These are High, Medium and Low head sites. Your site's uniqueness means that you may be unsure of its true potential to generate electricity. HydroNI can undertake a feasibility study for you. The potential energy generation is a combination of water flow in litres per second and the vertical distance (head) that it falls.
High Head Sites
High head sites have a head (the vertical distance the water falls) of over 100m. They generally have little water, but still have a huge potential to be a succssful site. Characteristics of these sites are a large number of waterfalls or falls in the riverbed; usually fast flowing water; and they will be largely in the upper course of the river.
This type of site typically requires a Pelton turbine.
Medium Head Sites
This type of site has a head of between 30 and 100m. They will have a medium amount of water flow. Common characteristics are that the river is starting to meander (go around bends) and a small number of waterfalls.
This type of site typically requires a Cross Flow turbine.
Low Head Sites
Low head sites have a head of under 30m, however it is important to remember that unless a site has a head of over 1m it will rarely be viable. They will have large amounts of water. Very often low head sites will have little distance between the intake and the turbine, therefore there are usually at, but not limited to weirs. Common characteristics are deep water, the land along the river is prone to flooding and areas where the river is calm.
This type of site typically requires an Archimedes Screw Turbine or a Kaplan Turbine.
Please click here for an independent comparison of Archimedes Screw Turbines v Kaplan Turbines
Screw Turbine with Safety Screen