Vineyard may be viable for electric ferries

Cost and fire safety remain concerns for a fully electrified ferry. 

The Steamship Authority board listened to a presentation on alternative propulsion systems during Thursday afternoon's Zoom session.

The Steamship Authority board learned Thursday afternoon that electric ferries are potentially viable for the Vineyard route. A team from Elliot Bay Design, the Seattle company that designed the Woods Hole, laid out facts and figures from a feasibility study on propulsion methods that showed that unlike the Nantucket-Hyannis route, the Vineyard Haven–Woods Hole route was suitable for an all-electric ferry. The Elliot Bay team used the Woods Hole as a model ferry for the study. The team tempered the possibility of electric ferry service with a handful of caveats, including the multimillion-dollar cost of batteries and shoreside electrical infrastructure, and the potential fire threat posed by batteries. 

An all-electric ferry was among a number of different propulsion methods evaluated for the study, including a hybrid option that appeared not to cut emissions to any significant degree. 

Lydia Benger of Elliot Bay said with a fully electric ferry, it is assumed that charging would be available in Woods Hole and Vineyard Haven.

Andy Bennett of KPFF Consulting Engineers, a company that assisted Elliott Bay Design in the study, said other propulsion options offered some greenhouse gas emission relief, but only all-electric all but eliminated those emissions.

Were electric ferries to be used on the Vineyard route, Bennett said, it was a “relatively short period” the vessels would need to draw charging power from the grid when at a terminal, and that power need not necessarily come directly from the grid if onshore batteries are installed. Bennett likened the batteries to a tank that can be drawn from by the vessels, but can be refilled at a slower pace due to the fact that ferries aren’t always docked and charging.

A “big deal” question is if local utilities can get power to the terminals, Bennett said.

Some sort of articulated arm would serve to plug the ferries to charging power, Bennett said. He said switch gears and transformers and other electrical components would be necessary, and he “strongly recommended” the connector cable be buried. 

Bennett said the batteries would be the equivalent of one or two shipping containers in size.

“It’s not just a battery,” he said. “It’s a battery/energy storage system. So it’s got controls in it. It’s got monitoring devices. It’s got built-in fire protection for the lithium ion batteries. They have a reputation for catching fire, which is well-known and much better understood, so it can be managed.”

Bennett showed where a battery facility, which he likened to an electrical substation, might be situated in Vineyard Haven. In Woods Hole, he said, a new cable that’s already planned could give the port a leg up in establishing electrical infrastructure. He specified that a feeder line is expected to be installed for the Woods Hole Oceanographic Institution, and it could also be used to handle a ferry’s electric power needs. 

“The good news is if these locations don’t work and you have to move it further away, at 12.47 kilovolts, you don’t have significant line losses in the transmission lines,” he said. “So they don’t have to be adjacent to the terminals. They could be further away.”

Bennett said the batteries needed aren’t cheap. “The bad news is it’s expensive,” Bennett said, describing them as costing “millions of dollars. It’s really expensive to get that battery energy storage system and the transformers that go with it.”

Without the onsite batteries, the SSA would need more power coming to the terminal, he said. 

“And what the utilities hate,” he said, “is this huge demand of a couple of megawatts of power that comes online when the ferry comes in, then as soon as the ferry leaves, that goes away … That cycle of very large energy uses, the utilities really hate that, and they’ll charge you a lot more for that. So the battery buffers that, and lets it be a more stable flow.”

Bennett said there is federal funding available to help with such an installation. “We know a lot of operators are looking for ways to pay for this, because it’s important that we do address the greenhouse gas emissions problem. Ferry operations across the board, around the world — everybody is working on this.”

SSA Vineyard representative Jim Malkin asked what the impacts of shore power have been at port communities in Washington and in “Nordic countries.” 

“Washington State Ferries, you hear a lot about that,” Bennett said. “We have not built anything yet. We’re still 100 percent diesel operations in Seattle, and we’re getting the same questions. In the Nordic countries where they do have this, most of the operations tend to be a little bit more remote, or smaller vessels, or in more of a developed port. It’s not so much like facilities that you have where the terminal is in the middle of a town.”

Bennett went on to say these operations endured some “hiccups.” Early on, Bennett said, there were brownouts, power surges. “And that was less than half the demand that we’re talking about. They learned from that. They were able to eliminate those issues. For better or for worse, in fact the Norwegians, they’ve done a lot more of this. They’re way ahead of us. They’re the ones learning the hard lessons, and we’re going to be able to benefit from that.”

Norway doesn’t use battery systems so much, Bennett said, having a “ton” of hydroelectricity and having “a much different structure for how their government and how their utilities work, so it’s much easier for them to get everybody on the same page and get power down to the terminal and make all that work.”

