LNG as a marine fuel: How green is it?

Many thanks to James M. Turner QC for this guest blog on LNG

LNG has been used as a fuel in gas carriers for decades, with ships carrying LNG using some of the boil-off gas to supplement conventional bunkers.  Over the past decade, with environmental concerns mounting, LNG has also entered the bunkering mainstream, with many ships now being built that are capable of being run on LNG or normal fuels.  Part of the draw of LNG is that its carbon content is much lower than that of fuel oil or gas oil, and the associated CO2 emissions are correspondingly much reduced.

So far so good.  Unfortunately, however, LNG consists in large part of methane.  As we have all come to understand - see for example the environmental overhead of beef farming - methane is an even more potent global warmer than CO2.  That’s fine if you burn it, but not if it escapes before burning.  The most popular implementation of LNG engines on ships does not score well on this.  Indeed, research suggests that, over a 20-year period (the typical lifetime of a ship), the greenhouse gas emissions from LNG-burning ships’ engines are significantly worse than from an engine burning marine gas oil.

It is unfortunate that the principal focus in recent times has been on particular types of emission (principally SOx and NOx) and CO2, on all of which LNG scores well.  The coming years will see an adjustment, one hopes, to concentrate on the overall effect of a particular fuel, in order to identify one that both shipping and the planet can live with.  The current favourite is ammonia, but the technology required to make ammonia commercially viable and environmentally sustainable is still in development.  Watch this space.

James is a member of Quadrant Chambers where he specialises in cross-border commercial disputes in international arbitration, energy, shipbuilding, offshore construction, shipping and banking.