The first all-electric tugboat in the US is about to launch

With their roaring diesel engines, tugboats push, pull and guide much larger vessels into port and out to sea. They are small but mighty — and incredibly dirty, spewing huge amounts of toxic exhaust and planet-warming emissions every year.

Now, however, the humble harbor craft is going electric.

America’s first fully battery-powered tugboat recently docked at the Port of San Diego, where officials are working to decarbonize not just tugs but also diesel cranes and trucks. The electric tug was built over three years at an Alabama shipyard, then moved through the Panama Canal before arriving in Southern California earlier this spring.

“We’re ecstatic,” Frank Urtasun, the port’s chairman, told Canary Media. ​“This electric tugboat is a real game-changer that I think will have ramifications across the country.”

The 82-foot-long vessel is set to begin operating within the coming weeks, as soon as the shoreside charging infrastructure is completed, according to Crowley. The Florida-based company owns and operates the electric boat — named ​“eWolf” in honor of Crowley’s first tug, the early 1900s Seawolf — and everything that’s needed to keep it running.

The eWolf is launching as ports and cities around the world are pushing to decarbonize their industrial waterfronts.

Globally, the cargo-shipping sector accounts for around 3 percent of total greenhouse gas emissions every year. While giant, oil-guzzling freighters tend to draw more public scrutiny for their large environmental impact, many thousands of smaller vessels and workboats are also major sources of both carbon emissions and local pollution.

In the U.S., state and regional policies are increasingly requiring operators to slash emissions from vessels, cranes, forklifts and other diesel-burning equipment. About 39 million people live in close proximity to ports, many of whom are lower-income residents and people of color.

An infusion of government funding has recently emerged to support those efforts. The 2022 Inflation Reduction Act includes $3 billion for zero-emission port equipment and infrastructure. The U.S. Environmental Protection Agency (EPA) is expected to announce the recipients of that funding later this year — along with the winners of a separate $115 million program under the 2022-2023 Diesel Emissions Reduction Act.

“I’m excited about the electrification of ports,” EPA Administrator Michael Regan said last Friday, speaking to reporters at an environmental journalism conference in Philadelphia. He noted that programs to clean up ports complement federal efforts to slash emissions from heavy-duty trucks on land.

The eWolf marks two important milestones for modern ports: It will curb emissions from an especially dirty vessel type, and it shows that electric tugs can work.

A first-in-the-nation effort to clear the air 

Tugboats present a particularly tricky challenge for electrification: The vessels need lots of power to operate, but they have limited space on board for batteries. Crowley and its technical partners, including ABB, said they figured out how to make it all fit.

The squat white tug uses a 6.2 megawatt-hour (MWh) battery system for its main propulsion and has two electric motors. When docked at the pier, eWolf will plug into the charging station, which is also a microgrid. The facility, which includes two 1.5 MWh batteries covered by solar panels, is also connected to San Diego Gas & Electric​’s power grid.

The idea is to allow the electric tug to recharge quickly during the day between operations, while also reducing bursts of high demand on the main electric grid, said Matt Jackson, vice president of Crowley’s advanced energy division.

“A lot of ports are at the end of the grid, and they can sometimes be unreliable” when it comes to providing a steady supply of power, he said. ​“We’re putting in a resilient system so that you can leverage this technology, reduce your emissions, but also be able to operate no matter what state the grid is in.”

The eWolf project, including the vessel and charging system, received nearly $14 million in local and federal grant funding, the bulk of which came from the San Diego County Air Pollution Control District. A Crowley representative didn’t disclose how much the electric tug cost to build overall. But the company said that the tug and microgrid together cost about twice as much as a diesel-powered tugboat of similar size.

Still, the electric tug is expected to be less expensive overall to operate and maintain than its diesel counterparts, since it uses electrical and computer-based systems instead of moving mechanical parts, said Coulston Van Gundy, vice president of Crowley’s engineering services. In certain places, the cost of electricity can be much cheaper than an equivalent unit of diesel fuel.

