May 14, 2003
Fuel sulfur cap proposals pose hazards
Steve Walker, Global Technical Manager of EMMF, told the recent International Bunker Conference in Rotterdam that, while any move to ensure cleaner air should be welcomed, the current EC proposal for amendment of the EU directive on sulfur in liquid fuels has yet to look in depth at the real effect it will have on the end-user.
Walker explained that, for internationally trading vessels, the current proposal would involve having three grades of fuel--4.5 percent sulfur bunker fuel, 1.5 percent sulfur bunker fuel, and 0.2 percent sulfur gas oil--in terminals and on board ships.
Changing from high-sulfur to low-sulfur fuel oil of the same viscosity was not a problem, said Walker. But changing from fuel oil to gas oil raised a number of potential difficulties. These included thermal shock of fuel system components, and a loss of power and maneuverability as a result of the system gassing-up.
"How long will it be after implementation of the legislation," he asked, "before the root cause of a casualty is noted as loss of main engine power caused by gassing-up of the vessel's fuel oil system?"
Walker added, "Of more concern is the potential safety issue of changing over boiler plant from fuel oil to gas oil firing. Many tankers have boilers to drive their cargo plant, and many LNG carriers use boilers to drive steam turbine propulsion systems. Under the proposed legislation, these vessels would have to fire their boilers on 0.2 per cent sulfur fuel whilst alongside in Europe.
"Introducing diesel into a hot furnace could be dangerous if extreme care is not taken to ensure that the boiler furnace is correctly purged of all gases. Even then, if the fuel does not light off immediately, it will vaporize and could result in a furnace explosion and catastrophic failure of the boiler itself."
Noting also that the question of segregating and carrying three grades of fuels raised serious difficulties for shipowners, Walker concluded that alternatives to a pure sulfur cap needed to be explored. He said initial findings suggested that new-generation exhaust gas scrubbers, although significant in terms of capital outlay, could achieve major reductions in emissions levels while also addressing NOx emissions, provided it is demonstrated that sea water scrubbing is acceptable with respect to sea water pollution.
And he said, "It is not all doom and gloom. Engines using low-sulfur fuel on a permanent basis will be able to use lube oils with a lower TBN additive package and, as a result, may be less expensive. Engine components should last longer, and fuel-testing agencies are likely to benefit from a boom in work. And, above all, if the legislation works, we will all have cleaner air to breathe."