Energy Education

Hydroelectric reservoir: Difference between revisions

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[[Category:Done 2021-01-31]]
[[Category:Translated to French]]
[[fr:Réservoir hydroélectrique]]
[[File:Hoover_Dam_Nevada_Luftaufnahme.jpg|400px|framed|right|Figure 1. The reservoir behind the Hoover Dam is called Lake Mead.<ref>Wikimedia Commons. (September 1, 2015). ''Hoover Dam'' [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/d/d8/Hoover_Dam_Nevada_Luftaufnahme.jpg</ref>]]
[[File:Hoover_Dam_Nevada_Luftaufnahme.jpg|400px|framed|right|Figure 1. The reservoir behind the Hoover Dam is called Lake Mead.<ref>Wikimedia Commons. (September 1, 2015). ''Hoover Dam'' [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/d/d8/Hoover_Dam_Nevada_Luftaufnahme.jpg</ref>]]


<onlyinclude>A '''hydroelectric reservoir''' is a large collection of [[water]] behind a [[hydroelectric dam]] that makes use of [[potential energy]] of water for [[electricity generation|generating electricity]].This water is held back by the dam, and is allowed to fall to generate [[electricity]] when it is needed.</onlyinclude><ref>Quebec Hydro. (September 1, 2015). ''Reservoirs'' [Online]. Available: http://www.hydroquebec.com/learning/hydroelectricite/gestion-eau.html</ref> These reservoirs are one type of water storage that is especially important to [[hydroelectricity]].
<onlyinclude>A '''hydroelectric reservoir''' is a large collection of [[water]] behind a [[hydroelectric dam]] that makes use of [[potential energy]] of water for [[electricity generation|generating electricity]].This water is held back by the dam and a small amount is allowed to fall down the base of the dam to generate [[electricity]] when it is needed.</onlyinclude><ref>Quebec Hydro. (September 1, 2015). ''Reservoirs'' [Online]. Available: http://www.hydroquebec.com/learning/hydroelectricite/gestion-eau.html</ref> These reservoirs are one type of [[water storage]] that is especially important to [[hydroelectricity]].


==Function==
==Function==
The water held in the reservoir of a [[hydroelectric facility]] is at a higher elevation than the rest of the dam. The height that this water is at is known as the [[hydraulic head]], and is one of the major factors in determining how much electricity can be generated. This is because the water, held at a higher level, has a certain amount of potential energy that is converted to the rotational motion of [[hydro turbine|turbines]] as it falls and spins the turbines blades. The higher the water is, the more potential energy it has and thus the more electricity can be generated. As well, the fact that this water is held up in a reservoir means that it moves down the dam through the [[penstock]]s effortlessly when gates are opened. This allows the amount of electricity being produced to [[dispatchable source of electricity|vary quickly]] based on demand.<Ref name="RE1">BrightHub Engineering. (September 1, 2015). ''The Components of Hydroelectric Power Plants'' [Online]. Available: http://www.brighthubengineering.com/fluid-mechanics-hydraulics/7120-components-of-hydroelectric-power-plants-part-one/?cid=parsely_rec</ref>
The water in the reservoir of a [[hydroelectric facility]] is held at a higher elevation on one side of the dam than the other. The elevation of this water is known as the [[hydraulic head]]. Usually measure in units of ''meters above sea level ([[masl]])'', hydraulic head is one of the major factors in determining how much electricity can be generated by a given dam. This is because the water, held at a higher elevation, has a certain amount of potential energy that is converted into the rotational motion of [[hydro turbine|turbines]] as it falls and spins the turbines blades. The higher the water is, the more potential energy it has and thus the more electricity can be generated. The fact that this water is held up in a reservoir means that it flows through the [[penstock]]s effortlessly under the force of gravity when gates are opened, which allows the amount of electricity being produced to [[dispatchable source of electricity|vary quickly]] to match demand.<Ref name="RE1">BrightHub Engineering. (September 1, 2015). ''The Components of Hydroelectric Power Plants'' [Online]. Available: http://www.brighthubengineering.com/fluid-mechanics-hydraulics/7120-components-of-hydroelectric-power-plants-part-one/?cid=parsely_rec</ref>


In addition to the water being held much higher than components of the dam such as the turbines, the water held in the reservoir is higher than the natural height of the water flowing in the river.
==Environmental Effects==
Although necessary for large-scale hydro projects the creation of reservoirs can have negative [[environmental impact|environmental effect]]s. The transformation of the river upstream of a dam into an artificial reservoir drastically changes the habitat of aquatic organisms. In this reservoir there are changes in water [[temperature]], [[chemical]] composition, and reduced [[oxygen]] levels (known as [[hypoxia|hypoxic conditions]]) which lead to [[environment]]s unsuitable for aquatic life that previously inhabited the river [[ecosystem]]. Most reservoirs host non-native and invasive species such as [[algae]] and snails, harming the ecosystem further.<ref>International Rivers. (September 1, 2015). ''Environmental Impacts of Dams'' [Online]. Available: http://www.internationalrivers.org/environmental-impacts-of-dams</ref>


