Max Corlett and Melik Terzian

What Is Hydroelectricity?

Hydroelectricity is a renewable form of clean power generation. People have been harvesting power of moving water for centuries. Originally, people used moving water to turn mills that performed many different tasks. Some tasks include grinding wheat, cutting lumber and powering textile mills. In the late 19th century, it was discovered that kinetic energy from moving water can be converted into electric power. The first hydroelectric generating station was built in 1879, located in Niagara Falls (3). Since then, hydroelectric power has evolved tremendously. Today, hydroelectricity is one of the cheapest and most efficient forms of power generation.

How Hydroelectricity Works

Most power generating stations use a technique called Storage Hydropower. This technique uses the kinetic energy from flowing water, and converts it into electrical energy. In order to obtain this energy, a generating station can be broken down into five main sections.

• Dam
• Reservoir
• Penstocks
• Turbines
• Generators

The first step to creating hydropower starts with a dam. A hydroelectric dam is a large structure that is made from different materials, such as rock, sand, concrete and steel. The dam is built in a location that allows the generating station to manipulate the flow of a river.

The second part of a hydroelectric generating station is the reservoir. The reservoir is created by the dam stopping the flow of water. Since the dam stops the flow of water, it allows the generating station to accumulate and store large amounts of water. The reservoir can be accessed and controlled by the generating station, as power is needed. The reservoir is built at a higher elevation compared to the rest of the generating station, so that when the reservoir is emptied, the water is able to gain kinetic energy through gravity. By creating kinetic energy, it creates enough force for the water to turn the turbines.

The next part of a hydroelectric system is the penstocks. A penstock is a large enclosed pipe constructed of steel. These are located between the reservoir and the turbines located inside the generating station. When water is released from the reservoir, it flows through the penstocks and is carried straight to the turbines. Just like the dam, the amount of water that can flow through the penstocks can be regulated by the generating station.

Once the water has flowed through the penstocks, it reaches the turbines. Turbines are located inside the generating station and are responsible for generating the electricity that we can use. When water is delivered through the penstocks, it flows at a high volume, carrying lots of energy. The water pushes against the blades on the turbine causing it to rotate. The other end of the turbine is attached to a generator.

The last part to creating power from water involves generators. Generators are used to convert the mechanical energy from the rotating turbine, into electrical energy. Generators work by using an electrical conductor in a magnetic field. By rotating a conductor through a magnetic field, it forces the electrons in the conductor to move. The electrons start to flow along the conductor, and this is measured as voltage (electrical pressure), and the actual electrons are measured as amps, which is the power we consume.

By using these components together, generating stations are able to harness power from the water, and convert it into electrical power that we can use. To learn more about this, follow these links

• https://water.usgs.gov/edu/hyhowworks.html
• http://www.wvic.com/content/how_hydropower_works.cfm
• https://www.youtube.com/watch?v=q8HmRLCgDAI

Where Is Hydropower Used?

Hydropower has become a major source of energy throughout the world. Many different countries rely on hydroelectricity as a source of power. Countries such as Canada, China, United States, Russia, Norway and Japan are all major producers. Today, hydroelectricity is responsible for providing around 20% of the world’s electricity (3). Generating stations are a popular form of energy production, and are located all over the world. These generating stations are responsible for producing billions of watts every year. Some of the largest generating stations are

• Three Gorges Dam (China)
• Itaipu Dam (Brazil/Paraguay)
• Robert-Bourassa (Canada)
• Hoover Dam (USA)
• Bratsk (Russia)
• Tarbela Dam (Pakistan)

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Advantages and Disadvantages

Hydroelectricity is a cheap and highly efficient method of producing energy. When compared to other forms of energy production such as fossil fuels, hydroelectricity is a clean and renewable source of energy. However, even though it is a clean source of power production, it still impacts the environment.

Advantages of Hydroelectricity

• Since hydropower relies on water, it is a natural and pollution free fuel
• Power plants have complete control of the amount of power being produced. Because of this, power plants to go from no power to maximum power instantly.
• Hydropower is a very reliable source of energy.
• Hydropower does not depend on resources from other locations. Because of this, generating stations can be self-reliant.
• The water cycle is a self-regulating system. This means the same water will be used over and over again.
• Water reservoirs can be used for other purposes such as irrigation, and recreational uses.

Disadvantages of Hydroelectricity

• Since hydroelectricity requires the damming of rivers, it can impact wildlife greatly. These dams cover large areas meaning that they can destroy habitats.
• Many fish such as salmon rely on swimming upstream in rivers to reproduce. However, hydro dams can prevent their migration patterns. This can have an impact on the fish population.
• Generating stations can decrease the oxygen levels in the water. This will also impact the species of plant and animals around the station (5).
• Hydro plants can change the temperature of the water, also affecting species living in the river (5).
• Construction of generating stations requires a large amount of land. Not only does this destroy wildlife habitats, but it can also displace humans from their homes. This can be seen with the construction of the Three Gorge Dam. More than 1.2 million people were displaced from their homes (4).
• The actual construction of the dams can release greenhouse gasses into the atmosphere.

Facts

• During the construction of the Three Gorges Dam, 13 cities, 140 towns and 1350 villages were flooded (4).
• Hydroelectricity is responsible for providing 63% of Canada’s electricity (2).
• Over 99% of Norway’s power is generated by Hydro (6).
• With Hydropower becoming a popular source of power generation, it is estimated to prevent the use of 22 billion gallons of oil and 120 million tons of coal a year (6).
• Hydro turbines are very efficient. They can convert around 90% of mechanical energy into electrical power (1).

References

1. Alternative Energy. (n.d.). Hydroelectric Power. Retrieved from http://www.altenergy.org/renewables/hydroelectric.html
2. Canadian Hydropower Association. (n.d.). FIVE THINGS YOU NEED TO KNOW ABOUT HYDROPOWER: CANADA’S NUMBER ONE ELECTRICITY SOURCE. Retrieved from https://canadahydro.ca/facts/
3. Hydropower. (2009, October 09). Retrieved from https://www.nationalgeographic.com/environment/global-warming/hydropower/
4. International Rivers. (n.d.). Three Gorges Dam. Retrieved from https://www.internationalrivers.org/campaigns/three-gorges-dam
5. Union of Concerned Scientists. (n.d.). How Hydroelectric Energy Works. Retrieved from https://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-hydroelectric-energy.html
6. Wisconsin Valley Improvement Company. (n.d.). Facts About Hydropower. Retrieved from http://www.wvic.com/content/facts_about_hydropower.cfm