From Truck to Rail to Ship

It seems to me that the environmental agenda evolves from what is closest to us then moves to the more remote. In the case of diesel engines, it started with truck engines, then progressed to locomotive engines and now marine engines come under scrutiny.

Automotive diesel engines burn very clean fuel today, with S-content of not more than 50ppm, or 0.005% S-content by mass; therefore emit only small amounts of SOx and particulate matter. Regulations now require also the installation of secondary exhaust gas treatment (SCRs) and particulate filters on trucks and cars; to eliminate NOx and PM.

Locomotive engines are somewhat bigger than truck engines and with size some basic mechanical requirements need to be satisfied. The fuel pumps and the diesel injectors are bigger than what we see in trucks, therefore sliding surfaces become bigger and the lubricating oil film the fuel provides becomes more difficult to maintain as the fuel becomes lighter and less viscous. Installation of exhaust gas after treatment on locomotives becomes an issue because of size and suitability for the fuel used. The question is, can locomotives be made as clean as trucks, when it comes to exhaust emissions?

Stepping then up in size again to the large bore marine engines the problem gets bigger. The lubrication provided by the fuel in the injection equipment increases in importance because these components are massive.

What I hear from the experts is that diesel engines up to 250mm bore should operate with a fuel viscosity of at least 1.8cSt at the fuel injection pump, above that bore 2.0cSt or higher is recommended. These viscosity values mean that for the safe operation on a ship fuel temperature needs to be maintained and cooling or chilling of the distillate fuel may become necessary to maintain the lubricating properties of the fuel. As it stands now, it seems that ULS road diesel can not be safely burnt in the large bore marine engines.