IMO LCA Guidelines

The IMO Guidelines on the life-cycle GHG intensity of marine fuels, adopted as Resolution MEPC.391(81) in 2024, set the method and default emission factors for assessing fuels on a well-to-wake basis. They define well-to-tank and tank-to-wake values per fuel pathway, the treatment of methane slip and N2O using AR5 100-year global warming potentials (CH4 at 28, N2O at 265), and a sustainability framework for certifying actual values. The guidelines underpin the GFI metric of the IMO Net-Zero Framework and align IMO accounting with the FuelEU well-to-wake approach.