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Increasing LNG benefits by decreasing methane slip

Does the issue of methane slip affect the climate-benefits of LNG as an engine fuel for marine applications? MAN Energy Solutions remains convinced that the switch to LNG marks an important first step towards climate-neutral shipping and has prioritized the resolution of methane slip accordingly.

Addressing methane slip

Used as a shipping fuel LNG offers various benefits both for ship owners and the environment. With its high heating value combined with low carbon content, LNG enables a significant reduction in emissions of greenhouse gases (GHG), while an absence of sulphur content also lowers reductions in emissions of particulate matter (PM) and oxides of sulphur (SOx) – and all that comes at lower fuel costs.

Lately questions have been raised regarding the climate risks associated with methane slip. The term means the emission of small but significant quantities of unburnt methane (CH4) into the atmosphere. This is an issue that needs close observation, as methane is a greenhouse gas considerably more potent than carbon dioxide (CO2).

LNG-carrier
20
%
potential reductions in CO2 by using LNG
0,25
g/kWh
negligible methane-slip of MAN’s ME-GI two-stroke DF engines at 50 % load
50
%
reduction of methane slip from the four-stroke MAN 51/60 DF engine during last 10 years

Taking up the challenge

We are determined to resolve the issue of methane slip. For our two-stroke engines, we are already offering technical solutions to minimize methane slip. Employing the diesel combustion principle our ME-GI two-stroke dual-fuel engines guarantee negligible methane slip levels in a range from 0.2 - 0.3 g/kWh over the engines’ load range.

For our four-stroke dual-fuel (DF) engines, we are energetically pursuing such solutions. In our range of four-stroke gas-burning engines employing the Otto combustion process, we have already halved methane slip over the past ten years to a level where the combined GHG impact of CO2 and CH4 is today notably below the respective figure for liquid burning diesel engines. Our technical department is energetically pursuing several routes to further minimize methane-slip from four-stroke gas-burning engines in the next years.

We are confident that methane slip will not become a barrier to either the expansion of the market for gas-burning engines or the progression of the Maritime Energy Transition.

Download Technical Paper