Guemes Island Ferry Facts Coalition:

An Electric Ferry Is A Compromise

(This guest column appeared on page A4 of the Skagit Valley Herald (Opinion) on 2021-12-31.)

An electric ferry is a compromise

By Brent Morrison

Skagit County seems poised to build a new electric ferry.1 An electric ferry offers some benefits, but it also has some drawbacks because every design decision is a compromise.

Our commissioners resolved that the new Guemes ferry should be “safe, reliable and affordable” with “environmental benefits.”2 This column summarizes the design compromises in terms of these four traits, based on Skagit County’s publicly available reports3 and other credible sources. Cost and emissions comparisons were available for a 32-car ferry; the county later downsized to 28 cars.4

1. Safety. Skagit County’s emergency response standards are “easily achieved on a diesel-powered ferry” (Transportation System Assessment)5 but “difficult to meet” (Concept Design Report)6 on a battery-powered ferry because batteries store less energy than diesel does.7

2. Reliability. A diesel ferry8 is at least 50% more reliable than an electric ferry9 because diesel technology is proven, common and simple.10 Many of today’s electric ferries share their routes with other ferries, a road alternative or both.11 Guemes Island has one ferry and no road alternative.

3. Affordability. Relative to a diesel ferry, an electric ferry costs $6 million more to build, and it saves $3 million in lifetime operating costs, creating a net loss of $3 million.12 By trying to purchase the ferry entirely with state and federal funds, Skagit County may avoid the $6 million construction loss and pass the $3 million operating savings to the state agencies and ferry riders who ultimately pay the ferry’s operating costs.13 The electric ferry’s higher risk of cost overruns could undermine this forecasted savings.14

4. Environment. The existing ferry is loud because its engines sit on the main deck in acoustically leaky boxes. A new diesel ferry with engines below decks might reduce airborne noise,15 and a new electric ferry might minimize airborne noise,16 but its propellers are still the main source of underwater noise.17

A recent study of the existing ferry found that the crew’s exposures to engine-related air pollutants complied with state and federal guidelines, except for one exceedance caused by ambient organic carbon18 A new diesel ferry with carefully designed exhaust stacks might reduce onboard air pollutant exposures,19 and a new electric ferry might minimize onboard exposures.20 Downtown Anacortes enjoys “good” to “moderate” air quality 353 to 363 days a year,21 so an electric ferry may not measurably improve local air quality.

Electrification could eliminate most of the Guemes ferry’s operational carbon dioxide emissions if Puget Sound Energy follows its latest decarbonization plan.22 This great outcome may preclude an even better outcome because Skagit County is competing for limited funds.23

A project’s ability to combat climate change can be measured by the cost per ton of CO2 emissions that it prevents.24 The lower a project’s cost per ton, the more CO2 can be eliminated on a finite budget.

When we divide the electric ferry’s nominal life-cycle cost premium ($3 million) by the diesel ferry’s avoided lifetime operational CO2 emissions (54,000 tons),25 we get $56 per ton. At $11 to $37 per ton nationally ($23 locally),26 renewable electricity is one of many mature, scalable technologies that might do more for the climate.

An electric Guemes ferry offers lower operational CO2 emissions, quieter and cleaner air for crew and passengers and potentially lower fares. Yet it is also riskier, less reliable and costlier overall to American taxpayers. It may not be the most effective way to fight climate change today.

It is difficult to build what has been called “a ferry of tomorrow”27 while electric vessel technologies are still evolving.28 We could offer a test-bed for today’s technologies,29 although similar tests are already underway on more resilient ferry routes.

– Brent Morrison is licensed naval architect and marine engineer in Anacortes. He wrote this column on his own behalf.30


An Electric Ferry Is A Compromise [PDF]
The PDF version of this article contains the footnotes numbered here.

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