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IMO 2020 Reduces Sulfur Emissions, not CO₂

Our experts explain the changes and DHL’s GoGreen way forward


On January 1, 2020, the International Maritime Organization (IMO) introduced a new limit to the amount of sulfur that marine fuels can contain – a significant change for the ocean carriers and the entire logistics industry. 

The financial impact of IMO 2020 increased freight costs across geographies, and many environment-conscious shippers wonder why their shipments’ carbon dioxide (CO₂) emissions will not decrease with this change. 

Our DHL Global Forwarding experts explain the true environmental impact of IMO 2020 and how paves the way for the future of logistics.

Why Reduce Sulfur Emissions in Particular?


The engines of container vesselsemit sulfur oxide (SOx) when combusting fuel. SOx not only directly impact the health of the coastal communities living near major shipping routes, but it also deteriorates our environment.

As far as human health is concerned, SOx has been proven to increase cardiovascular diseases and strokes. It can also create pulmonary diseases. Lung cancer cases are soaring on coastal regions and asthma is affecting an increasing number of children. A 2016 study submitted to IMO’s Marine Environment Protection Committee (MEPC) estimated that reducing the sulfur dioxide emissions limit would help prevent 570,000 additional premature deaths worldwide between 2020 and 2025.

Sulfur negatively impacts our environment, too. The sulfur emitted acidifies water and our oceans, harming aquatic species and wildlife. And as clouds make their way back to the land, acid rain damages the soil of coastal regions, causing harm to crops and forests through acidification.

From 3.5% in the past, the new sulfur content limit in marine fuels is set at 0.5%, and as low as 0.1%  in designated emission control areas (ECA) such as the United States and Canada’s coastal regions. It will lead to a 77% drop in overall sulfur oxide emissions from ships – the equivalent to an annual reduction of approximately 8.5 million metric tons of sulfur oxide.

These efforts to reduce sulfur emissions – agreed to by the major global trade actors – represent a major humanitarian step forward in the fight against climate change.

How Ocean Carriers Reduce Their Vessel’s Sulfur Emissions and What Limits CO₂ Emission Decrease


Ocean carriers can choose between three different methods to reduce their container vessel’s sulfur emissions. While each solution offers a significant decrease in SOx emissions, they all come with concessions when it comes to CO₂ or other greenhouse gas emissions. They consist in either:

  • Using refined diesel fuels, or distillates such as marine gas oil (MGO), with sulfur contents below 0.5%. This fuel is more expensive than Heavy Fuel Oil (HFO).
  • Installingscrubbers on their ships – essentially a washing machine that separates the sulfur from the rest of the fuel when it is burnt.
  • Usingalternative fuel sources like liquefied natural gas (LNG). LNG requires adapted engines but is relatively cheaper to purchase. Because of the hazardous nature of gas, it restricts the types of cargo transportable on the vessel.

Studies diverge on the true environmental costs of IMO 2020’s sulfur emissions reduction way forward. Each sulfur reduction method comes with observable drawbacks that, while they do not outweigh the benefits of IMO 2020’s, justify further research and policymaking.

Switching to Sustainable Fuels with DHL Global Forwarding

By working with trusted partners, DHL can help customers not only reduce sulfur emissions, but also contribute to accelerating sustainable fuel production and global availability. Here is an example with Ocean Freight:

  1. DHL forecasts the carbon emissions which shall be reduced.
  2. The corresponding amount of sustainable marine fuel is ‘procured’ and used on one or several container vessels.
  3. Carriers bunker the sustainable marine fuel, but only need to cover the cost of the conventional fuel. The price difference between conventional and sustainable marine fuel determines the cost for the sustainable fuel premium.
  4. Applying the one-atmosphere approach simplifies the fuel switch, since the sustainable marine fuel does not have to be on the same vessels as the container whose emissions are to be reduced.
While conceptually this is a very straight forward exercise, each process step needs to be managed closely to ensure that the CO₂ reductions can be verified and claimed. This is exactly what DHL Global Forwarding is doing for its Customers with Book and Claim.

Low-Sulfur Fuels and Black Carbon

Not all low-sulfur fuels are created equal. Very Low Sulfur Fuel Oil (VLSFO) is obtained by blending additives and so-called aromatic compounds to enhance its efficiency and lubricity. These aromatic compounds, such as toluene or benzene, can create black carbon when in contact with the air.

