Hydroelectric Power
From wiki.NGSciEd.org
Lindsey P. Melea Q. Tara B. ISCI 2001
Contents |
Using water to generate electricity
Hydroelectric Power is power produced through the gravitational force of falling or flowing water. Most hydroelectric power is from the potential energy of dammed water driving a water turbine and generator. The energy extracted from the water depends on the volume and the difference in height between the source and water's outflow (2009, Hydroelectric Power).
The diagram below shows the process of creating hydroelectric power. At the higher water level, water flows from the reservoir into the intake and then through a pipe called the penstock. The water pressure increases as the penstock carries it down to a turbine water wheel at the lower water level. The pressure and flow drives the turbine that is connected to the generator. There is a rotor inside the generator that is spun by the turbine. There are large electromagnets inside the rotor, and as the generator rotor spins the magnets, a flow of electrons is created. Electricity is the produced through the station's transformers and sent across transmission lines. The water flowing through exits the generating station empties into the river to continue the cycle.
Positive benefits of Hydroelectric Power
Hydroelectric power has many benefits. Among the many advantages of hydroelectric power, we can mention that it has a very low cost because water is free. There is no cost to replenish the water since it is a renewable resource. It is also one of the most efficient ways to generate energy. Also, there is no pollution that comes with this type of energy. Hydroelectric power is reliable and has many natural benefits that come with it such as support fisheries from dammed up rivers. The benefits could go on and on about this type of energy. It is a great resource that we have and we should take advantage of the fact that it is a renewable resource, meaning it is a natural source of energy. Hydroelectric Power is the most widely used form of renewable energy, because of it creating no direct waste and its considerably different output level of CO2 than fossil fuel powered energy plants (2009, Hydroelectric Power).
Negative Aspects of Hydroelectric Power
There are some negative aspects of hydroelectric energy. The main problem that occurs with this type of energy is when rivers are dammed. Dams and reservoirs can harm downstream aquatic communities through loss of nutrients, primary productivity, and reduced stream flow. Another negative aspect is the impact that damming the water would have on the water quality. Effects are often experienced both upstream and downstream of a dam. Some of the effects can be increased or decreased dissolved oxygen, increases in total dissolved gases, modified nutrient levels, thermal modification and heavy metal levels. Cost could possibly be higher in the beginning to get the power plants operating, but the main negative aspects that come from hydroelectric power is natural problems in the environment (2009, Hydroelectric Power).
Hydroelectric Power in the United States and the World
Of the renewable energy sources, that generate electricity, hydro power is the most often used. It accounted for 10% of total U.S. electricity generation and 71% of generation from renewables in 2007. Over one-half of the total U.S. hydroelectric power is generated in three States (Washington, California and Oregon) with approximately 27% in Washington, the location of the Nation’s largest hydroelectric facility – the Grand Coulee Dam (2008, hydropower). Today, one-fourth of the electricity used throughout the world is generated with hydroelectric power. In total, hydroelectric power meets five percent of the global demand for energy. Hydroelectric power is used worldwide. Even in the Third World, large dams are being constructed as a quick rate. Some people are voicing concern that the new dams are increasing too quickly and threatening the local environment as a result (2009, Hydroelectric Power).
This map shows the amount of hydroelectricity produced in the world. The United States produces the most because of technology and abundance in supply of rivers. Africa and South East Asia are not able to produce much because of the lack of money and technology.
Currently
Are there places in the world better suited?
- Yes, specifically China, Brazil, the United States, Russia, Norway, India, Venezuela, Japan, Sweden, Paraguay, and France. These regions are major areas and are able to produce more efficient means of creating power.
Current examples include the Scottish Highlands, constructed during the early years of the twentieth century; the Grand Coulee Dam used for WWII planes and then led to generating power for the people; Suriname's Brokopondo Reservior, New Zealand's Manapouri Power Station; Iceland. There are also many small hydro-plants currently in China.
The Three Gorges Dam is the largest hydro-electric power station in the world and is located in China. The dam is 2,335 meters long and took around fourteen years to complete, the construction ending in 2008. There has been much controversy over this dam about the cost and benefits (2009, Three Gorges Dam). To read more about the dam, click on the following link:
[1]- Read about the controversy of the contruction of the Three Gorges Dam, which is now completed. This site includes the history of the river, the dam, and the comments and perspectives of those who are for and opposed to this constructed dam.
[2]- Duncan Graham Rowe speaks out about the controversial topic of hydroelectricity- the possible damages to the climate
In the Classroom
[3]- Students discuss sources of energy in the U.S. and participate in a mock hearing of the US Senate Committee for Energy and Natural Resources, choosing their roles.
[4]- Students learn about hydroelectricity and make a model of a water turbine.
Vocabulary
- Hydroelectric Power- power produced through the gravitational force of falling or flowing water
- Penstock- enclosed pipe that delivers water to hydraulic turbines
- Turbine- a rotary engine that extracts energy from a fluid flow
- Renewable energy-energy generated from natural resources.
Discussion
- How is electricity produced from flowing water?
- This is a controversial subject because some believe hydroelectric power is actually damaging to the environment. Do you agree? Why or who not?
- Where is the most hydroelectric power produced in the world?
References
(2009). Wikipedia. Retrieved February 15,2009, from Wikipedia: http://en.wikipedia.org/wiki/Hydroelectric_power.
(2008). Environmental Literacy Council. Retrieved February 18, 2009, from: http://www.enviroliteracy.org/article.php/59.html.
(2009). Wikipedia. Retrieved February 19,2009, from Wikipedia: http://en.wikipedia.org/wiki/Three_gorges_dam.
(2008). Hydropower--Energy From Moving Water. Retrieved February 19, 2009, from Kid's Energy Page: http://www.eia.doe.gov/kids/energyfacts/sources/renewable/water.html.
