NorthWestern Energy 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-kV system in Montana. NorthWestern Energy, Puget Sound Energy, PacifiCorp, and Portland General Electric 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 Colstrip Transmission System (CTS) consists primarily of twin 500-kV lines that carry electricity from the companies' jointly owned Colstrip power plants in eastern Montana to Townsend, Mont., where the CTS lines interconnect with the Bonneville Power Administration (BPA) transmission system. The CTS and BPA transmission lines ultimately deliver 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 between Townsend and Garrison, Mont., 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.

"This agreement is the logical next step in the development of this upgrade project," Gates said. "Montana's superior wind power potential combined with renewable portfolio standards in Washington and Oregon have spurred the renewed interest by the other owners to consider options for moving more of this new generation from Montana to the Northwest."

"Montana's great promise for wind power could significantly enhance the geographic diversity of wind resources in the Pacific Northwest, but only if we have the ability to move the power to where our customers live and work," said Sue McLain, senior vice president of Operations for Puget Sound Energy.

"Renewable energy resource areas can only reach their full potential when accessed by robust transmission capacity," said John Cupparo, PacifiCorp's vice president of transmission. "That's true for Montana and for other areas of the West where renewable resources are developing alongside traditional sources of power generation."

"Utilities in the Pacific Northwest are going to need more transmission capacity to handle growing loads and to integrate new renewables into the grid -- which will also be essential for us to make progress in reducing greenhouse gas emissions," said Joe McArthur, Portland General Electric's vice president for transmission and customer service. "This project is one of several major efforts region wide that show promise of helping us meet that need."

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.