Marine fuels (marine fuels / bunker fuels)

Marine fuels, also known as bunker fuels or marine fuels, are products that are used as fuels in shipping. They are produced from crude oil in refineries by fractional distillation and are subject to globally defined standards such as ISO 8217.

Definition of marine fuels
Marine fuels are mineral oil-based fuels used in shipping for diesel engines and boiler systems. They are divided into two main categories: Residual oils and distillate fuels, which have different physical and chemical properties and are subject to specific quality requirements.

Background / Origin
Marine fuels are produced by the fractional distillation of crude oil, in which the crude oil is heated in stages to obtain different fractions. The International Maritime Organization (IMO) has had the ISO 8217 standard in force since 1987, which defines the requirements for these fuels. This standard divides marine fuels into residual fuels and distillate fuels and defines the quality parameters.

The development of these standards is the result of environmental requirements that have become necessary due to the increasing emissions of sulphur oxides and nitrogen oxides in shipping. These emissions are particularly high because many ships are operated with heavy fuel oil (HFO), which has a high sulphur content. The IMO has therefore taken measures to regulate emissions through stricter limits and to promote the introduction of lower-emission alternatives, such as LNG.

A major change in the shipping industry has been the global restriction of sulphur content in marine fuels to 0.5% from January 2020, which is the biggest change since the switch from coal to oil. This development is part of a comprehensive strategy to improve the sustainability of the shipping industry.

Properties
Marine fuels are made up of different fractions of crude oil, which are separated by fractional distillation. The basic properties are:

- Composition: subdivided into residual oils (e.g. LSFO, ULSFO, HSFO) and distillate fuels (e.g. DMA, DMX, DMB, DMZ).
- Physical characteristics: Residual oils are more viscous, while distillates are more fluid and of higher quality.
- Quality differences: Residual oils are classified into six types according to kinematic viscosity (e.g. RMG 380). Higher viscosity indicates lower quality.
- Chemical characteristics: Heavy fuel oils have a high sulphur content, while distillate fuels generally have a lower sulphur content and are used in emission-critical areas.

Application and importance in the market
Marine fuels are crucial for the operation of ship engines and are widely used in the shipping industry. They are used in both large transportation vehicles and smaller boats. Large ships often use heavy fuel oil, while smaller ships usually use light distillate fuels.

Compliance with the regulations for reducing emissions in Emission Control Areas (ECA) forces ship operators to use low-emission fuels. The ISO 8217 standard plays a central role by defining the quality standards for various marine fuels.

The market is showing a trend towards LNG as an alternative fuel due to its better CO2 balance and lower pollutant emissions compared to traditional marine fuels, even if internationally binding standards have not yet been established.

Differentiation from similar terms
- Marine Diesel (MDO): Mainly used for ships with a low heavy fuel oil content. In contrast to heavy fuel oils, MDO has a lower viscosity and better combustion behavior.
- Intermediate Fuel Oil (IFO): Blends of residual oils and distillates, often used in larger marine applications. IFO differs in the combination of fuels and their physical characteristics.

Summary
Marine fuels are essential fuels in the maritime industry. They are divided into main categories based on their physical and chemical characteristics. The international standard ISO 8217 specifies the quality requirements and requires the shipping industry to reduce emissions. In response to increasing environmental regulations, the importance of alternative fuels such as LNG is growing, although rules on use and storage are still being developed. The transition to low-emission fuels marks a significant change in ship refueling.