Sulphur free fuels

Some bulk trades, such as Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG), are carrying as cargo fuels that are free of sulphur.

The economics will vary according to the specific trade, and it may be appropriate to use the cargo as fuel, so achieving very low emissions of sulphur.

Engines using LNG or CNG need complex modifications to change from normal fuel oils, and it is hard to make such vessels able to use both fuels efficiently.

The key complexity is the need to vary the engine compression ratio.