Cargo Ships: The Dirtiest Vehicles on Earth
by Tommy Monson


When the discussion of fuel efficiency and transportation emissions comes up in American politics, the first topic is always regarding cars. This makes sense; the transportation network in the United States is dominated by highways filled with passenger vehicles. During his time in office, President Obama made a point to raise the standards for fuel efficiency, setting a minimum of 54.5 mpg for cars and light-duty trucks by 2025.[1] Cars are possibly the most obvious sources of greenhouse gases that a typical citizen will encounter on a daily basis. However, even though these emissions are such a notable issue, they pale in comparison to emissions caused by a much different mode of transportation. Cargo ships, while not as ubiquitous as cars, release much more total emissions.


Cargo ships, huge vessels that carry containers full of goods internationally, emit a considerable amount of sulfur into the atmosphere. In fact, the amount of pollution generated by a single cargo ship is equivalent to that produced by about 50 million cars.[2] This means that only 15 cargo ships can produce the same amount of pollution as all of the cars in the world. These ships emit so much sulfur because they require so much fuel, nearly 289 million tons per year.[3] They are also designed to use the cheapest fuel possible, heavy fuel oil (HFO), which has a very high sulfur content of 3.5%.


Currently, the United States has established “Emission Control Areas” (ECAs), from the shore to 200 nautical miles out, in which cargo ships must burn fuel with only 0.1% sulfur composition.[4] This is accomplished either by switching from HFO to Ultra-Low Sulphur Marine Gas Oil (ULSMGO) within the ECA or by implementing exhaust gas cleaning devices, both of which are costly options. These ships are not designed to run on ULSMGO, as low sulfur fuels are not viscous enough and can actually wear a ship engine down prematurely. Additionally, considering how far these ships travel across the ocean, these ECAs are not a perfect solution.
Shipping is inherently a global issue. As of today, ECAs have been established all along the coasts of the United States, extending into Canada, as well as in the Baltic Sea and the North Sea. Beyond these waters, fuel oil burning is largely unregulated. Asia is especially problematic; both China and Japan employ cargo ships extensively, and yet have no regulations on controlling sulfur emissions close to shore. In order to combat this issue globally, the United States needs to spread its ECA initiative to Mediterranean countries as well as to East Asia.


Much can be done on a federal level as well. However, the United States cannot simply ban HFO-burning cargo ships. Most international trade is done on these ships, so a ban would be economically infeasible. In fact, in 2007 it was estimated that cargo ships transported about 60% of the total value of all seaborne trade. That means that the cargo shipping industry is worth more than $4 trillion.[5] The government could insist on the exclusive use of ULSMGO, but, in addition to the strain this would cause current vessels, it would increase the price of foreign goods significantly. As of mid-April 2017, the price of IFO380, a type of heavy fuel oil, is about $320 per metric ton whereas ULSMGO is closer to $500 per metric ton.[6] However, ship fuel efficiency is improving, so while a switch to low-sulfur fuel would cost the shipping industry nearly $12 billion per year, this cost would decrease over time. A switch to low-sulfur fuel would also save an estimated $36 billion per year due to improvements in public health.[7]


In order for effective improvement in emissions, the United States needs to enlist the help of other countries who import many goods on cargo ships. By implementing stricter worldwide regulations on shipping, certain effective strategies such as “slow steaming” can be utilized. Cargo ships are much more efficient when they travel very slowly, but there is ever-increasing pressure on ship operators to reach port as quickly as possible. Global speed regulations and appropriate fines supported by the United States will ensure that slow steaming can be implemented. The use of alternative fuels is also a viable economic option. Some newer cargo ships use liquefied natural gas (LNG), which burns much cleaner than traditional fuel oils. Since the introduction of tighter regulations on ECAs in 2010, it has become more expensive to maintain HFO-burning vessels that comply with both federal and global environmental policy.[8] Many shipping companies believe that LNG will become the most cost-efficient fuel due to this change. And while it is not possible to accrue enough solar or wind power to run a cargo ship, some vessels make use of Flettner rotors, which use wind to generate lift to drive the ship forward.[9] Electric cargo ships do exist, however the concept is still in its infancy. In 2015, Siemens created the Ampere, a 100% battery-powered car ferry.[10] Car ferries are not quite as large as cargo ships, but this is a significant step toward eliminating fuel oil burning entirely.


Cargo shipping emissions must be dealt with both on a federal level and a global level. The creation of ECAs was an important start in tackling this issue, and stricter regulations have made shipping companies consider fuels other than HFO. However, the United States needs to make an effort to convince European and Asian countries to implement their own ECAs. Domestically, it will soon become difficult to tighten ECA regulation any further, as it will put considerable economic stress on the shipping industry. The better option is to invest money in fuel technologies such as LNG and solar and wind supplementation. Clean fuels will then become the preferred option, and HFO-burning cargo ships will die out due to their own inefficiency.

[1] Office of the Press Secretary. “Obama Administration Finalizes Historic 54.5 MPG Fuel Efficiency Standards.” Obama White House. Accessed April 17, 2017.
[2] Wade, Chris. “Behemoths of Emission: How A Container Ship Can Out-Pollute 50 Million Cars.” Accessed April 17, 2017.
[3] United States Environmental Protection Agency. “Global Trade and Fuels Assessment – Additional ECA Modeling Scenarios.” Accessed April 17, 2017.
[4] United States Environmental Protection Agency. “Designation of North American Emission Control Area to Reduce Emissions from Ships.” Accessed April 17, 2017.

[5] Global Insight. “Valuation of the Liner Shipping Industry.” World Shipping. Accessed April 24, 2017.

[6] Ship & Bunker. “Global Average Bunker Price.” Ship and Bunker. Accessed April 17, 2017.

[7] AirClim, Seas at Risk, Bellona Foundation, North Sea Foundation, Transport & Environment, and European Environmental Bureau. “Air pollution from ships.” Accessed April 17, 2017.

[8] Fuel Freedom Foundation. “Maritime industry turns to alternative fuels.” Fuel Freedom Foundation. Accessed April 24, 2017.

[9] Fountain, Henry. “Building Greener Ships, to Keep the Sea From Rising.” The New York Times. Accessed April 17, 2017.

[10] Shahan, Cynthia. “World’s First All-Electric Battery-Powered Ferry.” Clean Technica. Accessed April 24, 2017.


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