Liquid natural gas (lng) could well become shipping’s dominant fuel within the next ten years, according to the head of DNV, Henrik Madsen, who revealed the results of the class society’s latest innovation project to journalists in London this week. DNV’s concept, Triality VLCC – powered by lng – is one of the first examples of an ocean-going merchant vessel fuelled by gas. Madsen believes the first such vessels could be ordered as soon as 2012 and delivered to owners some time in 2014.

Whilst most major class societies are vigorously pursuing new technologies to improve shipping’s overall fuel consumption and emissions profile, DNV is spearheading the dash for gas propulsion which has already produced a series of gas-powered coastal craft, notably ferries working on the Norwegian coast, as well as offshore support vessels operating in the North Sea. Until now, convenience and availability of the fuel have been held up as obstacles by those resisting the developing technology. But already this is changing, with bunkering facilities available at various locations in Norway, as well as the development of other gas-bunkering facilities in the Baltic.

Madsen points out that although the availability of natural gas has been limited to some extent until now, gas is increasingly widely available in various locations, notably those which dominate global VLCC trades, including the Middle East, the Far East, Europe and the US. And in any case, he says, the new DNV concept design – already discussed in outline with three major shipbuilding groups – envisages that the new VLCC will have sufficient fuel capacity on board, with lng stored in two 6,750 cubic metre tanks on deck, forward of the bridge, to enable the vessel to circumnavigate the globe, if required to do so. Marine gas oil will be used as a pilot fuel.

He also highlights two other significiant developments which could prove to be important catalysts in the development of gas propulsion. Firstly, he refers to the new 200 nautical mile Emissions Control Area around the north American coast, requiring the owners of ships trading there to burn increasingly costly low-sulphur fuels. And secondly, he says, lng is already significantly cheaper than heavy fuel oil and, as more reserves come on stream in due course, the differential is likely to widen. Moreover, the pace at which this occurs could well quicken, as the price of low-sulphur fuel escalates.

As in the class society’s Quantum container ship concept, unveiled last year, the 30-odd DNV staff working on the Triality VLCC concept have certainly thought hard about ways in which operating efficiency can be improved and the VLCC incoporates a range of exciting new features. These will result in a higher first cost of 10-15% but should provide a net benefit over a 20-year operating life, according to DNV. In fact, according to Project Manager Torill Grimstad Osberg, based on a discount rate of 8% and a 20-year life, there is a net present value benefit of some $24m.

Of course, lng as a principal fuel source has a dramatic effect on ship emissions and, according to DNV, the Triality VLCC will emit 34% less carbon dioxide, 80% less NOx and 95% less SOx and particulates. Significantly, though, no cargo vapours will be vented from the vessel, with VOCs condensed and used as a fuel to run auxiliary boilers producing steam for cargo pumps. The ship’s generators are dual fuel – lng and marine gas oil.

However, perhaps the most radical departure from conventional VLCC designs – apart from the main propulsion system – is the fact that the Triality VLCC will not need to carry any ballast. New loading and discharging procedures will eliminate the need to pump ballast during cargo operations whilst the V-shaped hull will mean a significantly reduced wetted surface area when not carrying cargo, thereby minimising hull resistance. Not carrying a typical ballast load of 100,000 tonnes will also clearly improve fuel economy and altogether, DNV estimates that its Triality VLCC will use some 25% less energy than a conventional VLCC.

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