New substation and equipment upgrades on high-voltage power lines linking the Northwest and Southwest will allow the two regions to share more surplus energy, strengthening the transmission grid, providing flexibility and allowing the regions to share affordable and environmentally friendly electricity.

The upgrades to the California-Oregon Intertie come as the Bonneville Power Administration is also upgrading and constructing high-voltage transmission lines within the Northwest to support the growth of renewable energy such as wind and ease bottlenecks in the system.

The California-Oregon Intertie is jointly owned by BPA, Portland General Electric and PacifiCorp. BPA owns most of the transmission capacity on this system and operates the COI. The lines have the capacity to carry 4,800 MW but before the upgrades often carried less energy due to operational constraints. These improvements will allow BPA to operate the line at the full 4,800 MW capacity much more frequently.

“Our electric connection to California and the Southwest is very important to us and our transmission customers,” said Brian Silverstein, senior vice president, BPA Transmission Services. “Strengthening that connection will ensure that we can get energy from where it is produced to where it’s needed. It’s as important as ever as thousands of megawatts of clean renewable energy sprout up across the west coast.”

Many customers have sought additional transmission capacity on the Intertie for several years, with pending requests totaling more than 3,000 MW, or the equivalent of three typical nuclear plants. These improvements will provide several hundred more megawatts of firm capacity on the COI and allow BPA and PGE to satisfy some of those requests.

The improvements also benefit the Pacific Direct Current Intertie—another high-voltage line that connects the BPA transmission system to southern California. The improvements will allow BPA to operate that line at its capacity of 3,100 megawatts more often as well.

The added transmission capacity may also help relieve generation oversupply situations such as the one the region just experienced this spring. This year, mild temperatures reduced demand and an abundance of hydro power boosted the supply. In this case, California did not need extra energy from the Northwest and the Interties were not fully utilized. However, the additional capacity could be very helpful during a year with warmer California spring temperatures and less water in the California hydro system.