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Turn Off Yar Ships

The quiet case for plugging in container ships at port.

A container ship.
Heatmap Illustration/Getty Images

Everything has a cooler name when you’re on a boat. A kitchen becomes a galley. You’re not parked, you’re at berth. There is even a fun, old-timey name for cutting emissions when you’re at port by plugging into the local power grid: cold ironing.

Right now, lots of smart people are working to lower ship emissions, and for good reason: Container ships cart between 80% and 90% of global trade, yet more than 95% of them run on petroleum products (mainly an extremely dirty sludge called bunker fuel). By one estimate, a single large ship can emit as much CO2 as 70,000 cars, as much nitrogen oxide as 2 million cars, and as much fine dust and carcinogenic particles as 2.5 million cars. By another estimate, shipping pollution is responsible for 60,000 premature deaths per year. Though fully electrifying container ships remains distant and challenging for a number of reasons (albeit not for lack of trying), alternate fuel sources ranging from liquid natural gas to ammonia to hydrogen to nuclear propulsion to that oldie but goodie, wind, are all on the table.

Until that gets sorted out, though, container ships need to keep doing what they’re doing, which is moving stuff (we can all remember what happens when they don’t!). And that means the ships need to berth at ports to transfer their cargo, idling all the while with their auxiliary engines so the crew onboard has basic power for things like emergency equipment, lights, plumbing, temperature controls, and refrigeration. This is bad for all the same reasons a car idling for days on end would be bad if that car used the energy of a small town. It’s also bad for another reason that usually only gets mentioned in passing: Idling container ships are really, really loud.

The ‘Rio de Janeiro’ ship auxiliary generator noise at

When you hear about container ships being loud, it’s usually in the context of distressing whales. That’s because container ships are also noisy when they’re at sea, and most marine life depends on sound and sonar that gets drowned out by human activity. But much of the sound a ship at sea makes comes from its propellors, a design issue that will require solutions regardless of what kind of energy source is powering the ship.

At berth, though, container ships continue to make a racket. “During port stay, [the diesel generator] will often be the most predominant source of noise radiating from the ship to the surroundings,” a 2010 paper on noise pollution by the Danish Ministry of the Environment found. According to a report by Signol, a U.K.-based software company that markets its product as a potential solution for inefficient idling, “in close proximity to auxiliary engines, noise levels can reach 80-120 decibels — in comparison, a chainsaw averages 110 decibels!”

It’s a given that ports are loud: Idling ship engines join a cacophony of cranes, trucks, heavy machinery, trains, horns, and the like. Historically, this was fine, since ports were usually built away from residential areas, on land zoned for industry. But as cities grow more crowded, former industrial areas are becoming residential; some 39 million Americans lived near ports according to a 2016 EPA estimate, many of them people of color. “Complaints about noise from seagoing ships at berth are increasingly becoming an environmental issue ... mainly due to the rising population in residential areas around ports, the increase in the number of residential areas being built closer to the port itself, and changing expectations from people living in these residential areas,” explained the Noise Exploration Program To Understand Noise Emitted by Seagoing ships (NEPTUNES), a now-defunct collaboration between 11 ports in Europe, Australia, and Canada.

And whales aren’t the only mammals that hate ship noise. “Research on the effects of low-frequency noise has … shown that this is a stressor that can lead to headaches, dizziness, insomnia, depression, loss of concentration, and distortion of heart rhythm” in humans, the NEPTUNES report added.

Beyond health concerns, the noise is also just ... really annoying. In 2019, residents of Port Otago, New Zealand, were terrorized by what sounded like “a V8 running in your driveway” but were in fact 10-year-old container ships idling out in the harbor.

In Vancouver, in 2022, residents offered a similar simile for their acoustic tormentors: “It’s like having a garbage truck revving at the bottom of your driveway all day long,” one local told Vancouver Is Awesome.

When a supply-chain-related backlog forced container ships to idle off Seattle in 2021, an afflicted islander complained, “We’re getting the noise, the throbbing noise at night.”

