Hydroelectric Power Generation: Components and Types

Hydroelectric Energy: How It Works

Hydroelectric energy is produced by the force of falling water. The capacity to produce this energy is dependent on both the available flow and the height from which the water falls. As water accumulates, it builds up potential energy, which is then converted into mechanical energy. This mechanical energy drives the turbine, and the generator subsequently produces electricity.

Dams: Structure and Function

A dam is constructed to create a reservoir, storing water during periods of high flow in the river. There are two main types of dams:

• Gravity Dams: These are made from concrete or masonry. They rely on the weight of their material to resist the force of the water. Gravity dams are suited to sites with either wide or narrow valleys but need to be built on sound rock.
• Arch Dams: These are made from concrete. They are curved in the shape of an arch, with the top of the arch pointing back into the water. Arch dams are designed to transfer some of the loads (forces) on them to the foundation (mountain walls) on which they are built. The strength of the foundation is used to help resist the loads, which could not be resisted simply by the weight of the dam wall alone.

Sluice Gate

A sluice gate is a mechanism used to control water flow, which is especially critical during a time of flooding.

Water Intake

These are the gates built on the inside of the dam. The water from the reservoir is released and controlled through these gates.

Penstock

The penstock is the long pipe that carries the water flowing from the reservoir towards the power generation unit.

Generator

The generator is where the electricity is produced. The shaft of the water turbine rotates in the generator, which produces alternating current in the coils of the generator.

Turbine Types

Kaplan Turbine

The blades of the Kaplan Turbine are not planar, as in other axial flow turbines. Instead, they are designed with a twist along their length so as to allow swirling flow at entry and axial flow at the exit.

Pelton Turbine

In a Pelton Turbine or Pelton Wheel, water jets impact the blades of the turbine, making the wheel rotate, producing torque and power.

Types of Hydropower Plants

Large Hydropower

Large hydropower facilities have a capacity of more than 10 megawatts.

Small Hydropower

Small hydropower facilities have a capacity of 0.1 to 10 megawatts.

Micro Hydropower

A micro hydropower plant has a capacity of up to 100 kilowatts (0.1 megawatts).

Types of Pumped Storage Hydropower

Pure Pumped Storage Hydropower Plants

These operate with two reservoirs: a lower and an upper one. Pumped storage power plants are operated on daily and weekly cycles and are designed to provide peak electricity during periods of high electricity demand. This can be done in a very short time, i.e., within minutes.

Mixed Pumped Storage Hydropower Plants

These are similar to pure pumped storage, but the upper reservoir also has a natural inflow, such as a riverbed.