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. But in addition to clean energy goals, the region is experiencing massive growth in future electricity needs for new technology centers, manufacturing, and electrification of buildings and transportation. Right now, there is minimal to no available east to west transmission capacity, stranding thousands of megawatts (MW) of renewable energy east of the Cascades.
The Cascade transmission line will transport 1,100 megawatts of renewable energy generated east of the Cascades to customers west of the Cascades. The vast majority of new renewable energy resources are located east of the Cascades where large-scale solar and wind generation can be built cost-effectively. This transmission line is a key part both of meeting future energy needs and securing a 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, and is widely used throughout the world.. 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 for about 80 miles between The Dalles and the Rivergate Industrial area in Portland. The entire route of nearly 100 miles 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 visual and wildlife impacts. In addition, burying the line underground and underwater will guard against power outages due to severe weather events and potential wildfires.
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 back to 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 ship or barge that tows an installation machine called a hydroplow. Water jets in the blade of the hydroplow fluidize the sediment to create a 24-inch-wide trench in the river bottom, 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 and fill the trench. The cable installation vessel travel about 1 mile per day, so impacts in any particular area will be localized and very temporary. The entire project (including converter stations) can be completed in 36 months of which 4-8 months is river installation. River installation will occur only during the late Fall and Winter months to avoid impacts on fisheries, habitat and river recreation. Cable installation will not occur when fish are migrating or spawning. The location of the cable bundle in the river will primarily be alongside the designated navigation channel in the center of the river, avoiding impacts to sensitive shoreline areas. 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.. The project will be responsive to tribal concerns, and qualified scientists and environmental and cultural resource 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 habitat. Underwater installation will occur during the late fall and winter months to avoid impacts on fisheries, including migration and spawning.
For the past 17 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 report from Ocean Energy Systems, which includes a listing of relevant studies, can be found here.
The cables are shielded so that they produce no external electric fields. Predictive models of EMF from the project’s cable bundle buried 10 feet below the river bottom show a very small increase in magnetic field strength directly above the bundle, rapidly decreasing at a few feet of distance above the sediment.
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 in four discrete locations, 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. Since cable installation will travel approximately 1 mile per day, impacts to recreational or other river use 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 $1.6 billion. Development costs and risks are borne by private investors; no public investment is required for construction, although PowerBridge is pursuing possible federal funding through the Inflation Reduction Act that is intended to boost green energy projects and strengthen the nation’s electric grid.. 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.
Instead of building new transmission, can’t we just conserve more energy and install small, distributed resources like rooftop solar? And what about building offshore wind?
Conservation, distributed energy, and offshore wind are a part of the solution, but only a very small part. Even when these alternatives are included, Portland General Electric (PGE) estimates its net additional resource needs to be more than 1,100 MW by 2030, ramping up to more than 4,000 MW by 2040. Note also that offshore wind, while larger in scale, has technological, cost, permitting, and transmission challenges that make it unlikely to be implemented before the mid-2030s.
