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 :
Technologies Used :
- 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.
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.
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
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.
- 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.