Marine Fuel Glossary

Fuels and grades

• VLSFO — very low sulphur fuel oil, ≤0.50% S.
• HSFO — high sulphur fuel oil, typically ~3.5% S, used with exhaust gas cleaning.
• ULSFO — ≤0.10% S residual fuel for emission control areas.
• MGO / DMA — marine gasoil, a distillate grade.
• Bio-blend — conventional fuel blended with a biofuel component, commonly B24 or B30.

Quality and testing

• Cat fines — aluminium and silicon catalyst particles that cause abrasive engine wear.
• Compatibility — whether two fuels can be commingled without precipitation.
• Off-spec — a delivery outside contractual or ISO 8217 parameters.
• MFM — mass flow meter, used to measure delivered quantity at some hubs.

Commercial terms

• Stem — a confirmed bunker order and its delivered quantity.
• Delivered premium — the cost above the cargo benchmark for a delivered bunker.
• Ex-wharf — supply taken at the terminal rather than by barge.
• Bunker-only call — a port call made purely to stem fuel.

Regulation

• ECA — emission control area with stricter sulphur limits.
• IMO 2020 — the global 0.50% sulphur cap in force since January 2020.
• EU ETS — the emissions trading system, extended to maritime shipping.
• FuelEU Maritime — regulation targeting the greenhouse gas intensity of energy used on board.
• CII — carbon intensity indicator, an operational efficiency rating for vessels.

Operations

• Scrubber — exhaust gas cleaning system enabling compliant use of HSFO.
• Debunkering — removal of fuel from a vessel, typically after an off-spec delivery.
• Sludge — separated residue from fuel treatment.
• Barge waiting time — delay before a bunker barge can deliver, a key hub reliability metric.