While eWolf is America’s first electric tug, existing initiatives are well underway to electrify passenger ferries, which have received earlier attention in part because the public interacts with ferries far more than they do workboats.

Washington State Ferries, the largest U.S. ferry system by ridership, recently began retrofitting the first of three diesel ferries with hybrid-electric systems, and it expects to bring its first fully electric ferry online in 2027. In San Francisco, local authorities are launching battery-powered vessels, as well as America’s first hydrogen-powered ferry. Crowley is working with ferry operators in the Northeast and Pacific Northwest to consider how and whether to convert their ferry fleets to plug-in hybrid or all-electric versions.

If the eWolf can spur a similar shift among tugboats, that would not only benefit the climate but also sharply reduce concentrations of health-harming pollutants. That includes particulate matter 2.5 (PM_2.5), which can increase people’s risk for cancer, and nitrogen oxide (NO_x) emissions, which can damage people’s lungs and trigger asthma symptoms.

In California, ​“Harbor craft are one of the top three cancer-causing risks to frontline communities near the Port of Long Beach, Port of Los Angeles, Port of San Diego and Oakland,” said Teresa Bui, the state policy director for Pacific Environment, an advocacy group. ​“And tugboats are a huge component of harbor craft emissions.”

While tugboats represent about 7 percent of commercial harbor craft in California, the vessels emit 19 percent of total PM_2.5 and 23 percent of total NO_x emissions within the maritime category, according to the California Air Resources Board.

Last year, the regulatory agency adopted a rule mandating cleaner engine upgrades for tugboats and workboats in California; it also requires that all short-run ferries in the state be zero-emission by 2026. However, the state agency can’t legally enforce the rule until it’s approved by the EPA. Pacific Environment and Democratic state lawmakers are urging the Biden administration to accelerate the review process.

Bui applauded the Port of San Diego for its first-in-the-nation electric tug. ​“It’s a great proof of concept,” she said of eWolf. ​“But it also shows that California is leading the way on cleaning up harbor craft.”

More electric port equipment to follow 

The Port of San Diego, for its part, said it’s been working in earnest to reduce pollution for nearly three years.

Spanning some 34 miles along the San Diego Bay, the port is a gateway for specialized cargo — including wind turbines, refrigerated fruit and cars — that is coming from or going to Asia and Latin America. In October 2021, the port’s board of commissioners adopted a clean air strategy focused on improving public health, particularly within the nearby communities of Barrio Logan and West National City.

“We identified in our inventory that the two main culprits of emissions in the port were from our tug operations and from our cranes,” said Urtasun, the port’s chairman.

As part of the clean air plan, the port began working closely with Crowley, the electric utility and other partners on the eWolf initiative. San Diego has 22 diesel tugs, and it’s working to cut diesel-related emissions from tugboats in half by 2030, including by transitioning to fully zero-emission or other less-polluting technologies.

Port officials are also phasing out a diesel-powered crane and replacing it with two all-electric mobile harbor cranes, as part of a larger goal to transition all diesel cargo-handling equipment to be fully zero-emission by 2030. And they’re developing a charging hub for electric drayage trucks, which move goods out of ports and onto highways, Urtasun said.

Crowley, meanwhile, said it has also considered designing next-generation options for battery-powered tugboats or similar models in other U.S. West Coast ports.

Going forward, electric tugs will likely cost less upfront to build than the eWolf as the battery technology improves for vessels, Van Gundy said. And project timelines will likely move faster as shipbuilders, port officials and the U.S. Coast Guard become more familiar with developing and permitting projects that are, for now, still first of a kind.

“On the land side, we’re seeing with electrification and battery systems that those prices are coming down,” he said. A similar trend is slowly starting to occur on the vessel side — but it’s happening overseas, especially in countries like Norway that are already replacing diesel engines with batteries in ferries and harbor craft.

“We are right at the precipe for that to begin here” in the United States, Van Gundy said.