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Bainbridge Island's existing electric system
Four transmission lines and three substations serve approximately 14,500 residences, businesses and other points of connection.
Bainbridge Island's existing electric system
Two high-voltage (115 kV) overhead transmission lines transport power across Agate Pass to Port Madison Substation. From Port Madison Substation, the Murden Cove transports power to Murden Cove Substation, and the Winslow transports power to Winslow Substation.
How power gets to you
Click through the slider to learn how power gets to you!
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Generation source
Electricity is generated at a place such as Wild Horse Wind and Solar Facility or Baker Dam.
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Transmission line
Transmission lines transport high-voltage power from the generation source to substations.
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Substation
These substations then step down power from the transmission voltage (115 kV on Bainbridge Island) to our distribution voltage (12.5 kV on Bainbridge Island).
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Distribution lines
A series of medium voltage (12.5 kV) distribution lines, overhead and underground, carry power from the substation to homes and businesses.
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Transformers
Transformers step down distribution voltage to service voltage. Transformers are the green boxes in some residences’ front yard or the barrel-like canisters on utility poles.
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Service line
Lower-voltage service lines, either overhead or underground, carry power to the meter on your home or business.Did you know Bainbridge Island has 322 miles of distribution lines, 56% of which (186 miles) are underground?
The Island’s electric system needs
In 2019, PSE completed a detailed assessment of Bainbridge Island’s electric system needs and identified the need for improved transmission reliability and increased capacity.
Improved reliability
Reliability means fewer power outages for customers – or outages that don’t last as long.
Bainbridge Island customers experience longer and more frequent outages in comparison to customers in Kitsap County and PSE company-wide due to:
Lack of redundancy
Nearly two-thirds of Bainbridge Island customers are at risk of a prolonged outage (as shown in the animation). This is because their area is served by a substation that’s fed by a single transmission line with no back-up. If the transmission line serving the substation goes out, then the substation and all customers served by that substation lose power.
Aging equipment
The Winslow Tap transmission line was built in the 1960s. Some of its poles and equipment are nearing the end of their life and need to be replaced.
Trees & difficult access
Bainbridge Island’s transmission lines are heavily exposed to trees. Trees cause most of the Island’s outages - when branches touch power lines or when trees fall into lines.
In particular, portions of the Winslow Tap transmission line are located in a heavily-vegetated corridor with difficult terrain and protected wetlands and streams, which makes it challenging to respond to outages compared to the other transmission lines on the Island.
Increased capacity
Capacity, put simply, is whether the electric system can meet power demand.
Electricity demand on Bainbridge Island is growing due to:
Population
Since the 1950s (when much of this electric infrastructure was built), the Island’s population has grown from just under 1,000 residents to nearly 25,000.
Increasing electrification
- Electric vehicle and appliance use has been growing on Bainbridge Island. We’re increasingly relying on electricity to power our daily lives, especially during the coldest and hottest times of year.
- Washington State Ferries is transitioning to a hybrid electric ferry system. This will require additional power for the Bainbridge Island ferry terminal.
“Winter peak” refers to the time in which the highest amount of electricity is used during the winter. Bainbridge Island’s winter peak occurs in the morning and typically on the coldest days of the year due to the increased use of heating.
A hybrid solution
In 2019, we announced our solution to address the Island’s electric system needs. We are taking a “hybrid” approach, combining new grid infrastructure and energy efficiency programs, to increase the Island’s electric reliability and capacity. PSE is committed to working with the community on implementing this hybrid solution.
Reliability
The following projects are intended to work together to make the Island’s electric grid more resilient and reduce the impact of outages by adding redundancy to the system.
- 1 New Murden Cove – Winslow 115 kV transmission line
- 2 Winslow Tap transmission line rebuild
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Upgrades at Murden Cove and Winslow substations
While not part of the hybrid solution, PSE made upgrades at Port Madison Substation in 2023 and 2024.
Capacity
The following project and program are intended to address the Island’s increasing power needs and reduce demand on the grid.
- Second transformer at Murden Cove Substation
- Flex Smart+ (demand response program)
Other projects
In addition to the hybrid solution projects, PSE is investing in other projects to improve Bainbridge Island’s distribution system reliability and capacity. Visit our website to check out our full list of current projects.
Conservation is key to helping PSE meet the Island's energy capacity needs. PSE proposes 3.3 MW of the Island's capacity need come from distributed energy resources (DERs) like PSE's demand response program, Flex Smart+. Learn more about Flex Smart+ on slide 8.
However, the demand for energy is growing faster than conservation efforts can keep up with, and conservation only helps in reducing capacity need. It doesn't address reliability.
*To meet this capacity goal, enough Bainbridge Island customers must participate in PSE's conservation and demand response programs. If there's not enough participation and we don't meet our 3.3 MW goal, PSE may need to add more infrastructure to support the Island's capacity needs.
Hybrid solution projects
Reliability | New Murden Cove – Winslow 115 kV transmission line
This project will improve reliability for two-thirds of the Island, including families, schools and businesses.
Overview
We plan to install a new 115 kV transmission line between the Murden Cove and Winslow substations to create a transmission loop. Each substation will connect to two transmission lines. If one line goes out, the other line can still feed the substation and provide power to customers.
