Green credentials have potential

Over the next few years shipowners could find themselves having to contend with a patchwork of environmental legislation.

Shipowners are accustomed to their existing fleet escaping the vast majority of new legislation — but things are changing. Sweden’s environmentally differentiated port and fairway schemes affect all vessels, not just newbuildings. Norway, Denmark, Germany, and possibly the whole of EU are likely to introduce similar schemes over the next few years, making it more expensive for vessels emitting more pollution to visit a port.

Therefore it could be in owners’ interests to look at options for reducing NOx on existing vessels, and certainly to plan such measures into their newbuildings. Investment of $40-$70/kW is needed to install a SCR to get the maximum discount on offer by the Swedish Authorities,but other measures are cheaper, although the emission reductions are lower. If other countries follow Sweden’s lead in introducing a sliding NOx scale (12 g/kWh down to 2 g/kWh), even small reductions could give a good payback.

Norway’s NOxRED scheme is aimed at reducing NOx emissions from its coastal fleet, and its Maritime Directorate is funding research into strategies to cut emissions from existing vessels. Shipowner Bergesen is participating in one of the experiments using emulsified fuel in a Sulzer RTA84M engine. Two homogenisers have been installed on the vessel — one between the settling tank and the separator, and one in the booster system itself. Fleet manager Mr O E Toft, says because of the fuel pump capacity, at full load only about 10 per cent of water can be added, while at lighter loads he feels up to 20 per cent is feasible.

Marcus Geist, two-stroke production manager, Wartsila NSD, says that the capacity available for water inclusion depends on the amount of power operators wants to use. If they are happy to limit the engine to 85 per cent MCR then there is capacity for up to 30 per cent water. However, if they want the full 110 per cent, as delivered by the builder, available for emergencies then there is only room for about 10 per cent water.

Peter Sunn Pedersen, vice president of R&D, says at full load new MAN B&W fuel pumps have about 30 per cent excess capacity to account for leakage as the pumps wear. He points out that adding water to the fuel will increase its volume and viscosity, requiring a higher pre-heat temperature to reach the specified viscosity. The extra volume will increase the load on the camshaft drive and change the injection duration setting of the starting index on the governor, says Mr Sunn Pedersen.