To know the power potential of water in a river it is necessary to know the flow in the river and the available head.
The flow of the river is the amount of water (in m3 or litres) which passes in a certain amount of time a cross section of the river. Flows are normally given in cubic meters per second (m3/s) or in litres per second (l/s).
Head is the vertical difference in level (in meters) the water falls down.
Components of a typical high head hydro installation.
(click for enlargement)
If P is measured in Watts, Q in m3/s and H in meters, the gross power of the flow of water is:
|Large||all installations with an installed capacity of more than 1000 kW (according to some definitions more than 10,000 kW)|
|Small||general term for installations smaller than 1000 kW (or < 10,000 kW). Also used for installations in the range between 500 and 1000 kW.|
|Mini||capacity between 100 and 500 kW|
|Micro||hydropower installations with a power output less than 100 kW (or less then 1000 kW)|