Which of the following determines the power capacity of a hydropower plant?
A. Length of penstock pipe B. Flow rate C. Size of reservoir D. Head E. Length from intake to forebay
Choose the most appropriate answer from the options given below:

Correct option is B

The power capacity of a hydropower plant is determined by:
1. Flow Rate (B):
· The flow rate refers to the volume of water flowing through the turbine per unit time.
· Power output is directly proportional to the flow rate of water
P ∝ Q
Where Q is the flow rate.
2. Head (D):
· The head is the vertical height through which the water falls.
· The greater the head, the more potential energy the water has, which is converted into mechanical energy by the turbine.
· Power is also directly proportional to the head:
P∝H where H is the head height.
Factors like the length of penstock (A), size of reservoir (C), and length from intake to forebay (E) may influence the design and operation of the plant but do not directly determine its power capacity.
Additional Knowledge: 1. Flow Rate (B):
· Measured in cubic meters per second (m3/s), it determines how much water is available for energy conversion.
· Higher flow rates lead to more energy production if other factors remain constant.
2. Head (D):
· Measured in meters (m), it indicates the gravitational potential energy available for conversion into electricity.
3. Penstock (A):
· A penstock carries water to the turbine, and its length/diameter affects water flow and losses but not the power capacity directly.
4. Reservoir Size (C):
· Reservoirs help store water for consistent power generation but don’t directly determine capacity.
5. Hydropower Formula Application:
· Hydropower plants maximize output by optimizing head and flow rate with minimal losses.