“Hydro-electricity is fundamentally the combination of water flow and vertical drop (commonly called “head”).
Vertical drop creates pressure, and the continuous flow of water in a hydro system gives us an ongoing source of pressurized liquid energy.
Pressurized, flowing water is a very dense resource, and hydro-electric systems convert a very large percentage of the available energy into electricity because the resource is captive in a pipe or flume.
People have been tapping the energy in flowing water for centuries, first for mechanical power, and, in the last hundred years, for electricity. Early applications included milling, pumping, and driving machinery.
Unlike wind and sun, the right hydro resource can be available 24 hours a day, 365 days a year. This allowed pioneers to run irrigation pumps and grain mills, and allows people today to make clean, renewable electricity at a reasonable cost…”