Black carbon is an aerosol that results from incomplete fuel combustion, and the United Nations consider it to be a driver of climate warming, in addition to being toxic to humans. A study submitted by Germany to the IMO warns that the switch from sulfur-rich HFO to VLSFO may increase black carbon emission by up to 85%. The study also points out that operating ships at lower speeds may increase the emission of black carbon.

Scrubbers: Open or Closed Loop?

To comply with IMO 2020’s regulations, ship owners can install scrubbers onto their vessels. These scrubbers “wash” sulfur oxide off the vessels’ engine and exhaust systems, enabling for the usage of traditional HFO, with sulfur contents above 0.5%.

These scrubbers come in two categories: open- and closed-loop. Closed-loop systems store the waste water on the ship and require to be disposed of in dedicated port facilities. Open-loop systems, however, release the polluted water into the ocean, potentially harming ocean wildlife. Countries such as China are now considering enforcing policies that would ban open-loop scrubbers from their coastal regions going forward.

Liquefied Natural Gas (LNG): Methane, the Other Greenhouse Gas

While using LNG decreases a vessel’s CO₂ emissions, LNG essentially consists of methane – technically still a fossil fuel and a greenhouse gas. In addition to the reduction of CO₂ emissions, the United Nations’ Intergovernmental Panel on Climate Changerecommends reducing methane emissions by 35% or more by 2050, in comparison to 2010’s levels in order to contain global warming to 1.5° Celsius.

While the generation and distribution of LNG can raise CO₂ emission concerns, its normal combustion inside a ship’s engine creates less CO₂ emissions than that of HFO. However, suboptimal engine design enables leakage, also known as methane slip – the continuous emission of methane into the atmosphere. Such a phenomenon highlights the importance of better ship and engine design, along with thorough and regular emission measurement onboard. This is in part the objective of IMO 2050’s Initial Strategy, which addresses the points raised by the studies presented above – and shippers can already act today.

DHL’s Environment Protection Way Forward: Biofuels and IMO 2050’s Initial Strategy


Despite a degree of compromises observed above, IMO 2020 is paving the way for further global-scale environmental initiatives, many of them formulated in IMO’s 2050 Initial Strategy. Moreover, shippers have the power to reduce their environmental impact today – DHL Global Forwarding guides customers worldwide in the usage of biofuels, a viable alternative to fossil fuels.

Biofuels: Acting Today

Biofuels will remain one of the most realistic alternatives to traditional fuels, be they heavy or light in sulfur, for the next five to ten years. They must importantly be sourced from sustainable raw materials, but have the advantage to be widely commercially available today. With further supply chain optimization and economies of scale, they could be obtained at even lower prices in the future. When done correctly, both production and use of biofuels are also more environment-friendly, because the fuels are biodegradable and much less toxic than fossil fuels.

Biofuels commonly include:

  • Biodiesel: Derived from vegetable or animal fats and alcohol, it is generally used as an additive to diesel fuels, with the blend ranging from 2% (B2) to 100% biodiesel (B100). When made of waste feedstock (or HVO, for hydrotreated vegetable oils) it can be used as a pure fuel.
  • Bioethanol: It is used as an additive to conventional gasoline and usually produced through the alcoholic fermentation of corn or grain. The most widely known version is E10, used in passenger cars and in trucks, a blend of 10% ethanol and 90% gasoline.
  • Biokerosene: Also known as biojet, it is produced from vegetable and animal fats. Biojet fuels can reduce greenhouse gas emissions in aviation by anywhere from 50% to 95% compared to fossil jet fuel.

Biofuels exist in parallel to e-fuels, which are synthetic fuels produced from water and carbon dioxide. Read about e-fuels and other advancements in our Sustainable Fuels white paper PDF (1.9MB).

IMO2050’s Initial Strategy: Planning for Tomorrow

The efforts of the International Maritime Organization do not stop with sulfur emission reductions. An Initial Strategy has been planned out all the way to 2050, this time with a clear focus on greenhouse gas emission reduction.

As presented by IMO 2020, the next steps include:

  • Decreasing the carbon intensity of ships by designing better, more energy-efficient ships, by implementing their energy efficiency design index (EEDI) further.
  • Reducing CO₂ emissions by at least 40% by 2030, and by 70% by 2050, compared to 2008.
  • Reducing the total annual GHG (greenhouse gas) emissions by at least 50% by 2050 compared to 2008, Consistent with the Paris Agreement temperature goals.

Read more about the IMO Strategy

DHL Global Forwarding has been partnering with The GoodShipping Program since 2017 to offer a unique marine biofuel solution to shippers around the world. This is also why ocean freight remains the greenest way to ship your cargo today.

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