ABS: Guidance on biofuels for Class, EU and IMO requirements

With new regulations aimed at reducing air pollutants and greenhouse gases (GHGs), there is increased interest in biofuels. Zero and low carbon fuels, such as hydrogen, ammonia, and biofuels with negligible sulfur can lower particulate matter, gaseous and carbon emissions. MARPOL Annex VI has dealt with the use of biofuels by fuel oil quality regulations under Regulation 18.3.2, while the ISO standard 8217 “Petroleum products – Fuels (class F) – Specifications of marine fuels” was modified in 2017 to widen tolerance for use of biofuels in existing and new fuel oil grades.

Class and statutory requirements

Safety – SOLAS Flash Point

Liquid biofuels, or biofuel blends, intended as “drop-in” fuels to replace conventional residual or distillate fuel oils are to meet the SOLAS requirement for a flashpoint of not less than 60° C.

Safety – ISM Requirements

The IMO International Safety Management Code (ISM Code) provides an international standard for the safe management and operation of ships and the prevention of pollution. With respect to biofuels, the fuel supplier’s fuel specifications, Bunker Delivery Note (BDN), SDS sheets, equipment manufacturer’s
recommendations and industry stakeholder guidelines provide the basis for operators to undertake their ISM Code obligations. While there are some risks to
equipment and operation with certain biofuels, the ‘drop-in’ nature and similarity to conventional residual or distillate fuels makes application relatively simple.

Environment – MARPOL Annex VI NOx Implications

IMO fuel oil quality requirements of MARPOL Annex VI regulation 18 classify fuel oils into two main categories:

1. Regulation 18.3.1.1: addresses blends of hydrocarbons from petroleum refining.
2. Regulation 18.3.2: addresses fuel oil derived by methods other than petroleum refining.

Within the latter, Regulation 18.3.2.2 indicates that such fuel is not to cause an engine to exceed the applicable NOx emission limit. Biofuels may be considered to fall under either category since they may be a blend of bioderived product with conventional petroleum derived sources or be solely bioderived. 

Guidance for operators 

Statutory NOx:

1. Operation on distillate biofuels containing up to seven percent FAME: The grades detailed by ISO 8217:2017 – is permitted and would not require NOx recertification or any onboard NOx emissions measurements to be undertaken for engines already certified to Regulation 13.
2. For blends between 7-30 percent (inclusive) biofuel: Assessment of NOx impacts is not required under the provisions of MEPC.1/Circ.795/Rev.8.
3. For blends of more than 30 percent of biofuel: If biofuel can be burnt without changes to the NOx critical components or settings, assessment of NOx impacts is also not required. Operators are to clarify whether they intend to:
   1. undertake emissions trials under MARPOL Annex VI regulation 3.2
   2. apply for use of the biofuel as an ‘Equivalent’ under Annex VI regulation 4, or
   3. apply the unified interpretation by MEPC.1/Circ.795/Rev.8.

Dialogue with the flag Administration will be required for application under regulations 3.2 or 4, and further guidance on this process can be provided by the local ABS office. Most marine 2-stroke slow speed engines and larger 4-stroke medium speed engines, which are designed for a broad range of distillate and residual marine fuels, can already accommodate a wide variation in fuel quality and have the span of NOx performance criteria associated with the engines’ adjustable features defined in the NOx Technical File. These engines are likely able to burn biofuels without any changes to the NOx critical components or settings. In these cases, confirmation from the NOx Technical File compiler or engine designer is to be obtained.

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