, fit the concept of renewable energy.

What are the advantages of your energy over electricity generated by a traditional power plant run by fossil fuels?

http://www.greenhome.com/blog/how-does-it-work-hydropower

http://water.usgs.gov/edu/hydroadvantages.html

http://www.treepower.org/biomass/quickfacts.html