At the 80th Marine Environment Protection Committee (MEPC 80), the Interim Guidance on the use of biofuels under regulations 26, 27, and 28 of MARPOL Annex VI (IMO-DCS and CII regulations) (MEPC.1/Circ.905) was approved. As a result, it is possible to calculate the CO2 emission factor (Cf) for biofuels that meet the conditions, and to use it under the IMO-DCS and CII regulations.

The following summary is the IMO Interim Guidance on the Use of Biofuels.

1. Summary of the Interim Guidance about using Biofuels

In the 2022 Guidelines on Operational Carbon Intensity Indicators and Calculation Methods (RESOLUTION MEPC.352(78) 2022 GUIDELINES ON OPERATIONAL CARBON INTENSITY INDICATORS AND THE CALCULATION METHODS (CII GUIDELINES, G1)), it is stipulated that if the type of fuel oil is not included in the relevant guidelines, the fuel supplier is required to provide the CO2 emission factor (Cf) for that type of oil, along with documentary evidence.

On the other hand, at the IMO, guidelines on Life Cycle Assessment (LCA) of greenhouse gas (GHG) emissions from the production to consumption of marine fuels (Well-to-Wake) are continually being discussed. Until the LCA guidelines are developed, it has become possible to use the interim guidance on the use of biofuels to calculate the CO2 emission factor (Cf) for biofuels that meet the following conditions, for use in IMO-DCS and CII regulations.

Conditions for biofuels that can be used in IMO-DCS and CII regulations:
(1) Certified to meet sustainability criteria through an international certification system (such as ISCC, RSB, etc.)1, and
(2) the Well-to-Wake GHG intensity of the fuel is 33gCO2e/MJ or less.

Formula for calculating the CO2 emission factor (Cf) for biofuels:
Cf [gCO2eq/g]　=　GHG Intensity [gCO2eq/MJ]　×　Lower Calorific Value (LCV) [MJ/g]

1 Refer to ICAO's Approved Sustainability Certification Scheme and the CORSIA Sustainability Criteria (Chapter 2) for CORSIA Eligible Fuels.

(To be continued)