There is no doubt that the international shipping industry contributes a measurable share of greenhouse gas and pollutant emissions both on the world's oceans and inland. Most of their propulsion engines burn fuels with a high sulphur content and an overall low level of purity. This problem has been recognized and the transformation of ship propulsion systems has been initiated worldwide. Correspondingly stricter emission limits have been set and are gradually taking effect (International Maritime Organization - IMO defines the environmental protection requirements for maritime shipping in the "International Convention for the Prevention of Pollution from Ships" (MARPOL Convention)).