HYDROPOWER

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Generating Unit Flyaround- video clip USBR.jpg

Fly Around Video Clip of Generating Unit

Water Intake Diagram.jpg

The Hydropower Resource

Glen Canyon Dam is the second highest (710 feet) concrete-arch dam in the United States, second only to Hoover Dam which stands at 726 feet. The 26.2 million acre-feet of water storage capacity in Lake Powell, created by Glen Canyon Dam, serves as a ‘bank account’ of water that is drawn on in times of drought. This stored water has made it possible to successfully weather extended dry periods by sustaining the needs of cities, industries, and agriculture throughout the West.

Hydroelectric power produced by the dam’s eight generators helps meet the electrical needs of the West’s rapidly growing population. With a total capacity of 1,320 megawatts, Glen Canyon Powerplant produces around five billion kilowatt-hours of hydroelectric power annually which is distributed by the Western Area Power Administration to Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada, and Nebraska. In addition, revenues from production of hydropower help fund many important environmental programs associated with Glen and Grand canyons.

The designation of Glen Canyon National Recreation Area in 1972, underscores the value and importance of the recreation benefits associated with Lake Powell and the Colorado River downstream of the dam. The GCNRA is managed by the National Park Service.

Glen Canyon Dam is the key water storage unit of the Colorado River Storage Project, one of the most complex and extensive river resource developments in the world. Without it, development of the Upper Colorado River Basin states’ portion of the Colorado River would not have been possible. [1]

LTEMP Resource Goal for the Hydropower Resource

Maintain or increase Glen Canyon Dam electric energy generation, load following capability, and ramp rate capability, and minimize emissions and costs to the greatest extent practicable, consistent with improvement and long-term sustainability of downstream resources.

Desired Future Condition for the Hydropower Resource

• Glen Canyon Dam capacity and energy generation is maintained and increased, so as to produce the greatest practicable amount of power and energy, consistent with the other DFCs.
• Ensure continued delivery of Glen Canyon Dam hydropower to the existing customers who have entered into long-term firm power contracts with WAPA.
• Ensure sufficient and efficient production of Glen Canyon Dam hydropower in order to provide the revenues to support the CRSP facilities and purposes.
• Maintain the operational flexibility (including but not limited to load following capability, ramp rates, and emergency operations allowances) that enable Reclamation and WAPA to meet the system operating and other regulatory requirements of WECC, North American Electric Reliability Corporation and the Federal Energy Regulatory Commission, as well as emergency operating criteria for safety and human health situations.
• Maximize the environmental benefits of hydropower generation at Glen Canyon Dam.
• Minimize carbon emissions through hydropower generation at Glen Canyon Dam.

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Hydropower - Online Training
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Updates

How does operations at Glen Canyon Dam fit into operations with other CRSP hydropower units?

What is Regulation and how does Glen Canyon Dam provide it?

As a control area operator, Western “regulates” the transmission system within a prescribed geographic area. Western is required to react to moment-by-moment changes in electrical demand within this area. Regulation means that “automatic generation control” will be used to adjust the power output of electric generators within a prescribed area in response to changes in the system frequency, time error, and tie-line loading, to maintain the scheduled level of generation in accordance with prescribed NERC criteria. The “record” used to calculate the degree to which Western is responding to these change on the transmission system is called the “ACE” - Area Control Error.

Hydro facilities such as Glen Canyon have an inherent design that allows them to respond rapidly to changes in power system demands. Other control area operators, across the nation, that do not have hydropower plants must either build small units (natural gas or oil-fired being the most likely) or add this capability to the design of larger units.

The transmission system that Western distributes power through is dynamic. Load requirements are constantly changing as a result of either the demands of the customers connected to it or changes that occur in other interconnected power systems. Western maintains the ACE signal to record its response to the fluctuations in system “loading”; (an effort to maintain a balance between power being consumed and power being generated - described above). If more demand is placed on the transmission system than is being generated, the resulting ACE is negative. Generators automatically respond to this condition by increasing generation. If demand is less than generation, ACE is positive. Generators automatically respond to this condition by reducing generation. The targeted ACE is zero.

