They investigate water's potential-to-kinetic energy transformation in hands-on activities about falling water and waterwheels. During the activities, they take measurements, calculate averages and graph results. Students learn and discuss the advantages and disadvantages of renewable and non-renewable energy sources. They also learn about our nation's electric power grid and what it means for a residential home to be "off the grid.
Hydroelectric Power - an overview | ScienceDirect Topics
Students learn the history of the waterwheel and common uses for water turbines today. They explore kinetic energy by creating their own experimental waterwheel from a two-liter plastic bottle. They investigate the transformations of energy involved in turning the blades of a hydro-turbine into work This lesson provides students with an overview of the electric power industry in the United States.
Students also become familiar with the environmental impacts associated with a variety of energy sources. From where do we get the energy to cook our food, drive our cars, and turn on lights?
Think about this for a few minutes, and then I'll ask for your ideas. Write student answers on the board in two columns: one for renewable energy sources and one for non-renewable, but do not put headers on the columns yet. After students have exhausted their ideas, ask them what the entries in each column have in common.
Answer: One column is types of renewable energy, the other is types of non-renewable energy. Examples of non-renewable energies include: oil, gasoline, diesel, coal and natural gas. Examples of renewable energy include: wind power, solar power, solar thermal [for space and water heating], and hydroelectric. What are the benefits of renewable energy? Answer: Renewable energies do not significantly contribute to global warming and have an inexhaustible supply.
Where are hydroelectric power plants located? Answer: At points in rivers, at dams. Does anyone know how they work? Let's think it through. Has anyone stood underneath a waterfall? What does it feel like? Answer: The water pounds down on you with a lot of force. By the time that water reaches the ground, it has a lot of power. Does water falling from tall waterfalls have more or less power than the water from shorter waterfalls? Answer: More power. We can say that the water about to fall from a tall waterfall has more potential energy than the water at the top of a shorter waterfall.
When the water falls, or moves through the air, the potential energy decreases as the water gets closer to the ground. The moving water has kinetic energy , or the energy of movement. As the water falls through the air, its kinetic energy grows as its potential energy decreases. So when it finally strikes you at the bottom, all of its potential energy has been turned into kinetic energy.
This is in accordance with the idea that energy is never created or destroyed, it just changes form. That's the scientific and engineering way to understand why a waterfall has so much power. Have students solidify their understanding of the change of potential to kinetic energy with the Waterwheel Work: Energy Transformations and Rotational Rates activity by creating their own experimental waterwheels from two-liter plastic bottles. With this in mind, we can understand how a hydropower plant works. Imagine a dam on a river. A hydropower plant located at the dam takes the potential energy of water located high up in a reservoir and captures its energy as it drops to the bottom of the dam.
In other words, a hydroelectric power plant is designed to take that power of falling water and use it to create electricity. How is this done? The water in a reservoir behind a dam is very deep.
The water at the bottom of the reservoir feels the weight of all the water that is on top of it — which creates water pressure. The deeper you go in the water, the higher the pressure. Have you ever swam down deep in a swimming pool and felt your ears start to hurt? That is because of the pressure of the water on your eardrums! You are probably only swimming down about six feet in a swimming pool; imagine if you went down 50 or feet.
That is a lot of water pressure! The pressurized water is directed through large turbines shaped like fans, with blades that spin when the water hits them. When a turbine spins, it turns a shaft in the generator that generates electricity. You know how a house fan requires electricity to spin? These generators work in just the opposite way: when they spin, they create electricity. We'd need to do a unit on electricity and magnetism to understand how this works—but maybe some of you already know!
What makes hydropower an attractive energy source? Hydropower is an attractive energy source because it is renewable and clean. Renewable energy is commonly understood to come from the wind, sun and movement of water. Clean energy commonly refers to energy sources that do not significantly emit toxins and greenhouse gases.
- Syllabus for Hydroelectric Power - Technology and Systems - Uppsala University, Sweden!
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Renewable sources of energy are considered infinite in supply. Societal disturbance such as the s oil crisis and worse can be triggered by shortages in the production and distribution of non-renewable energies such as oil, coal and natural gas. Hydropower and other renewable energies are not as subject to these vulnerabilities because as long as we have the necessary technology, we can capture the renewable energy indefinitely. Clean energy sources include the renewable energies as well as nuclear energy. Burning sources of energy that are not considered "clean" releases harmful emissions into our environment.
These emissions pollute our land and water and contribute to global warming, which appears to have potentially catastrophic societal consequences. How does hydropower work? Hydropower plants harness water's energy and use simple mechanics to convert that energy into electricity. The basic components of a hydropower plant are a dam, water intake, turbine, generator, transformer, power lines and water outflow see Figure 1.
Figure 1. How a hydropower plant works. Most hydropower plants rely on a dam that holds back water, creating a large reservoir. Gates on the dam open, and gravity pulls the intake water through the penstock, a pipeline that leads to the turbine s. Water builds up pressure as it flows through this pipe.
The water strikes and turns the large blades of turbines that are attached by shafts to generators above see Figure 3. As the turbine blades turn, so do a series of magnets inside the generators. Giant magnets rotate past copper coils, producing alternating current AC. A transformer inside the powerhouse converts the AC to higher-voltage current that is carried on high-tension power lines.
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The "used" water is carried through pipelines, called tailraces, and re-enters the river downstream.