All energy produced by falling water is considered hydro-power. Small-scale hydro projects have low-impact by using only a portion of running water and returning it back to the water cycle.
Micro-hydro technology is an appropriate, environmentally benign energy system that can produce electricity at low cost to isolated communities wherever there are mountains and streams. The two key components of any hydro system are head (vertical drop of the water from its intake to where it turns the turbine) and flow (the volume of water available to turn the turbine).
A simple micro-hydro system is shown below.
B. Power canal/conduit
F. Electrical Transmission Line
G. Transformer House
How Does it Work?
A small wall of loose boulders or concrete diverts water flow from a portion of the stream to a submerged pipe whose size is determined by power needs and cost limitations. This pipe, labeled the penstock, runs straight down a steep slope along the ground sometimes for hundreds of meters until it reaches the powerhouse--the site of the turbine generator. The long fall of water through the pipe causes a small, high-speed stream of water to exit the pipe. This water stream strikes the small turbine causing it to turn at a very high speed. As the turbine rotates, a generator on the same shaft also rotates converting mechanical energy into electrical energy. The water is then castoff into a collection ditch (tailrace) that returns the water to the stream.