The word hydro
comes from a Greek word meaning water. The energy from water has been harnessed
to produce electricity since long. It is the first renewable
energy source to be tapped essentially to produce electricity.
Hydro power currently suffices one fifth of the global electricity supply, also
improving the electrical system reliability and stability throughout the world.
It also substantially avoids the green
house gas emissions, thus complimenting the measures taken towards the climate
change issues.
Hydro projects below a specified capacity are known as small
hydro. The definition of small hydro differs from country to country, depending
on the resources available and the prevalent national perspective. The small
hydro atlas shows that the largest of the projects (30 MW) is in US and
Canada. Small hydro power has emerged as one of the least cost options of harnessing
green
energy amongst all the renewable energy technologies.
According to the power
generated, small hydro power is classified into small, mini/micro and pico hydro.
In India, it is being classified as follows.
Small hydro - 2 MW - 30 MW
Mini - 100 kW - 2 MW
Micro - 10 kW - 100 kW
Mico hydro - 1 kW - 10 kW
Projects with the range of 100 kW
and above feed power into the grid. They are commercial by nature. Projects
below 100 kW are mostly off grid options being harnessed for rural village electrification.
They come under the social sector.
Hydro Power
The basics
of power from water is the result of conversion of potential
energy (the water body at a certain height which is known as the "Head")
to kinetic
energy (a flow which is known as "Discharge" down the pipe) which is transferred
to the buckets in the turbine
(mechanical
energy). It is the prime mover for the generator (electrical
energy) which produces electricity.
Essentially power from a small hydro potential site is derived from two parameters,
head and discharge .
Where "head"
is the vertical height from which the potential energy of water is converted
into electricity after the fall and discharge
is the flow rate of the water in the stream/river.
Power (kW) = H * Q * Y
Where
H = Head in m(meter)
Q = Discharge in m3/sec (cumecs) Y = Specific weight of water, being the product
of mass and acceleration due to gravity (9.81 kN/m3).
An altimeter is used for head
measurement and various methods are used for discharge
measurement based on the site conditions. Limited civil
works is carried out for the development of the site for small hydro power.
To maintain the power quality controllers and electrical equipments is used.
