A pair of Connecticut companies are seeking approval to bury a 100-mile transmission line in the bed of the Columbia River to carry solar and wind energy to the Portland-Vancouver area.
On Wednesday, the U.S. Army Corps of Engineers issued a notice that the agency is extending the public comment period on Cascade Renewable Transmission’s permit application to Sept. 28.
Cascade Renewable Transmission is planning to build a 100-mile-long transmission line between Bonneville Power Administration’s Big Eddy substation in The Dalles, Ore., and Portland General Electric’s Harborton substation in Portland. The 1,100-megawatt line will run through Clark, Klickitat and Skamania counties in Washington and Wasco, Hood River and Multnomah counties in Oregon. It will consist of two 12-inch, high-voltage cables that will primarily be buried in the Columbia River via a hydro plow. Included in the project is a 7.5-mile underground bypass around Bonneville Dam.
The project is somewhat unusual in that it is being built by a private company. With an estimated cost of $1.5 billion, it’s a substantial investment in the region’s renewable energy grid, said Chris Hocker, Cascade Renewable Transmission’s chief development officer.
“Even though it’s a small slice of the transmission universe, there’s been an increasing number of projects that either have been built or have been proposed by entities such as ourselves that are neither utilities nor government agencies,” Hocker said.
Cascade Renewable Transmission includes two principal companies: PowerBridge, a green energy supplier, and Sun2o Partners, a renewable energy infrastructure developer. They hope to complete the permitting process by 2026 or 2027, with construction finished and the line in service by 2029, ahead of Washington and Oregon’s renewable energy goals in 2030.
Along with helping Washington and Oregon meet renewable energy mandates passed by lawmakers in recent years, the new line is intended to help meet the growing demand for energy — particularly clean energy.
“Where the most efficient, largest-scale renewable resources are all east of the Cascades, the load (consumption) is all west of the Cascades. The whole purpose would be to serve the greater Portland area, which includes Vancouver,” Hocker said.
By 2045, Clark County’s population is expected to grow to more than 718,000 residents. That’s an increase of more than 40 percent from the current population of 504,000, according to the 2020 U.S. Census. With that increase in population will come more single-family homes, apartments, commercial businesses, retail shopping centers and industrial developments — all of which will need electricity.
The Pacific Northwest Utilities Conference Committee’s 2024 regional forecast states the demand for electricity will increase by more than 30 percent in the next decade.
Cascade Renewable Transmission was first approached about the possibility of an underwater line about five years ago by a solar energy producer in Eastern Washington.
“They realized they could develop all of the solar they wanted but they didn’t have any place to put it,” he said. “So, they came to us and said, ‘Do you think it would be possible to use the river, as opposed to trying to bring in a whole new overhead line?’”
Hocker said the solar power company reached out to PowerBridge because of the company’s experience installing underwater transmission lines. PowerBridge built two of the United States’ four underwater transmission lines.
An overhead transmission line was proposed several years ago, but Hocker said it fell through after facing considerable opposition over environmental impacts.
“We know from our past experience that the process of installing the cable in the waterway is really pretty benign because of the method used,” Hocker said.
To install the transmission line, a ship or barge will tow the hydro plow. Water jets will create a 24-inch trench to bury the cables below the riverbed. The line will be buried away from wetlands and other environmentally sensitive areas along the shore.
“What we’re doing, as much as possible, is getting very, very close to the navigation channel and away from the shoreline. The more sensitive habitat areas and cultural resources areas are all near the shorelines, so we’re staying as close to the center of the river as we can,” Hocker said.
