Well-to-wake

Well-to-wake is the full life-cycle emissions boundary for a marine fuel, summing upstream well-to-tank emissions (extraction, production, and transport of the fuel) and onboard tank-to-wake emissions (combustion and any fugitive slip). It is the accounting basis of FuelEU Maritime and the proposed IMO GFI, and it is the boundary that exposes fuels with low onboard CO2 but high upstream carbon, such as grey hydrogen or fossil LNG with methane slip. The IMO LCA Guidelines (MEPC.391(81)) set the default well-to-tank and tank-to-wake factors per fuel pathway.