Micro-Hydro Electric Power Turbine
There are two basic kinds of turbines used in hydro systems:
Impulse turbines spin freely in the air. Water is directed toward the turbine by a spout or nozzle. As long as there is some flow, the nozzle can be adjusted to regulate the flow-especially in a cross-flow turbine. Impulse turbines are the most commonly used in micro hydro systems.
A reaction turbine is fully immersed in water and is entirely enclosed in housing, so that the full pressure of the water turns the turbine. These are more likely to be used if water flow is relatively consistent throughout the year and the water pressure (or head) is low grade.
Impulse turbines are more widely used, and these come in three basic kinds:
- the pelton is best used for a thin stream (low flow) of water falling from a reasonable height (high head). The blades on these are shaped like a double spoon that turns the water away from the angle of entry. The higher the head, the more effectively used is the pelton.
- a turgo is for intermediate water flow and fall (or head) conditions.
- a cross-flow is very adjustable, ideal for a variably flowing source of water.