Planning process
In 2019, we began seeking the community's feedback on siting the new transmission line through a Community Sounding Board, online community workshops, information sessions, an interactive route explorer and comment portal, mailings and more.
After more than two years of technical analysis and community engagement, we selected this route (shown on the map) because it best meets PSE’s operational needs while balancing community values shared during the engagement process.
The selected route follows PSE’s existing distribution system in the road right-of-way. This means we can collocate the transmission line over existing distribution lines, limiting impacts to private property and environmental resources.
Timeline
- Fieldwork and design: Ongoing through early 2025
- Real estate acquisition: Early 2025 through late 2026
- Permitting: Late 2026 through late 2027
- Construction: 2028 – 2029
New 115 kV transmission line
Want to learn more about the Murden Cove – Winslow 115 kV transmission line? Visit the project website.
PSE can underground transmission lines, but under PSE’s Electric Tariff G Schedule 80, underground transmission lines are considered a “local option” and the community must pay the cost difference between overhead and underground lines. Most communities decide not to invest in undergrounding transmission lines because they have other investment priorities.
If the City of Bainbridge Island is interested in cost sharing, we can explore that option. To-date, PSE has not received any indication that the City would like to pursue this.
PSE hosted a community-wide information session on undergrounding during the routing process for the new Murden Cove – Winlsow 115 kV transmission line. Check out our undergrounding transmission lines factsheet here to learn more.
Photo renderings
Please note, the photo renderings are for discussion purposes only and may change pending public, regulatory and utility review.
Location: Sportsman Club Road looking south from the north entrance to Woodward Middle School
Location: Sportsman Club Road Looking south toward the Sportsman Club
Location: High School Road looking east from intersection of Fletcher Bay Road and High School Road
Location: Fletcher Bay Road looking north along existing distribution near driveway for 6895 Fletcher Bay Road
Location: Fletcher Bay Road looking north along existing distribution line
Reliability | Winslow Tap transmission rebuild
This rebuild project will reduce the number and duration of outages, serving customers reliably into the future.
Overview
PSE plans to rebuild portions of the existing 4.5-mile Winslow Tap 115 kV transmission line. The Winslow Tap is the only transmission line serving the Winslow Substation, which supplies power to approximately 4,500 homes and businesses on the south end of the Island.
The transmission line was built in 1960 and certain equipment is nearing the end of its useful life and needs to be replaced. In addition, portions of the line are located in a heavily-vegetated corridor with difficult terrain and protected wetlands and streams, which makes it challenging to respond to outages.
We will replace some existing poles and equipment, install new wire and improve safety and access along the corridor. This work will reduce the number and duration of outages, serving customers reliably into the future.
Timeline
- Permitting: Ongoing through 2027
- Real estate acquisition: 2025 - 2026
- Construction: 2027 - early 2028
Existing Winslow Tap
Want to learn more about the Winslow Tap transmission rebuild? Visit the project website.
Reliability and capacity | Upgrades at Murden Cove and Winslow substations
Overview
To improve reliability, PSE plans to upgrade the Murden Cove and Winslow substations. These upgrades will support the new Murden Cove – Winslow 115 kV transmission line.
In addition, PSE plans to install a second transformer within the Murden Cove Substation to provide electric capacity to meet our customers’ current and future energy needs.
Timeline
Murden Cove Substation
- Fieldwork and design: Ongoing through 2024
- Permitting: 2024
- Construction: 2025 - 2026
Winslow Substation
- Fieldwork and design: Ongoing through 2024
- Permitting: 2025
- Construction: 2028
Want to learn more about the upgrades at Murden Cove and Winslow substations? Visit the project website.
Yes, there’s enough electric capacity coming onto the Island. Around ten years ago, PSE rebuilt and increased the electric capacity of the two transmission lines that carry power across Agate Pass to Port Madison Substation on Bainbridge Island. At the time, the lines were reaching their capacity limit.
With the increased capacity, these two transmission lines can reliably supply power to Bainbridge Island, even during times of high power usage or during an unplanned outage on another nearby transmission line.
What does a substation look like?
Capacity | Flex Smart+
Flex Smart+ is a voluntary energy efficiency pilot program for Bainbridge Island residents who heat and/or cool their homes with electricity. PSE launched the program in late 2022 to help meet the Island’s growing demand for energy.
How it works
- Ahead of extra cold or hot weather, we’ll adjust your smart thermostat’s temperature setting for a few hours. This is called a “Flex event.”
- Don’t worry, you’ll stay comfortable and you can always opt out. Flex events allow us to work together to prevent spikes in energy usage and smooth out demand.
- Get $75 for joining the program and up to $50 per thermostat you enroll, plus more for staying enrolled. You’re also eligible for higher rebates on heating equipment, insulation, windows and more to make your home more energy-efficient.
- Don’t have a smart thermostat? You can get a qualifying smart thermostat installed through Flex Smart+ with a $350 rebate.
Sign up now!
Visit Flex Smart+ and sign into your PSE account to see if you are eligible for the program.
PSE Flex Smart+
A flexible approach to meeting our region's growing energy needs.
We need your help!
To meet our 3.3. MW capacity reduction goal, enough Bainbridge Island customers need to participate in Flex Smart+ and PSE’s other conservation programs. If there’s not enough participation and we don’t meet our 3.3 MW goal, PSE may need to add more infrastructure to support the Island’s capacity needs.
Stay involved
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