Fuel for the future

LNG as a fuel for ships has a lot of attractions, but is far from being the only answer. Although It undoubtedly offers considerable reduction in NOx, SOx and PM emissions, and a further reduction in CO₂, it brings its own drawbacks, in such things as the volume required for onboard storage, the current lack of refuelling infrastructure, and the not-insignificant problem of methane slip – which could negate many of the greenhouse gas savings. Nevertheless, it is being taken seriously as a fuel for ship types that previously would have no more used gas fuel than sail to the moon.

There are of course other alternative fuels, and methods of propulsion, to be considered. There is definitely a place for renewables, e.g. wind power and solar power (or, more accurately photovoltaic cells), albeit as supplementary power rather than prime movers. Bio-fuels are a further possibility, though what could possibly provide a source of sufficient bio-fuel to power the world fleet is not known – a vast amount of organic waste, or millions of hectares of agricultural land to produce the plant material would seem to be needed. Though emerging economies like Brazil claim to offer some of the bio-fuel answers. And fuel cells have a long way to go, but the promise is definitely there.

Perhaps one of the strongest possibilities is radical improvement of the internal combustion engine. Although current ship propulsion units work wonders in producing large amounts of power from what is, in effect, a waste material (i.e. heavy fuel oil), the Diesel engine is relatively low in the scale of machine efficiency. Novel combustion technology looks encouraging; several small innovators are involved, among them Ultramo, featured in this (Septemmber 2011) issue, and Kaz Technologies, whose proposals were presented at the recent Motorship Propulsion & Emissions Conference. The Kaz Technologies gun engine combines Diesel principles with the firing of a gun – a second piston represents the ‘bullet’ – and so captures increased energy from a given amount of fuel. It’s a novel approach, and one that brings its own problems, like any new development, but it shows promise, and we hope to explore it in more detail in these pages soon.