Certification of exhaust gas cleaning systems for maritime applications

Recent developments of extremely high levels of engine efficiency combined with the use of cheap, low-quality fuels has resulted in significantly increased emissions of nitrogen oxides (NOx), sulphur oxides (SOx) and particulate matter. Consequently the International Maritime Organisation (IMO) and various national and local administrations have reacted by establishing policies to prevent and control air pollution from ships leading to a challenging task in understanding all legal and administrative requests. In the Revision of MARPOL Annex VI dated 2008 the International Maritime Organisation agreed to further tighten the limits on the emissions of nitrogen oxides. In the second stage (Tier II) a reduction in nitrogen oxide emissions by about 20% compared to the previous values is required. The third stage of emission limits for nitrogen oxides (Tier III) shall apply to new buildings with keel laying from 1 January 2016 when navigating Emission Control Areas (ECAs). In particular, this third stage imposes a strong challenge for engine manufacturers, ship operators and certifiers (Recognised Organisations / classification societies) from a technical and operational point of view. As without specific treatment of the exhaust gases the third level of emission limits for nitrogen oxides is unlikely to be met. For this reason the International Maritime Organization recently published guidelines for the use of after-treatment systems. The correct executions of the guidelines have to be proven and guaranteed from the perspective of a classification society. Moreover the installation and operation of such systems must be both: in compliance with these guidelines and in conformity with a safe ship operation. To this end, Germanischer Lloyd has extended its rules to a section on exhaust gas aftertreatment systems. In this work latest updates and future emission standards for marine applications are introduced. The purpose of this work is to show technical solutions for exhaust gas aftertreatment systems from the perspective of a classification society with a strong focus on its technical, operational, organizational and administrative challenges.