Colman Dock Electrification

Seattle City Light, WA

To reduce reliance on burning petroleum products and the resulting carbon impacts, Washington State Ferries will convert ferries serving Colman Dock in Seattle to electric plug-in hybrids. The ferries are in port for a short time and need a significant power supply to recharge their batteries. To help draft a service plan, Seattle City Light (SCL) turned to Perteet to develop and assess electric service alternatives to charge the hybrid-electric ferries. The Perteet team evaluated and compared feeder capacities, electrical loads and routings, the addition of shoreside battery energy storage systems (BESSs), equipment sizes and layouts, and scaling for future needs.


  • Energy
  • Planning

The analysis included several meetings with existing stakeholders to assess their future needs.  The assessment concluded with a report summarizing findings, and a recommended solution consisting of a primary feeder, a backup feeder, and a BESS to serve the ferry system’s high peak load demands, as well as provide redundancy for the electrical system in the area.  The BESS would be the first of this technology deployed by SCL.


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