Rocky Mountain Power has proposed plans to acquire four wind farms in Wyoming, upgrade 13 existing wind facilities, and improve its transmission system.
The projects will cost about $3.13 billion and significantly boost the company's wind generation capacity.
The firm seeking approval from the Idaho Public Utilities Commission.
Rocky Mountain Power is also asking for approval of Certificates of Public Convenience and Necessity (CPCN). State law requires a public utility to obtain a CPCN before construction certain facilities or infrastructure.
Rocky Mountain Power's proposal calls for repowering, or upgrading, eight wind projects in Wyoming, four in Washington state and one in Oregon.
The facilities currently represent 999.1 megawatts of installed capacity, and the project is expected to increase generation between 11 percent and 35 percent.
Upgrades would include installation of higher-capacity generators and new rotors with longer blades, which produce more energy at lower wind speeds.
Overall, the company said, the repowering projects would lead to customer savings of between $41 million to $589 million, with natural gas prices and federal regulations representing the biggest variables.
And Rocky Mountain's proposal asks for CPCNs for four Wyoming wind projects with a combined capacity of 860 MW. Three have a capacity of 250 MW and one is capable of generating 110 MW.
The proposal also includes the construction of or improvements to several transmission facilities in eastern Wyoming. Most of the improvements are associated with the company's Energy Gateway West transmission project, which calls for the addition of approximately 2,000 miles of transmission lines in order to alleviate congestion on the transmission system, address growth and incorporate new generation sources such as wind.
The projects are mutually dependent, according to the company: The wind projects are not economic without the transmission projects, and the transmission projects are not economic without the wind resources.
The $2 billion cost estimate would lead to a rate increase of less than 1.9 percent in 2021, which is expected to be the first full year of operation of the new facilities, according to the company. However, Rocky Mountain Power said the work is expected to save $137 million in avoided costs through 2050, when the wind projects are fully depreciated.
And the transmission improvements outlined in the proposal:
- Construction of a 140-mile, 500kV transmission line running from Aeolus to Anticline, along with the construction of two new substations.
- Construction of a 5-mile, 345kV line connecting Anticline and Jim Bridger, near Rock Springs, and modifications to the Jim Bridger substation near Rock Springs.
- Installation of a voltage control device at the Latham substation near Wamsutter.
- Construction of a new 16-mile, 230kV line that would run parallel to an existing line from the Shirley Basin substation to the company's proposed Aeolus substation near Medicine Bow, in addition to modifications to the Shirley Basin substation, which is located near the junction of state highways 77 and 487.
- Reconstruction of 4 miles of a 230kV transmission line between the proposed Aeolus substation and the Freezeout substation, including modifications to the Freezeout substation, located between the Pine Draw and South Pine Draw.
- Reconstruction of 14 miles of a 230kV transmission line between the Freezeout substation and the Standpipe substation, which is near Hanna, including modifications to the two substations as required.