Answer
FAME is Fatty Acid Methyl Ester, a biodiesel produced from renewable oils or fats. IMO permits its use as marine fuel, but MARPOL Annex VI still applies. Under the IMO Unified Interpretation of Regulation 18.3, blends up to 30% biofuel are dealt with under Reg. 18.3.1, while blends above 30% come under Reg. 18.3.2. The engine must continue to comply with its certified NOx limits, and BDN, sampling and fuel-quality requirements are applicable.
Fatty Acid Methyl Esters (FAME): FAME is produced via transesterification of renewable feedstocks like vegetable oils, used cooking oil (UCO), and animal fats with methanol. It can be used neat or blended with conventional marine diesel fuel, e.g. B20 = 20% FAME + 80% fossil fuel.
Concern with FAMERemember “FAME = good for carbon, challenging for storage.”
Main practical concerns are oxidation, water absorption, microbial growth, poor cold-flow characteristics, deposit/filter blockage, compatibility with seals/materials, and shorter storage stability. Therefore, before using higher FAME blends, check engine-maker approval, ISO fuel specification/analysis, tank cleanliness, fuel compatibility and PMS requirements.
FAME being renewable does not automatically mean zero-carbon fuel. IMO GHG accounting increasingly considers its life-cycle/WtW emissions and sustainability of the feedstock, not simply the CO₂ emitted at the engine.
Relation of FAME with IMO standards
| IMO requirement | Relation with FAME |
|---|---|
| MARPOL Annex VI Reg. 18 – Fuel oil quality | FAME/biofuel used onboard must comply with fuel-quality requirements. IMO recognizes FAME as a biofuel. |
| ≤30% biofuel blend | IMO Unified Interpretation treats a blend containing not more than 30% biofuel by volume under Reg. 18.3.1. |
| >30% biofuel blend / neat FAME | Falls under Reg. 18.3.2, because its composition is substantially different from conventional petroleum-derived fuel. |
| MARPOL Annex VI Reg. 14 – SOx | FAME normally contains very little sulphur, so it can readily help meet the 0.50% global sulphur limit and 0.10% ECA limit. |
| MARPOL Annex VI Reg. 13 – NOx | The engine must still comply with its applicable Tier I/II/III NOx limit and EIAPP/NOx Technical File requirements. Fuel change must not invalidate engine certification. |
| CII / GHG reduction | FAME may reduce lifecycle GHG intensity compared with fossil fuel, depending on its feedstock and lifecycle pathway. It is therefore relevant to IMO decarbonization measures. |
| BDN and sampling | Biofuel bunkers remain subject to applicable Bunker Delivery Note, representative sampling and fuel-quality documentation requirements under Annex VI. |