Methane Slip

Methane slip is unburned methane that passes through a dual-fuel LNG engine and escapes in the exhaust, undermining the climate benefit of gas as a fuel because methane has an AR5 100-year global warming potential of 28. Low-pressure Otto-cycle engines slip the most, often 1.5 to 3.5 percent of fuel gas at part load, while high-pressure diesel-cycle designs slip far less. Well-to-wake accounting under FuelEU Maritime and the IMO LCA Guidelines counts the slipped methane as CO2-equivalent, which can erase the on-paper CO2 advantage of LNG over conventional fuel.