Skagit County, Wash., could become the first municipality in the U.S. to operate an all-electric vehicle ferry.

County commissioners are considering the merits of a detailed feasibility study prepared by EESI Marine to replace the existing ferry, which provides service between Anacortes, Washington and Guemes Island, with an all-electric, battery-powered vessel. The service provides 23 daily round-trips of approximately 30 minutes.

The study compared construction/installation costs of a battery-powered system that uses 600-hp electric motors to provide propulsion with those of a traditional engine-driven propulsion system (using a Tier 3, 600-hp engine). EESI Marine's projections showed that, while the equipment for the electric/battery version is more expensive, the simplicity of the electric installation and the elimination of the engines and supporting systems offset the battery and electric drive costs.

An electric ferry generates little noise pollution and zero emissions. Image credit: EESI Marine. In comparing annual operating expenses, current fuel and electrical power rates were utilized from the Pacific Northwest area, with engine maintenance costs obtained from the local engine supplier. Total outlays for the battery system included regular replacement of batteries (approximately every seven years), but minimal system maintenance. Annual operating costs for the electric option resulted in savings of roughly 50% over the engine-driven system, or $110k - $130k annually, the study concluded.

As to ease of operation, the electric ferry would require plugging into shore power between every round trip (twin 400A, 600V receptacles), with the ability to make four round trips in an emergency. However, trips to a fueling dock are eliminated, EESI Marine noted, as are the possibility of, and liability for, fuel spills.

The electric option generates little noise pollution and zero emissions, the latter which EESI Marine estimates would avoid over 500 tons of greenhouse gases annually. With elimination of the engines, vessel downtime is also expected to be reduced (battery cell replacements are expected to be conducted during the normal nightly shutdown periods).

The board of commissioners has not set a timetable for making a decision on the replacement.