Container ships are some of the biggest polluters in the world. About 90% of the world’s trade occurs by sea on carriers that produce over 900 million metric tons of harmful emissions a year. Container ships produce about 3% of the total greenhouse gas emissions in the world, and the International Maritime Organization (IMO) estimates that that number could jump to about 20% in the next 30 years.
The shipping industry is starting to take notice of its own impact, and the concept of a green-shipping future has gained traction as a way to address pollution concerns. Green shipping is a collection of eco-friendly policies and technologies that have the potential to lower the environmental effect of global trade.
Here are some of the ways container ships pollute the environment, and how green shipping strategies plan to help clean up.
Massive cargo ships use heavy fuel oil, also known as bunker fuel or bunker oil, to transport over 750 million TEUs of freight a year. Heavy fuel oil is a high-carbon, high-sulfur fuel that releases harmful emissions into the air when burned. Heavy fuel oil is residually produced during the refinement of crude oil and isn’t as refined as the fuel used by cars. So while sea shipping is considered an extremely fuel-efficient method of cargo transport, the fuel that is used is considerably more harmful than the fuel trucks use. Studies on the environmental impact of heavy fuel oil show that emissions produced when the fuel is burned have adverse effects on the health of people living near trade lanes.
How it’s being addressed
While many countries have their own regulations for ships that sail into their ports, the IMO and its 174 member states unveiled plans to enforce a sulfur cap by 2020. The cap would require container ships to reduce fuel sulfur content -- a significant contributor to air pollution -- to 0.5%. The current cap is 3.5%. The Hellenic Shipping News estimates that the new policy will apply to 96% of the world’s shipping fleet.
Among the potential positive results of a sulfur cap, experts say cleaner fuels will lower premature ship-related mortality rates by 34%.
Ballast water is water carried by ships to improve stability. Ships fill ballast tanks near origin ports before heading out to sea to help them sail steadily on open water. Ballast water can have a major impact on any marine environment. The water taken on by ships in one region can severely pollute the waters in another, often by introducing foreign bacteria and harmful sediments, as well as invasive species of flora and fauna that wreaks havoc on a local ecosystem. A famous case of this is the introduction of the zebra mussel, native to the Caspian and Black Seas, to the Great Lakes system via freighter traffic in 1988. Since then, the invasive species has caused billions of dollars of damage while pollutants and viruses that it can carry have negatively impacted food chains.
How it’s being addressed
Ballast water regulations have been on the books for years now, with local governments dictating how the water should be treated as well as how it should be discharged when calling on a port in a given country. In the United States, for example, the National Invasive Species act in 1996, as well as Coast Guard and EPA policies over the last 10 years have been implemented to drastically reduce the environmental damage caused by ballast water. Since 2004, the IMO has taken measures to have all ships from member states develop ballast water management plans, a requirement that started being enforced in 2017.
The IMO’s plan requires ballast water treatment systems on all ships, which include physical filtration systems, ballast tank scrubbers, and chemical, thermal, or ultraviolet water treatment among other solutions. For more on the wide range of treatment methods, check out this comprehensive list here.
Of course, technology will be a part of the green shipping (near) future
Not surprisingly, a key component of a green shipping future is technology, of which the most notable use is alternative-power sailing solutions. Some supporters of alternative-power sailing have opposed the IMO heavy fuel oil regulatory plan. They argue that, instead of refining a toxic fuel source that will still be harmful to the environment (albeit with a reduced impact), heavy fuel oil dependency should be eliminated altogether in favor of clean energy sources.
These sources aren’t hypothetical solutions that are off in the distance. Solar and sail-powered liner technology is already available. China, looking to take the lead in alternative-power ocean freight solutions, began testing their first battery-powered ship last year: a freighter capable of carrying 2,200 tons of cargo per haul. Its battery can be charged in about the time it would take to offload its cargo load.
Separately, Rolls-Royce has been developing a fleet of autonomous, energy-efficient cargo ships that the company hopes to have deployed in the next seven to 10 years. They also started offering battery-powered ship engines earlier this year. While battery-powered engines work as a concurrent energy source (along with fuel for liners) today, Rolls-Royce believes the engines could eventually lead to all-electric liners in the very near future.
When people think about going green, they usually think about how things get made, how they get consumed, and what happens with the waste we produce. But "how things get around" is just as much a concern. And while it is extremely difficult to change manufacturing and consumption patterns, it's heartening to see that ocean freight is taking the lead, first by recognizing its role in the problem, but more importantly by doing something about it.
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