Introduction

Hydroelectric Energy is the energy derived from the power of water. When water moves (as in flowing river) or falls through height (as in water falls or fall after crossing a dam) it generates some forms of useful energy. Energy due to motion is Kinetic Energy while energy due to fall is Potential Energy. These energy sources are made use of in hydroelectric power plants to generate electricity for home and industry uses.

An hydroelectric power station may use a natural water drops such as water falls (as in Niagra fall - the picture above) or rapids. Where a suitable natural water fall/rapid is not available, a dam can be constructed (second picture).

How does Hydroelectric Power Work?

The water falling through the fall or the dam is channelled through the plant intake into a pipe (penstock). The construction of the penstock at most stations allows the water to go through a further fall before reaching the plant. This additional fall increases the water flow and pressure thus producing a greater driving force required to run the power plant.

The falling water flows into the turbine chamber where the power of the water’s pressure spins the turbine blades. This spinning turns the ROTOR (electromagnetic device) which is attached to the other end of the turbines shaft.

As the ROTOR spins against the STATOR - which consists of rolls of copper wires  (left picture) electricity is generated.

The electricity generated is conducted through the STATOR to a transformer which steps up the voltage and allow it to be transmitted to homes and industries for use.

Water storage reservoirs are available at heights for periods of low flow.

In short, the hydroelectric plant works similarly to Coal powered plants and Nuclear powered plants in the way they produce electricity.

Essentially, the three technologies produce the energy that drives the turbine and the electromagnetic rotor which creates flow of electrons (or electricity).

Is Hydroelectric Energy Renewable?

Yes, hydroelectric energy is renewable as there will always be continuous supply of water. Our World is made up of over 70% water. It is also a very clean energy that produce little or no pollution during the production of electricity.

Advantages:

• Where there are natural drops (water falls or rapids) cost of providing electricity through hydroelectricity is very low.
• If dam is constructed, it could be used as flood control measure or for farm irrigation.
• It is freely available, green and renewable
• It is clean and green. It does not produce emissions (e.g. greenhouse gases) that are harmful to the environment.
• It is probably the most widely used, particularly in developing and growing economies. It's proven to be more reliable than many energy sources.

Disadvantages

• Danger of flooding through dam overflowing.
• Damming could have some negative impact on the quality of water downstream of the dam.
• Re-channeling of water to get enough to drive the turbine could have effect on water available other purposes - e.g. fish habitat and drinking water.
• Where a natural water drop (water falls or rapids) are not available, building of the dam increases the cost of electricity production.
• Siting or finding a suitable location for the dam  could be very difficult.

Other sources of information:

• Ontario Power Generation