What the measurement leads to
MEPC.414(84) does not stop at the measurement. The applicant prepares a CH4 and/or N2O file, and the file is submitted to the Administration for verification. After satisfactory verification, the Administration issues a Statement of emission values for CH4 and/or N2O.
The measurement is therefore planned from the start with the file in mind. Data that was not recorded during the test is hard to add afterwards.
What goes into the file
The guidelines list what the file should contain: the details of the engine as tested, including model, rated power and speed, the components and settings that affect CH4 and N2O, and for methane the maximum liquid-to-gas fuel ratios across the load range. It also holds drawings of the exhaust system showing the sampling positions, and a copy of the engine test data with the data needed to calculate the emissions.
Where methane slip is reported, crankcase emissions are included only for trunk piston engines without closed crankcase ventilation. If a methane reducing device is fitted, the file also documents its purpose, how it works, its critical components, settings and consumables.
One file, also for the EU
The European Commission has published guidelines for reporting and verifying actual methane slip under FuelEU Maritime. They are not legally binding. They ask the company to prepare the Methane File as required by the earlier IMO guidelines, MEPC.402(83), which MEPC.414(84) replaces, complemented with some additional information, such as allowable ranges for settings and the influence of ambient conditions.
The Methane File is approved by the flag administration or an organisation recognised by it. It is then referenced in the FuelEU Monitoring Plan, and the FuelEU verifier checks it together with Engine Load Monitoring of how the engine is loaded in service. The verifier verifies the shipping company, not ME-Tech. Use in EU MRV and ETS reporting should be agreed with your verifier.
The route in short
One measurement and one file can serve both the IMO guidelines and FuelEU Maritime, if the measurement is planned for both. The steps below show the route.
Where we come in
We plan and carry out the measurement and prepare the measurement data and documentation for the file, in close collaboration with the engine designer, the owner and class. Other steps, such as load logging, are separate tasks that can be added as an extra.
What we recommend
Agree with the Administration what the file must contain before the measurement, so the data is recorded during the test. Agree the use of the file with your FuelEU verifier before you rely on it.
IMO resolution MEPC.414(84), sections 2 and 4 and appendix 3; European Commission, guidelines for reporting and verification of actual methane slip (October 2025); Regulation (EU) 2023/1805 (FuelEU Maritime).
