What is Heavy Fuel Oil?

On a technical level, HFO, which is often referred to as “refinery residual,” is a complex group of hydrocarbon products that consist of the highly viscous and tar-like residues of the crude oil refining process.[1] Not all HFO is chemically uniform as its components are present in varying percentages depending on the crude oil from which the residuals have been derived as well as the nature of any other products (including diesel) added in order to improve pumping/flow, handling and combustion,or reduce the sulphur content of the fuel (a technique known as blending).[2] That being said, HFO typically includes bitumen, asphaltenes and long chain polycyclic aromatic hydrocarbons.[3] Mineral pollutants such as sulphur and heavy metals (vanadium, nickel etc.), derived from the baseload crude oil, may also be present in relatively high quantities.[4] In addition, refinery residues consist of “heavy” compounds that are less prone to evaporation and distillation. By their nature and definition such compounds are less prone to degradation in the environment and are thus recognized as environmentally persistent.[5] Given the significant differences in the quality and content of HFO products currently available in the market, Annex 1 of the International Convention for the Prevention of Pollution from Ships (MARPOL) defines residual fuel as “oils, other than crude oils, having a density at 15°C higher than 900 kg/m3 or a kinematic viscosity at 50°C higher than 180 mm2/s.”

On a less technical level, HFO, which is the world’s dirtiest and most polluting ship fuel, is a tar-like residual waste from the oil refining process. As a result, marine transportation has been referred to as an incineration service for a waste product.[6] The combustion of HFO produces high levels of pollutants such as particulate matter, black carbon, sulphur oxide, nitrogen oxide, which have been linked to an increased risk of heart and lung disease as well as premature death. Black carbon is also a critical contributor to human-induced climate warming, especially in the Arctic.

[1] Deere-Jones, T., Ecological, Economic and Social Impacts of Marine/Coastal Spills of Fuel Oils (Refinery Residuals), at 6 (2016).

[2] Deere-Jones, T., Ecological, Economic and Social Impacts of Marine/Coastal Spills of Fuel Oils (Refinery Residuals), at 6 (2016).

[3] Vard Marine Inc., Fuel Alternatives for Arctic Shipping, Rev. 1, at 10 (2015), available at http://awsassets.wwf.ca/downloads/vard_313_000_01_fuel_alternatives_letter_final.pdf

[4] Deere-Jones, T., Ecological, Economic and Social Impacts of Marine/Coastal Spills of Fuel Oils (Refinery Residuals), at 6 (2016).

[5] Deere-Jones, T., Ecological, Economic and Social Impacts of Marine/Coastal Spills of Fuel Oils (Refinery Residuals), at 6 (2016).

[6] Vard Marine Inc., Fuel Alternatives for Arctic Shipping, Rev. 1, at 10 (2015), available at http://awsassets.wwf.ca/downloads/vard_313_000_01_fuel_alternatives_letter_final.pdf

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