:: Small Hydro Power - Technologies

Classification of SHP:

Hydropower may be the oldest but is still the most reliable source of energy with the bulk of its potential yet to be harnessed in many countries. In India, small hydropower (SHP) having the identified potential of order 10000 MW is considered a promising resource among the renewable energy sources.


SHP potential in Maharashtra:

The total potential of SHP in Maharashtra (up to 25 MW) is identified as around 600 MW, out of which 22 projects with a total capacity of 192 MW have been commissioned.

Lay out of SHP :

  • Run of river scheme: Power is generated by diverting the natural flow of the river to a water- conductor- system feeding to a powerhouse located away from the source.
  • Canal-based scheme: In this type, canal falls are used to generate power. This is small head and large discharge scheme.
  • Scheme on existing dam: The head created by an existing dam can be utilized to generate power. The powerhouse is located at the toe of dam.

Technologies Used :

Conventionally, impulse turbines are used for high head hydro projects and reaction turbines for medium and low head hydro projects. Recently, the turbines have been selected on the basis of specific speed which is the more correct approach.

Impulse Turbine :

Water impinges over the buckets mounted over the periphery of the wheel under atmospheric pressure. Potential energy is converted into kinetic energy. Common turbines in this category are Pelton, Turgo, Crossflow types. These turbines are characterized by high head and low specific speed.

SHP-Impulse Turbine

Reaction Turbine :

SHP-Reaction Turbine

In this type, both components of energy_Potential energy and Kinetic energy are present. The pressure inside the turbine continuously changes due to the designed water passage. The wheel is rotated due to the reaction force. Common turbines in this type are Francis and other axial flow type turbines. These turbines are characterized by medium to low head and high specific speed.

These days, small hydropower projects can be successfully set up by utilizing ultra low head as low as 3m by using modern reaction turbines like

  • Tubular turbine: Turbine is placed inside the tube which itself acts as water-carrying-passage. A bend is provided in the passage to take out the shaft. The generator is mounted above the tube.

    • Axial Flow

  • Bulb turbine: Generator is placed inside the water tight bulb which in turn is placed inside the water. Losses are minimised by providing an entirely straight water passage.
  • Straw flow turbine: In this type, the generator is mounted over the periphery of turbine.
  • Technologies used in case of existing facilities ( small dam / barrage/ weir ): Similarly, the SHP potential of the existing dams can be harnessed by using either the existing sluices at the dam or the Siphon intake, to carry the water over the top of the dam. The inflated weir ( rubber dam ) can be used to divert the water from a small stream.