==Environmental Effects==
Land that is covered when a reservoir forms contributes to [[greenhouse gas]] [[emission]]s, primarily [[methane]]. When previously uncovered land is transformed into a reservoir environment, organic matter from vegetation rots, producing methane. These greenhouse gas emissions are harmful to the environment, and contribute to [[climate change]].<ref>International Rivers. (September 1, 2015). ''Reservoir Emissions'' [Online]. Available: http://www.internationalrivers.org/campaigns/reservoir-emissions</ref> The emissions from hydroelectric facilities do tend to be lower than emissions from the [[combustion]] of [[fossil fuel]]s though. The environmental impact of hydroelectric reservoirs has partly contributed to growing interest in small-scale hydropower systems such as [[run-of-the-river hydroelectricity]]<ref>Watershed Watch Salmon Society. (June 6, 2020). ''Run-of-river Hydropower in BC'' [Online]. Available: https://www.watershed-watch.org/publications/files/RoR-CitizensGuide.pdf</ref>.
Although necessary for large-scale hydro projects (reservoirs and other [[water storage]] methods are not used in [[run-of-the-river systems]]) the creation of reservoirs can have negative [[environmental impact|environmental effect]]s. The transformation of the river upstream of a dam into an artificial reservoir drastically changes the habitat of aquatic organisms. In this reservoir there are changes in water [[temperature]], [[chemical]] composition, and reduced [[oxygen]] levels (known as [[hypoxia|hypoxic conditions]]) which lead to [[environment]]s unsuitable for aquatic life that previously inhabited the river [[ecosystem]]. Most reservoirs host non-native and invasive species such as [[algae]] and snails, harming the ecosystem further.<ref>International Rivers. (September 1, 2015). ''Environmental Impacts of Dams'' [Online]. Available: http://www.internationalrivers.org/environmental-impacts-of-dams</ref>


Additionally, land that is covered when a reservoir forms contributes to [[greenhouse gas]] [[emission]]s, primarily [[methane]]. When previously uncovered land is transformed into a reservoir environment, organic matter from vegetation rots, producing methane. These greenhouse gas emissions are harmful to the environment, contributing to [[climate change]].<ref>International Rivers. (September 1, 2015). ''Reservoir Emissions'' [Online]. Available: http://www.internationalrivers.org/campaigns/reservoir-emissions</ref> These emissions do tend to be lower than from the [[combustion]] of [[fossil fuel]]s though.
== For Further Reading ==
For further information please see the related pages below:
* [[Hydropower]]
* [[Hydroelectricity]]
* [[Hydrologic cycle]]
* [[Dam failures]]


==References==
==References==
{{reflist}}
{{reflist}}[[Category:Uploaded]]

Latest revision as of 21:24, 20 September 2023

Figure 1. The reservoir behind the Hoover Dam is called Lake Mead.[1]

A hydroelectric reservoir is a large collection of water behind a hydroelectric dam that makes use of potential energy of water for generating electricity.This water is held back by the dam and a small amount is allowed to fall down the base of the dam to generate electricity when it is needed.[2] These reservoirs are one type of water storage that is especially important to hydroelectricity.

Function

The water in the reservoir of a hydroelectric facility is held at a higher elevation on one side of the dam than the other. The elevation of this water is known as the hydraulic head. Usually measure in units of meters above sea level (masl), hydraulic head is one of the major factors in determining how much electricity can be generated by a given dam. This is because the water, held at a higher elevation, has a certain amount of potential energy that is converted into the rotational motion of turbines as it falls and spins the turbines blades. The higher the water is, the more potential energy it has and thus the more electricity can be generated. The fact that this water is held up in a reservoir means that it flows through the penstocks effortlessly under the force of gravity when gates are opened, which allows the amount of electricity being produced to vary quickly to match demand.[3]

Environmental Effects

Although necessary for large-scale hydro projects the creation of reservoirs can have negative environmental effects. The transformation of the river upstream of a dam into an artificial reservoir drastically changes the habitat of aquatic organisms. In this reservoir there are changes in water temperature, chemical composition, and reduced oxygen levels (known as hypoxic conditions) which lead to environments unsuitable for aquatic life that previously inhabited the river ecosystem. Most reservoirs host non-native and invasive species such as algae and snails, harming the ecosystem further.[4]

Land that is covered when a reservoir forms contributes to greenhouse gas emissions, primarily methane. When previously uncovered land is transformed into a reservoir environment, organic matter from vegetation rots, producing methane. These greenhouse gas emissions are harmful to the environment, and contribute to climate change.[5] The emissions from hydroelectric facilities do tend to be lower than emissions from the combustion of fossil fuels though. The environmental impact of hydroelectric reservoirs has partly contributed to growing interest in small-scale hydropower systems such as run-of-the-river hydroelectricity[6].

For Further Reading

For further information please see the related pages below:

References

  1. ↑ Wikimedia Commons. (September 1, 2015). Hoover Dam [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/d/d8/Hoover_Dam_Nevada_Luftaufnahme.jpg
  2. ↑ Quebec Hydro. (September 1, 2015). Reservoirs [Online]. Available: http://www.hydroquebec.com/learning/hydroelectricite/gestion-eau.html
  3. ↑ BrightHub Engineering. (September 1, 2015). The Components of Hydroelectric Power Plants [Online]. Available: http://www.brighthubengineering.com/fluid-mechanics-hydraulics/7120-components-of-hydroelectric-power-plants-part-one/?cid=parsely_rec
  4. ↑ International Rivers. (September 1, 2015). Environmental Impacts of Dams [Online]. Available: http://www.internationalrivers.org/environmental-impacts-of-dams
  5. ↑ International Rivers. (September 1, 2015). Reservoir Emissions [Online]. Available: http://www.internationalrivers.org/campaigns/reservoir-emissions
  6. ↑ Watershed Watch Salmon Society. (June 6, 2020). Run-of-river Hydropower in BC [Online]. Available: https://www.watershed-watch.org/publications/files/RoR-CitizensGuide.pdf
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