MARPOL ANNEX VI
The International Maritime Organization (IMO) was founded to promote more effectively safety at sea by forming an international body with the main shipping nations as members. Today there are 174 members from the most important maritime states.
Workgroups of the IMO discuss and agree on specific matters, for example, the Marine Environment Protection Committee (MEPC) is defining and regulating all gas and water emissions at sea. The IMO limited the Sulphur content of ship fuel to 0.5 per cent. Since January 2020, this regulation is applied worldwide.
In order to protect the oceans from SOx and NOx emissions from the engines, a regulation came into force for dedicated sensitive Sulphur Emission Controlled Areas (SECA) since 2015, on the North American coasts and in the North Sea and Baltic Sea. In these areas, the Sulphur content of fuel is limited to 0.1 per cent.
For both reglementations (0.1%S and 0.5%S) it is allowed to use High Sulphur Fuel Oil and use scrubbers to clean the exhaust gas to reach an equivalent level of Sulphur emissions.
Thus, the shipping companies are forced to bunker low sulphur fuels (LSHFO or MGO), to use alternative propulsion energy like LNG, battery power for electric engines, to install scrubbers to reduce the environmental footprint or to pay substantial penalties.