Hydropower is a product of the water cycle. The water cycle means the cycling of the water on the planet. This cycle has four main stages; evaporation, condensation, precipitation and collection, which preserve the earth’s water without letting it, waste.
Evaporation is when water is transformed to gas by the sun. Condensation occurs during the process of this gas rising into earth’s atmosphere and becomes clouds and fog.
Precipitation is the process of rain, hail, snow or sleet coming back to earth, from the clouds. It either hits the ground, in which case it moves to the next level (collection) or it falls on plants which lead to the process of “canopy interception”.
In the collection process this rain, hail, snow or sleet either falls back to streams and other bodies of water (channel runoff) or to the land (surface runoff).
Hydro energy is the energy that is produced from moving water and is the oldest form of energy known to man. A hydropower plant converts about 90% of water’s moving energy into electricity contributing to maximum energy efficiency.
The ancient Egyptians and Mesopotamians first used hydropower for agriculture purposes nearly 5000 years ago. In the 5th century BC the Greeks used hydropower mainly for agricultural purposes, but are documented to be the inventors of water clocks, the oldest time measuring devices in the world.
In the 4th century AD water mills were found in Europe and Asia. In 1770, an American, Oliver Evans designed the first mechanical watermill and led to the watermill being incorporated into agricultural and industrial purposes through the 19th century.
In 1829, a French engineer improved the waterwheel to enhance its efficiency. Hydro-electrical power generation in the USA began only in 1880s and the world’s first hydropower plant was built in 1882 in Wisconsin. Today, the largest hydroelectricity power plant is the Three Gorges Dam in China.
Hydroelectricity is a clean, economical and renewable source of energy.
Dams are created to harness hydropower, and are built on reservoirs, rivers, and lakes. Dams have sluice gates, which control the flow of water flowing through the dam by opening or closing, which minimise damage to the plant.
During extreme rainy season, the power generated from hydropower plants is at their greatest, because the water is flowing more rapidly than normal.
A standard hydropower plant has a section that produces electricity (electric plant), a dam that controls water flow and a reservoir that contains the water used for electricity production.
When the gates are open, the water flows from the reservoir through the gates and spins the blades of a turbine. This turning turbine is connected to a generator that produces electricity.
During this process, the amount of electricity that is generated is directly proportionate to the intensity of the water flow, the extent of the drop and the amount of water that flows through the turbines.
The electricity that is produces is then carried across electric lines to supply power to areas both close to the plant and further away.
There are three types of hydropower plants. The ‘impound facility’ is a huge system which has a dam and a reservoir. The water in this system serves two purposes. It either meets the changing electricity needs to the area being supplied, or it maintains a constant water level in the reservoir.
A ‘diversion’ is when part of the river water is channelled through a penstock or canal. This type of facility does not need a dam like the impound facility does.
The ‘pumped storage’ facility meets needs when the demand for electricity is low. It pumps water from a lower reservoir to an upper one. When electricity demands increase, the upper reservoir releases the water back to the lower reservoir.
Hydropower plants have a range of sizes depending on a supply capacity. Large hydropower facilities are ones that provide electricity for entire towns and large factories with a capacity more than 30 megawatts.
According to the Department of Energy, small hydropower plants are those with a capacity of 0.1 to 30 megawatts while micro power plants have a maximum capacity of about 0.1 megawatts.
While many renewable energy sources are used to produce electricity, hydropower is the cheapest. This is because the initial cost of installing equipment, building a dam and filling it with water is only a one-time process. The water that is in the reservoir is free.
Hydropower as an energy source does not create pollution because there are no fuels burned during the process, no direct waste, and low output of carbon dioxide (greenhouse gas) compared to fossil fuel plants.
The major disadvantage of a hydro-electrical plant is its inability to produce electricity during drought season.
The pollution that is caused is because of the construction of dams and other mechanisms that are used to generate hydropower is also a disadvantage, while they can also permanently alter marine and wild life as well as the ecosystem.
There is also a high risk of failure if dams have not been constructed according to proper industrial standards.
When constructing a hydropower plant, there is often relocation of the local tribe or community living in the region, which is another major disadvantage.
Although the initial cost of building a hydropower plant may be high, later maintenance costs are relatively low, and they are solid structures able to withstand almost anything.
While producing electricity is its main purpose, it is also an excellent flood and drought controller.
New hydropower projects and improvements on existing ones will create many job opportunities in the future.