Public Service Co. of Colorado applied May 6 to the Colorado Public Utilities Commission for a Certificate of Public Convenience and Necessity (CPCN) to upgrade and expand its Cabin Creek hydroelectric pumped storage plant.
This Xcel Energy (NYSE: XEL) subsidiary had applied in 2012 with the Federal Energy Regulatory Commission to renew its Cabin Creek license. FERC approved the application to relicense the facility in May 2014, with that decision covering the proposed projects described in this application at the Colorado commission.
The company wants to undertake two projects.
- The first project involves upgrading the existing pump turbine units, which will increase the overall generating efficiency and capacity of the facility by 36.6 MW, from 324 MW to 360 MW (called the “Upgrade Project). In addition to increasing the generating efficiency and capacity, the scope of work associated with the Upgrade Project will extend the life of the plant allowing it to operate for an additional 40 years, consistent with the renewed FERC license.
- The second project is to expand the size of the upper reservoir used to store the water needed for electric generation by raising the parapet wall (called the “UR Expansion Project”). The UR Expansion Project will provide an additional 75 acre-feet (AF) of storage capacity in the upper reservoir allowing for increased operation of the plant.
The Upgrade Project and the UR Expansion Project (together, the “Cabin Creek Project”) will provide an additional 112 megawatt hours (MWh) of energy generation per cycle (flow of water once through the turbine) plus 36.6 MW of capacity.
Cabin Creek, a pumped storage power plant, is located near Georgetown, Colorado, on Cabin Creek and South Clear Creek in Clear Creek County, high in the Rocky Mountains at an elevation of 10,018 feet above sea level. Cabin Creek has two units, which have been in operation since 1967 and are each capable of providing up to 162 MW of electric generating capacity. Water is supplied to the facility from the upper reservoir when in power generation mode and from the lower reservoir during pumping mode.
Cabin Creek contributes to the flexibility of the Public Service system because it is able to start quickly and to rapidly respond to changes in load particularly due to the variability of wind generation. As a result, Cabin Creek can be used to facilitate wind integration on the system, the application pointed out.
Cabin Creek requires a FERC license to operate because it occupies federal land within the Arapahoe National Forest, administered by the United States Department of Agriculture, Forest Service (USFS). A 50-year FERC license to operate the facility was originally issued in 1964. The new license authorizes the company to continue to operate Cabin Creek for an additional 40 years and to construct the proposed Cabin Creek Upgrade, thus increasing the authorized generating capacity of the plant to 336 MW. The license further authorizes the UR Expansion Project.
Total project cost would be a little over $89 million
Wrote Randy J. Larson, a Senior Project Manager in the Engineering and Construction Department at Xcel Energy Services, in May 6 supporting testimony: “We anticipate that the Cabin Creek Project will take 60 months in total to complete after the needed regulatory approvals. However, within that time period, the UR Expansion project will be completed in a 16-18 month timeframe. The total estimated cost will be approximately $89.3 million, which is comprised of $88.2 million for the Upgrade and $1.1 million for the UR Expansion Project.”
Larson added: “The Company will engage two separate contractors – one for the electrical work and the other for the pump-turbine work – who are experts in their specific areas. We will hire and have a separate electrical contractor on site at the same time to replace and/or refurbish the [balance of plant] electrical infrastructure including the excitation systems, transformer banks and the iso-phase buses and breakers. This electrical work is independent of the pump-turbine work. A separate pump-turbine contractor will then be engaged to concentrate on their area of expertise.
Mark G. Schultz. the Manager of Generation Control and Dispatch in the Commercial Operations Department at Xcel Energy Services, said in May 6 testimony: “A primary benefit that Cabin Creek provides to the system is the ability to store electricity generated during less expensive low load periods (when dispatched in pump mode) and release that energy (when dispatched in generation mode) during high load periods when the cost of incremental generation is more expensive. This typical cycle of daily operation allows the Company to capture a portion of the difference between marginal prices during low load and high load periods. This lowers the costs to all of our customers.”
Schultz later explained: “Cabin Creek is routinely used to meet a significant portion of Public Service’s operating reserve requirement. When the upper reservoir is full and both units are offline, Cabin Creek can carry 300 MW of non-spinning reserves. Each unit is capable of carrying up to 120 MW of non-spinning reserves while being dispatched in pump mode. When dispatched in generation mode at the operating minimum of 75 MW, each unit is capable of carrying up to 87 MW of spinning reserves. Cabin Creek, like other hydroelectric resources, is highly reliable in delivering timely generation when reserves are called upon.”