Bioenergy, Geothermal, Solar, Wind Power

Colstrip Transmission System Partners to Evaluate Upgrade to Accommodate Renewables

NorthWestern Energy announced that it and three other ownership partners in the Colstrip Transmission System (CTS) have agreed to proceed with a study of potential upgrades to the existing 500-kilovolt (kV) system in Montana. The system partners said that they will work together to identify and evaluate one or more potential system upgrades that may accommodate the transmission of wind and other renewable generation.

The CTS consists primarily of twin 500-kV lines that carry electricity from the companies’ jointly owned Colstrip power plants in eastern Montana to Townsend, Montana, where the CTS lines interconnect with the Bonneville Power Administration (BPA) transmission system. The CTS and BPA transmission lines ultimately deliver the Colstrip power to the customers of Puget Sound Energy, PacifiCorp, Avista and Portland General Electric. As part of the study agreement, the companies will begin discussions with BPA about a corresponding upgrade of its Montana Intertie transmission system between Townsend and Garrison, Montana, and points west.

“The Colstrip Transmission System was originally built almost 30 years ago to carry power from the coal-fired Colstrip plants. But times have changed, and it’s the growth and development of renewable energy that is the basis for the agreement,” said David Gates, vice president, Wholesale Operations, NorthWestern Energy.

The four utilities have agreed to share the cost to conduct a thorough and independent review of the power-transmission alternatives and potential ownership structures. The ownership structure of any upgrade option will be determined once projects are identified and agreed to by participating utilities.