Fuel Oil Quality and Sulphur Caps

It was agreed that the sulphur content of any fuel oil used by ships should not exceed the 4.5% m/m (i.e. unit mass). This cap is slightly less than the 5.0% ISO specification and is consider to affect a small percentage (1% to 2%) of the residual fuel oil used by ships as illustrated below.

Ships operating in SOX Emission Control Areas (ECAs) must use fuel oil with a sulphur content not to exceed 1.5% m/m or be provided with an exhaust gas cleaning system to reduce the sulphur oxides from main and auxiliary engines to at least 6.0g SOX/kWh.

Fuel oils, other than coal and nuclear fuel, must be blends of hydrocarbons without inorganic acid (e.g., phosphoric or sulfuric acids) and derived from petroleum refining.