what is hfo

Heavy Fuel Oil (HFO) is a category of fuel oils with a tar-like consistency, also known as bunker fuel or residual fuel oil. It is the result or remnant from the distillation and cracking process of petroleum. HFO is contaminated with several different compounds including aromatics, sulfur, and nitrogen, making emissions upon combustion more polluting compared to other fuel oils. It is predominantly used as a fuel source for marine vessel propulsion using marine diesel engines due to its relatively low cost compared to cleaner fuel sources such as distillates. HFO is highly concentrated in sulfur, with 35,000 parts per million, and is known to contain a range of toxins that cause multiple health issues. It is viscous and sticky, making it much harder than crude oil to pump or collect during a spill, often fouling habitats for years. HFOs are highly toxic when dissolved in water and exposed to sunshine, and they are difficult to clean up if spilled in the ocean as they do not readily disperse or breakdown in the marine environment. HFOs are also used as hydrofluoro-olefin (HFO) refrigerants, which are the fourth generation of fluorine-based refrigerants, categorized as having zero Ozone Depletion Potential and low Global Warming Potential, offering a more environmentally friendly alternative to other refrigerants.