Frequently Asked Questions
Why is the Cascade Renewable Transmission Project needed for the Pacific Northwest?
To meet the climate crisis, Oregon and Washington have both passed into law bold clean energy requirements for electric utilities. As soon as 2030, 80% of electricity in Oregon must be carbon-free and 80% of electricity in Washington must be carbon-neutral. By 2040 and 2045, Oregon and Washington respectively, must achieve 100% carbon-free electricity. Without new transmission, achieving these clean energy goals will be impossible. That’s why this new transmission is urgently needed. Right now, there is minimal to no available east to west transmission capacity, stranding renewable energy capacity east of the Cascades and increasing overall energy demand.
This transmission line will transport 1,100 megawatts (MW) of renewable energy generated east of the Cascades to customers west of the Cascades – enough to serve roughly 800,000 homes. Overall, 5,000 MW of new renewable energy resources will be needed by 2030, the vast majority of which will be east of the Cascades where large-scale solar and wind generation can be built cost-effectively. This transmission line is a key part of securing the clean energy future.
What is a marine transmission line and what is the route of this proposed line?
Marine transmission carries electricity through an underwater cable. This proposed line is a single 12-inch cable bundle containing two 6-inch HDVC cables plus a fiber optic cable which will be buried 10-15 feet beneath the Columbia River riverbed from The Dalles to the Rivergate Industrial area in Portland. The 100-mile route will begin and end with 5-mile underground lines connecting to 5-acre converter stations located near existing Bonneville Power Administration (BPA) and Portland General Electric (PGE) facilities. The route bypasses Bonneville Dam, travelling 7.5-miles underground and around the dam and locks on public rights of way. Similar electricity transmission is used around the world and is currently in use in the San Francisco Bay Area and on the east coast. PowerBridge has built and now operates two such lines in the New York, New Jersey area..
Why go under the Columbia River and not above ground?
Marine transmission over long distances is a well-established, low-impact technology that has been used for more than four decades all over the world, including the United States, in rivers, lakes, and oceans. Compared to large structures needed for high-capacity overhead transmission lines, this line has the benefit of avoiding the visual and wildlife impacts of overhead transmission. In addition, the underground, underwater transmission will guard against power outages due to severe weather events and potential wildfires that could be caused by electrical equipment.
How does it work?
Renewable energy from large-scale wind and solar projects east of the Cascades will be transmitted to the eastern converter station (similar to a conventional substation) near The Dalles and converted from Alternating Current (AC) to Direct Current (DC) transmission. After completing its 100-mile route underground and under water, the line will connect to another converter station in the Rivergate Industrial Area in Portland and the energy will be converted to back AC for distribution to the electric grid, providing enough power for roughly 800,000 homes.
How is the line installed?
The 12-inch cable bundle is installed using a single barge and tug, typical on the Columbia River. Water jets create an 18-inch-wide trench in the river sediment, while the cable is laid roughly 10-15 feet below the riverbed. As the cable is installed, the natural sediment settles to cover the line. The cable installation vessels travel about 1.5 miles per day, so impacts to recreation in any particular area will be localized and very temporary. The entire project can be completed in 36 months of which 4-6 months is river installation. River installation will occur only during the late Fall and Winter months to avoid impacts on fisheries and river recreation. Cable installation will not occur when fish are migrating or spawning. The exact location of the line in the river is yet to be determined but will likely follow the navigation channel. The roughly 19-miles of installation outside the river will use conventional trenching or trenchless technology such as Horizontal Directional Drilling (HDD) and be done in existing roadways and public rights-of-way.
What’s the impact on the environment, particularly fish and wildlife?
To protect the environment, including fish and wildlife habitat, the entire project will undergo multi-year public reviews and will be required to obtain multiple federal, state, and local environmental permits in order to proceed. The project will be responsive to tribal governments, and qualified scientists and environmental specialists will advise each aspect of the project construction and operation.
Both underground and underwater cable installation will seek to minimize environmental impacts. Underground installation will use existing roadways and public rights of way without disturbing undeveloped areas or habit. Underwater installation will occur during the late fall and winter months to avoid impacts on fisheries, including migration and spawning.
For the past 15 years, PowerBridge has operated two similar marine transmission lines in the New York and New Jersey area with no reported adverse environmental impacts. In both projects, PowerBridge followed similar federal and multi-state permitting procedures.
Are there dangers to people or fish from electromagnetic fields (EMF)?
Multiple studies related to electromagnetic fields (EMF) have found no measurable adverse impacts on fisheries from similar marine transmission cables. A link to a report from Ocean Energy Systems, which includes a listing of relevant studies, can be found here.
Will this line impact public access to the river at any time? What about recreation and tribal fishing?
Except to enter and exit the river, the cable route will be kept well away from shoreline areas, including fishing sites. Installation will occur during winter months to minimize potential impact on recreation and tribal fisheries. A tug and barge, typical on the Columbia River, will install the cable travelling approximately 1.5 miles per day, so impacts to recreation in any particular area will be localized and very temporary.
Has this type of underwater transmission been installed anywhere else?
Yes. Underwater DC transmission has been used extensively in Europe to link power grids between countries and for offshore wind installations, and is currently being designed for offshore wind installations in the U.S. In addition to many underwater AC cables, there are four operating underwater AC-DC cable systems in the U.S. – three in the northeast and one under San Francisco Bay -- two of which were completed successfully by PowerBridge.
How do you know this will work?
PowerBridge has successfully developed, managed construction, and now operates two similar projects totaling 1,320 MW of transmission capacity, which were completed in 2007 and 2013. Follow-up studies have shown no adverse environmental impacts of operation. Construction and installation will be executed by highly experienced, global companies with track records established over decades. The entire project will undergo multi-year public reviews and will be required to comply with multiple federal, state, and local environmental permits in order to proceed..
What will this project cost and who will pay for it?
The estimated cost to build the entire project is $1.5 billion. No public investment is required for the construction, although PowerBridge is pursuing possible federal funding through the Inflation Reduction Act that was approved to boost green energy projects across the nation. At the peak of construction, the project will support 300-400 highly skilled union jobs. No state tax breaks are being sought and ultimately the project will generate revenues that will strengthen local tax bases.
Will the power transported on this line stay in Oregon and Washington?
Yes. Oregon and Washington are leading the way in meeting the climate crisis with laws requiring carbon-free electricity. This project will help both states achieve the goals of the clean energy laws they have passed. Without new transmission to move renewable energy generated east of the Cascades to customers west of the Cascades, achieving state clean energy goals will be impossible.
Are you communicating with government agencies and tribal governments?
Yes. In addition to the meetings required by government officials as part of the review and permitting process, we are meeting with tribal governments, and local, state, and federal officials to explain the project, respond to concerns and to seek input. We are also meeting with environmental, labor and community organizations to address specific issues and to explore partnerships that can benefit the environmental, social, and economic interests of the region. Our commitment is to engage openly, honestly, and respectfully with all local, state, federal and tribal governments along with the general public. We will respond to all questions as quickly as possible and if and when we don’t immediately have an answer, we will say so and seek out the information. .