John Waterhouse of Elliot Bay Design said a contract has just been awarded for an Oslo-Hamburg route with the stipulation that “the last five to 10 nautical miles of the trip, the vessel will do it all on battery power so that the port community is not being impacted by the exhaust or the noise of the ship coming in. The trip between Oslo and Hamburg is too long a distance to do it all on batteries or electricity.” He also said electrification can do more than just reduce greenhouse gas emission, it can reduce noise pollution at ports and noise that may bother marine life. Some ferries in the region, he said, have an “orca mode” button to engage silent running when in the vicinity of killer whales. 

In response to another question by Malkin, Bennett said Washington State Ferries may not have any alternative propulsion systems yet, but hybrid ferries are under construction, and shoreside charging is being planned. 

“That’s fascinating, because that’s new news to me,” Malkin said. “Because a lot of my pro-electric fan mail points to Washington State as something we should be chasing, and some people here are under the impression that they are already electric.”

“That rumor,” Bennett said,”has reached not just the Woods Hoie community. We’ve heard the same thing from people in Maine.”

Asked if battery fires can be fought with water, Bennett said, “Probably not.”

He added that “one of the things that we’re running into [that] we would have to address to move forward is coordination with your local fire chief/fire department to make sure they’re comfortable with the access, the preventive measures, the alarms, everything associated with that, because it is still a risk that needs to be mitigated. Vessels like that — a fire at sea can really ruin your whole day. Vessel batteries are designed to a different standard. So there’s close coordination needed. There would be training needed for your local fire department to make sure they could respond if it doesn’t self-extinguish. That is a valid concern. It’s something that everybody is aware of …”

Nantucket board member Robert Ranney asked if ferries would need a special fire suppression system “in addition to what’s already there?” If so, he said, it would cost more money and take up more space.

Benger said battery fire suppression is guided by the registrar and classification society DNV, which has done some “significant testing on battery fires and the best way to suppress them.”

Benger said DNV recommended “watermist fire suppression” because it cools, extinguishes, and cuts off oxygen. “So we’ve been using that as the primary means of fire suppression for batteries,” she said.

In response to a question by Ranney about what backup power would look like, Benger said the electric ferry models would still require a traditional generator as a backup.

“You have to have two means of power,” Benger said. “In most of our designs to date where all-electric is the desire, we have two separate battery rooms to that redundancy and then depending on the customer’s comfort level, one to two generators. In some cases three.”

Overall, the major benefit to an all-electric ferry for the SSA appeared to be the elimination of the carbon emissions the diesel engines used presently generate. Aside from the infrastructure costs associated with developing ports and costs associated with retrofitting a ferry not purpose-built for electrical use, the operational costs of electric ferries were found in the study to be the highest of all propulsion methods studied — just shy of $18 million per year for a Woods Hole–type ferry. In contrast, a diesel version of the same ferry with new, “tier four” engines would cost just over $12 million a year. 

The board took the propulsion study under advisement.

In other business, the board voted unanimously to approve a procurement cost of $366,000 for electric charging stations in Hyannis and Falmouth. The stations would serve electric buses “that are due later this season,” SSA general manager Robert Davis told the board. The board also unanimously approved the purchase of two 21-foot shuttle buses for the sum of $217,324. Davis said the buses, which are diesel, would replace two compressed natural gas (CNG) buses on the Hyannis route. 

“Back in February of 2020,” Davis said, “the sole local CNG station, which was located in Yarmouth, closed permanently on rather short notice — as in we got out there, and the sign said we’re closed.” Davis said the SSA previously sold the CNG buses, and has been using larger buses on the route that are less efficient. He added that the construction of the buses will “piggyback” on a bus order from the state of Arizona. 


  1. why not develop tidal power in Muskeget Channel…build a floating charge station for ferries and other coastal vessels…I have the Tidal Power generator designed and ready to go into production…the charge station would become a gathering place…coffee shop…etc…the tidal generator would become the standard for ferries all over the world…all stemming from Edgartown…

  2. I am all for electric ferries. This article did a good job of explaining why a battery storage system at the terminal is necessary.
    The one thing opponents of any kind of electrical propulsion systems point to is the high cost, both financially and ecologically, of lithium ion batteries.
    But I get it–they are the battery of choice– if you are mobile…
    However, on the dock, flywheel energy storage is a much “cleaner” alternative, and competitively priced. They need little maintenance, will not catch fire, and are made of more inert materials, Unlike Lithium ion batteries, they have a nearly indefinite life span.
    They can be brought up to full power in a very short time span compared to Li-ion batteries.
    Also, if li-ion batteries become submerged in salt water during say , a storm surge, they are done. This video is rather boring until second 50.

    Here is a bit of an overview of the advantages and disadvantages of flywheels.
    It’s certainly worth looking at, given how we are trying to be “greener”

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