It’s no secret electric reliability on Bainbridge Island needs to be improved. In finding solutions, PSE committed to exploring new technologies. Our proposed plan is a unique solution designed for Bainbridge Island – combining new technologies and grid infrastructure to ensure safe, dependable power for families and businesses for years to come. We will partner with the community to implement these solutions.
PSE’s proposed solution
Our proposed plan is a unique solution crafted for Bainbridge Island. The project package combines new technologies and grid infrastructure to ensure safe, dependable power for families and businesses for years to come.
These projects are designed to:
- Improve electric service reliability, reducing the frequency and duration of power outages for customers on Bainbridge Island.
- Successfully meet the increasing power needs of Bainbridge Island for years to come.
- Support the electrification of the Washington State Ferries.
- Deploy new technologies that will help postpone building a new substation. These technologies maximize opportunities for conservation and innovation and may help reduce our carbon footprint.
PSE will continue to invest in projects to improve reliability on the distribution system that serves neighborhoods.
Solutions components
- Construction at Bainbridge Island substations
- Winslow Tap Transmission Rebuild
- Murden Cove – Winslow 115 kV Transmission Line
- Ferry Electrification
- Battery Energy Storage System
New transmission line and rebuild the aging Winslow Tap to improve reliability
New 3.3 MW battery energy storage system to add additional capacity
Targeted conservation and demand response tools to reduce demand
Bainbridge Island solutions package components timeline and milestones
Electric reliability on Bainbridge Island needs to be improved. PSE’s customers have been vocal in asking us to find solutions that improve reliability, meet this community’s growing energy needs and align with the community’s values.
PSE recently completed a detailed assessment on Bainbridge Island’s electric system needs. The Needs Assessment identified known and new issues.
PSE and third-party experts then developed a Solutions Report to analyze potential solutions to meet these needs. The report studied the feasibility of both traditional wires solutions and innovative non-wires solutions.
The Need Assessment identified three key findings:
- Poor transmission reliability
- Aging infrastructure
- Growth: ferry electrification and increased demand for power
Poor transmission reliability
The Needs Assessment affirmed that the island has a transmission reliability need. The study highlighted that Bainbridge Island customers experience more frequent and longer outages than the average PSE customer, and nearly half of those outage minutes are due to issues with the transmission system. Some specific challenges to reliability include:
- Trees: Bainbridge transmission lines are heavily exposed to trees, and 64 percent of outages are caused by trees.
- Radial transmission lines: Nearly two-thirds of Bainbridge customers are at risk of a prolonged outage. This is because their area is served by a substation – either Winslow or Murden Cove substation – that’s fed by a single transmission line with no back-up.
- Customers served by the Winslow substation have the worst reliability on the island, and secondarily Murden Cove substation.
- Nearly 70 percent of transmission customer minutes of service interruptions were from the Winslow Tap transmission line that feeds the Winslow substation.
Aging infrastructure
Inspections determined that portions of the Winslow Tap circa-1960 transmission line are nearing the end of its useful life and needs to be replaced. In addition, the Winslow Tap is in a heavily vegetated corridor with difficult terrain, which makes finding and repairing outages challenging and results in longer outages.
Substation capacity need
Ferry electrification and the community’s growing energy needs are driving the need for additional substation capacity, particularly during winter peaks.
- Increasing demand: The population of Bainbridge Island has increased significantly over the last few decades and electric demand has changed. Even with energy conservation, the electric demand residents place on the system has dramatically increased.
- Ferry electrification: Soon Washington State Ferries will be electrified to cut carbon emissions and reduce pollution, which will require a charging system at Bainbridge Island and creates even more demand.
We’re investing in transmission infrastructure that will make Bainbridge Island’s electric grid more resilient and reduce the impact of any single outage by focusing on redundancy.
New transmission line
- We’ll add a new transmission line between the Winslow and Murden Cove substations to create a transmission “loop.” This means each substation will be connected to two transmission lines. If one line goes out, the other line will still feed the substation and provide power to customers.
Rebuild the aging Winslow Tap
- We’ll also replace aging infrastructure and improve the utility corridor on Winslow Tap, a critical transmission line that serves the south end of the island.
PSE is committed to partnering with our customers for a better energy future. Batteries and distributed technologies are an important part of that equation for our Bainbridge Island customers.
To address the growth that’s straining the island’s distribution system and balance the values of the community to limit infrastructure, PSE is proposing to postpone a new substation and instead:
- Install a utility-scale battery energy storage system at the Murden Cove substation. The 3.3 MW battery will add capacity to the system by supplying electricity during winter peak periods when demand is high.
- Implement innovative conservation and demand response programs that help lower customer demand in various ways. This may include partnerships with customers to lower their energy use during periods of peak demand by using smart thermostats and other tools. Learn more about our plan for deploying targeted conservation and demand response on Bainbridge Island by watching this webinar.
- We’ll work with Washington State Ferries to curtail their use during peak periods when they begin their electricified ferry runs.
If all of the non-wire solutions are successfully implemented, we’ll postpone the need for a new substation for at least 10 years.
PSE’s goal is to improve your reliability and modernize the grid. We’re in the early stages of these projects. While they each have their own timeline with opportunities for involvement, we anticipate having:
Targeted conservation/demand response tools deployed
2022-2030
Battery in-service
2026
Winslow Tap rebuilt
2027
Transmission line loop built
2028
- Community meeting slide deck, October 2019
- Community meeting summary, October 2019
- Information sheet, October 2019
- Needs Assessment, July 2019
- Solutions Report, July 2019
- Undergrounding transmission lines factsheet
- Information Session #1, Targeted Conservation and Demand Response, January 2020
- Murden Cove – Winslow Tap 115 kV Transmission Line project factsheet, December 2020
- Murden Cove – Winslow Tap 115 kV Transmission Line Route Options factsheet, June 2021
- Information Session #2, Underground Transmission Lines, August 2021
- Information Session #3, EMF, September 2021
- Murden Cove – Winslow Tap 115 kV Transmission Line Selected Route factsheet, December 2021
- Bainbridge Island Transmission and substation outage summary, 2013 – 2022
