2. Micro - hydro
Technology
As explained above, the community based micro-hydro village electrification scheme makes use of a
water stream that flows through or near the village with a considerable flow of water and with a drop in
elevation. The theoretical available energy of a stream is proportionate to the drop (height difference)
and flow rate as given below. (This has been computed from laws of conservation of energy.)
By equating the potential energy at the top of the drop and the kinetic energy at the bottom of the drop,
the power that is generated ‘P’ can be expressed as;
Power (P) = gHQ (in Watts)
Where
= Density of water (1,000 kgm-3 )
g
= Gravitational force (9.81 ms-2)
Head (H)
= Drop (Height deference) (m)
Flow Rate (Q) = Water flow rate (m3s-1)
In the above expression, and g are constants. Only the Head and Flow Rate are variables.
Example:
If the Flow Rate and Head of a micro-hydro site are 0.03 m3/ sec and 60m respectively 1,000 X 9.81 X
60 X 0.03 = 17.658Watts Then the available power = 1,000 X 9.81 X 60 X 0.03 = 17.658 Watts
Although the potential of power is 17,658 Watts (17.658 kW), all this cannot be practically extracted.
This is due to various energy losses in the power conversion steps as explained in the next section.
10