CO2 Slip

CO2 slip is a loose term for the carbon-efficiency penalty when a dual-fuel or gas engine burns its charge incompletely, so a share of the fuel carbon leaves as unburned hydrocarbons or CO rather than fully oxidized CO2 doing useful work. The dominant slip species in lean-burn LNG engines is methane, not CO2, and methane’s GWP100 of 28 makes that loss climate-relevant out of proportion to its mass. Well-to-wake accounting under FuelEU Maritime captures the full carbon-equivalent balance, so the practical effect of slip is a higher CO2-equivalent intensity than the tank-to-wake CO2 figure alone suggests.