Even in the best of circumstances, container ship noise is a persistent nuisance; some have even attributed a worldwide phenomenon called “the hum” to the racket made by container ship generators.

Everyone hates how container ships

Addressing the problem of ship noise, though, is tricky. There isn’t an international standard for how loud ships can be, and the most NEPTUNES was ultimately able to do was produce a list of unenforceable “best practices.” Many of the recommendations would also be tricky to implement on pre-existing vessels. While boats can be built to be quieter from the get-go, container ships are in circulation for decades; it might be 20 years or more before quiet fleets take over.

Ports also don’t want to rock the boat: “A strict noise policy is ... seen as a competitive disadvantage,” noted a 2013 study by Sweden’s Transport Research Institute (TRI), noting that shipowners must obey a long list of mandatory environmental regulations that they’re loathe to follow voluntary ones.

Thankfully for anyone who’s ever had to listen to the monotonous chuckling of a ship generator, two birds can be killed with one stone. Remember cold ironing? The term harkens back to the age of coal-fired ship engines: At port, the fires didn’t need to be fed, and the ship’s iron engines were allowed to go cold. Today, cold ironing refers to when a ship turns off all its engines at berth — including the smaller auxiliary ones belching sulfur oxide, nitrogen oxide, and CO2 over port cities — and instead plugs into onshore power (or “OSP,” in the industry lingo). “The overall emitted sound ... of a ship at berth could be reduced by up to 5 to 10 decibels by replacing the use of auxiliary engine(s) with external power suppliers,” NEPTUNES found.

In the EPA’s sexily titled “Shore Power Technology Assessment at U.S. Ports — 2022 Update,” the agency reported that there are currently 10 American ports that offer OSP for container and cruise ships, including the ports of Seattle, Tacoma, San Francisco, Los Angeles, San Diego, and Brooklyn (future upgrades are planned for Miami and Galveston). By all accounts, it’s working on both the environmental and the noise pollution fronts. “Port representatives report that neighbors notice when the shore power system is non-operational and vessels are emitting at-berth, compared to times when vessels are plugged in with no emissions coming from the vessel stacks and engine noise is reduced,” the EPA wrote. Unsurprisingly, “The community is strongly in support of the shore power system at the port.”

Cold ironing doesn’t reduce all port noise, of course; you can still expect the clanging of dropped containers, the vibration of ships, and the rumble of trucks and trains. There are other considerations, too: On-shore power generation needs to be low-emission, otherwise you’re just transferring pollution from the ship to the power plant. Still, the EPA is optimistic, noting that almost anything is better than ship engine emissions and that the situation will only improve as renewables roll out in force.

The possibilities only get more exciting from there. Stillstrom, a subsidiary of the Danish shipping conglomerate Maersk, is working on creating “charging buoys” that can power idling ships before they dock via underwater cables connected to offshore wind farms or onshore renewable power sources. OSP availability is rapidly expanding in the meantime. The Port of Seattle aims to install shore power at all of its major cruise and container berths by 2030. Starting this year, California will require 90% of vessels berthing at state-regulated ports to either use shore power or an approved emissions-reducing alternative. Abroad, the Port of Rotterdam is also working toward 90% shore power usage by 2030, and other European ports are pursuing OSP, too.

The impacts will be huge. The California Air Resources Board, for example, boasts its regulations will result in a 90% reduction in pollution from ships at port — and a 55% reduction in potential cancer risk.

That is, of course, great and worthy of pursuing in and of itself. “People will live longer, healthier lives” is a pretty unbeatable top line. But let’s not forget there are other laudable upsides to plugging in container ships — like living those longer lives in blessed peace and quiet.

Jeva Lange profile image

Jeva Lange

Jeva is a founding staff writer at Heatmap. Her writing has also appeared in The Week, where she formerly served as executive editor and culture critic, as well as in The New York Daily News, Vice, and Gothamist, among others. Jeva lives in New York City.


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