WHATEVER your view on liquefied natural gas, it will be part of shipping’s fuel mix for years to come.

So yesterday’s news that three Japanese firms — MOL, Kanadevia Corp and Yanmar Power Solutions — have reduced methane slip from a coal carrier by up to 98% is certainly welcome.

For the planet’s sake, engine makers and tech firms must work out how to eliminate leaks of unburned methane from gas ships’ exhaust plumes.

Such leaks have an outsized climate impact, since a tonne of methane in the atmosphere warms the planet 80 times more than a tonne of CO2 over 20 years.

The latest high-pressure, two-stroke LNG engines slip virtually no methane — or so their builders claim. But leaky, low-pressure Otto-cycle engines still dominate the market, especially four-stroke engines. At 3.5% methane slip, LNG is little better than VLSFO.

Measuring real-world methane slip is no mean feat, and we must know more about its causes and prevention.

MOL used oxidation catalysts to strip methane from the ship’s exhaust, as well as recirculating that exhaust through the engine. The 98% reduction was achieved at 75% engine load. How well the catalyst works when the engine isn’t working as hard was not mentioned.

The new tech’s cost, effectiveness and reliability won’t just be important for gas ships. Ammonia engine makers will also have to prevent leaks of unburned ammonia (which is highly toxic) and nitrous oxide (N2O, which is 300 times stronger than CO2).

The industry insists it is fixing the problem of methane slip. Regulators must hold it to that — with strict monitoring, tough controls and real incentives.

Declan Bush
Senior reporter, Lloyd’s List