Colorado-Big Thompson Project power plants generate an average of 770 million kilowatt hours of renewable energy per year. The C-BT Project’s West Slope pump plants annually use 70 million kilowatt hours. The remaining 700 million kilowatt hours are sold to customers in Colorado, Eastern Wyoming and Western Nebraska.
Power is generated by water flowing through C-BT Project power plant turbines to produce hydroelectricity. The power sold to customers is enough to supply approximately 68,000 homes for a year.
The C-BT Project has seven power plants. Six are located on the East Slope between Rocky Mountain National Park and the mouth of the Big Thompson Canyon. The Green Mountain Power Plant is located on the Blue River near Kremmling on the West Slope.
The newest plant, the Robert V. Trout Hydropower Plant, is at Carter Lake on the East Slope, and started generating electricity in May 2012. The Poudre Valley REA markets and distributes the power generated from the Robert V. Trout plant, which is the first power structure built, owned and operated by Northern Water. The Western Area Power Administration markets and distributes the power from the other six plants.
Power for the Pump Plant at Lake Granby
When the C-BT Project was planned in the 1930s, the East Slope and Green Mountain power plants were designed to provide power to the Willow Creek and Farr (previously Granby) pump plants due to a lack of sufficient power plants and electrical infrastructure on the West Slope when the project was built.
The Willow Creek and Farr Pump plants receive electricity from the East Slope power plants via a 69Kv transmission line extending through the Adams Tunnel. Today, even with adequate West Slope electrical infrastructure and power production, the Adams Tunnel transmission line still provides the West Slope pump plants with a portion of their electrical needs.
Plants Respond to Peak Power Needs
The East Slope hydroelectric plants also supply power for peak demands by using a system of forebays, afterbays and penstocks (large-diameter above-ground pipelines).
When peak electrical power is needed, such as early-evening hours, water is moved from a plant’s forebay (a small reservoir above a hydroelectric power plant) into a penstock leading to the power plant.
The force of the water moving through the penstock and turbine generates electricity. After the water passes through the turbine, it is typically released into the afterbay (a small reservoir located below a hydroelectric power plant).
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Water Descends 2,900 Vertical Feet
Water flows beneath Rocky Mountain National Park via the Adams Tunnel to the East Slope and descends the Front Range mountains nearly 2,900 vertical feet through these six power plants and four reservoirs:
Green Mountain Power Plant
- Mary’s Lake Power Plant and Mary’s Lake southwest of Estes Park
- Estes Power Plant and Lake Estes east of downtown Estes Park
- Pole Hill Power Plant and Pinewood Reservoir west of Loveland
- Flatiron Power Plant and Flatiron Reservoir southwest of Loveland
- Big Thompson Power Plant on the Big Thompson River west of Loveland
- Robert V. Trout Hydropower Plant at Carter Lake west of Berthoud
The Green Mountain Power Plant is located at the base of Green Mountain Dam at Green Mountain Reservoir on the Blue River southeast of Kremmling. The plant has a 25.8 megawatt capacity and was the first power unit of the C-BT Project to produce electricity. It began power production in May 1943.