The ACE signal that is sent to Glen Canyon where it is effectively added to, or subtracted from, the existing scheduled hourly generation base point. Therefore, at any moment during the day or night, Glen Canyon might be producing more or less power than the current hourly megawatt schedule.

The ACE signal is transmitted to Glen Canyon Dam every four seconds. The NERC requirement for regulation is that the ACE must “cross” the zero target every 10 minutes. The frequent “swings” in generation are described in the MOU signed by Reclamation and Western (4):

“These changes which occur many times during the hour are both positive and negative in relation to the schedule. The resulting output from Glen Canyon generators is an envelope of generation swings that are frequent, small in magnitude, the average of which approximates the original schedule.”[2]

In addition to daily scheduled fluctuations for power generation, the instantaneous releases from Glen Canyon Dam may also fluctuate to provide 40 megawatts (mw) of system regulation. These instantaneous release adjustments stabilize the electrical generation and transmission system and translate to a range of about 1,200 cfs above or below the hourly scheduled release rate. Under system normal conditions, fluctuations for regulation are typically short lived and generally balance out over the hour with minimal or no noticeable impacts on downstream river flow conditions.

Releases from Glen Canyon Dam can also fluctuate beyond scheduled releases when called upon to respond to unscheduled power outages or power system emergencies. Depending on the severity of the system emergency, the response from Glen Canyon Dam can be significant, within the full range of the operating capacity of the power plant for as long as is necessary to maintain balance in the transmission system. Glen Canyon Dam typically maintains 30 mw (approximately 880 cfs) of generation capacity in reserve in order to respond to a system emergency even when generation rates are already high. System emergencies occur fairly infrequently and typically require small responses from Glen Canyon Dam. However, these responses can have a noticeable impact on the river downstream of Glen Canyon Dam. [3]


Links and Information

WAPA Annual Reports

Presentations and Papers

2023

2022

2021

2020

2019

2018

2017

2016

2015

2013

2010

2009

Adding Generation to the Bypass Tubes

What does it mean that "generation of hydroelectric power is an incident of the foregoing purposes" in the 1956 CRSP Act (43 U.S.C. § 620)?

In GRAND CANYON TRUST vs U.S. BUREAU OF RECLAMATION, Grand Canyon Trust asserted that “[h]ydropower is an incidental benefit of every other stated purpose of the dam,” citing 43 U.S.C. § 620. Pl. Reply at p. 39. This is not a correct statement of the law. The relevant portion of 43 U.S.C. § 620 provides “for the generation of hydroelectric power, as an incident of the foregoing purposes.” Congress did not provide that hydropower is “incidental to” or “an incidental benefit of” the Colorado River Storage Project. Hydropower is an “incident of” the other Congressionally defined purposes. Used in this manner and in this context, the word “incident” means “related to,” or “resulting from,” and does not mean that hydropower resources are an “incidental” or minor authorized purpose of the Colorado River Storage Project. [1]

Ramp rates and beach stability

Alvarez and Schmeeckle (2013) that found that the erosion of sandbars (the primary reason we have ramp rate restrictions at Glen) are not affected by ramp rates themselves. They found that erosion of sandbars is primarily caused by the higher velocity flows that washes the toe of the sandbar away which then causes the rest of the sandbar to slough off and fall into the river (i.e. mass failure). Having flows come up or go down more quickly than they do now will not increase this rate of erosion aside from the fact that the faster you can come up and go down allows you more time on peak at those higher velocity flows, which was identified as the causal factor of sandbar erosion.

Other Stuff

GRAPH- GCD levels.jpg
Reservoirs Hydro ColoradoRiver.jpg
USBR- Q& A on GCD Hydropower