Whiff of sulphur

Just as the whiff of vapour rising from oiled beaches started to drift away on the wind, or at least showed signs of being contained inside the double-hulls of the next generation of tankers, another bad smell has started to waft over shippers. Sulphur, that devil’s fire-and-brimstone favourite, is in the air and threatens to become more than a tang in shipowners’ nostrils.

Last week, the USA took a giant step towards ratifying Marpol annex VI, which should ultimately create an international standard for the control of marine air emissions. Panama is thought to be close to ratification, as are several member states of the European Union. If several more states jump on board, then the measure could take effect from 2005.

But how will emissions cuts actually be achieved? The European Union’s preferred solution is to slash sulphur emissions at a stroke by demanding that ships operation in EU waters burn fuel with no more than 1.5 per cent sulphur, or 0.2 per cent in port.

But, while that solution may be effective and easily enforced by environmental protection agencies, ships may find have to carry, in segregated bunkers, two or three grades of fuel. They could, of course, run on 0.2 per cent fuel the whole time, but the two low-sulphur grades would be some $20-50 per ton more expensive than dirtier fuel, and may well be hard to find outside of Europe.

The issues associated with the fuel level cap option have been most loudly raised by fuel companies. ExxonMobil says there are no problems switching from high- to low-sulphur fuel of the same viscosity, but in changing from fuel oil to gas oil there are risks, including the loss of engine power. Lubmarine notes cylinder lubrication oil is formulated on assumptions of acidity, so occasional use of low-sulphur fuels could lead to excessive alkalinity and piston crown deposits.

Shell Marine marketing controller Graham Wylie says suppliers and shipowners would do better in a scheme to control emissions by encouraging the use of “complementary technologies” on board ship. One system with promise is the Eco Silencer sulphur scrubber, which uses seawater to tackle sulphur in exhaust and is currently being trialled by BP and P&O Ferries in the English Channel.

Wylie says Shell also holds out hope for a workable emissions trading system, and BP has also pushed for this approach. Under such a scheme, ships operating exclusively or mostly in EU waters would be encouraged to cut sulphur emissions below legal limits, earning emissions credits they could sell to ships passing through the EU.

Says Wylie, land-based power generators have had some success with CO2 trading, and evidence suggests that the overall effect on air quality could be better than with a simple fuel content cap.

However, he adds, such system could only work with an effective system of emissions measuring and compliance monitoring. The shipping industry had better, then, pull together and quickly develop a groundbreaking proposal or risk finding out how tough the EU can be on polluters.