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Hydroelectric Power Plant
DAM
Dams are structures built over rivers to stop the water flow and form a reservoir
The reservoir stores the water flowing down the river. This water is diverted to turbines in power stations.
SPILLWAY
A spillway as the name suggests could be called as a way for spilling of water from dams. It is used to provide for the release of flood water from a dam.
It is used to prevent over toping of the dams which could result in damage or failure of dams
PENSTOCK AND TUNNEL
Penstocks are pipes which carry water from the reservoir to the turbines inside power station. They are usually made of steel and are equipped with gate systems. Water under high pressure flows through the penstock.
A tunnel serves the same purpose as a penstock. It is used when an obstruction is present between the dam and power station such as a mountain.
SURGE TANK
Surge tanks are tanks connected to the water conductor system. It serves the purpose of reducing water hammering in pipes which can cause damage to pipes.
The sudden surges of water in penstock is taken by the surge tank, and when the water requirements increase, it supplies the collected water thereby regulating water flow and pressure inside the penstock.
POWER STATION
Power station contains a turbine coupled to a generator. The water brought to the power station rotates the vanes of the turbine producing torque and rotation of turbine shaft. This rotational torque is transferred to the generator and is converted into electricity.
The used water is released through the tail race. The difference between head race and tail race is called gross head and by subtracting the frictional losses we get the net head
ADVANTAGES
 Elimination of the cost of fuel.
 Longer economic lives than fuel-fired generation
 Operating labor cost is also usually low
 No green house gas (CO 2 ) emission during power generation
DISADVANTAGES
This projects can be disruptive to surrounding aquatic ecosystems both upstream and downstream of the plant site
It needs to relocate the people living where the reservoirs are planned
Dams may be subject to enemy bombardment during wartime, sabotage and terrorism.
Changes in the amount of river flow will correlate with the amount of energy produced by a dam.