TEXTE Environmental Impacts of Exhaust Gas Cleaning Systems for Reduction of SOx on Ships — Analysis of status quo 
Report compiled within the framework of the project ImpEx 
1 Introduction 
In order to reduce sulphur oxides (SOx) and particulate matter emissions from sea-going ships, 
cegulation 14 of Annex VI of the International Convention for the Prevention of Pollution of 
Ships (MARPOL) sets out sulphur limits in fuel oil used on board ships. As an alternative, EGCS 
‘commonly referred to as “scrubber”) may be operated on board to reach at least equivalent SOx 
emission reductions, while still using non-compliant fuels, as allowed under regulation 4 of 
MARPOL Annex VI. The implementation of the sulphur limit in Emission Control Areas (ECAs) 
(0.1%) in 2015 and, more recently, of the global sulphur limit (0.5%) in 2020 has boosted the 
development of the market of EGCS in the maritime sector. 
Before the entry into force of MARPOL Annex VI in 2005, the use of EGCS on board ships as an 
equivalent method for the compliance with Regulation 14 has been discussed at the MEPC and 
other subcommittees of the IMO. Environmental concerns regarding the release of EGCS 
discharge water have been a subject of discussion. In section 10 of the Guidelines for Exhaust 
Gas Cleaning Systems (EGCS Guidelines) discharge criteria have been defined generally intended 
to prevent acute effects occurring in the aquatic environment (GESAMP, 2009). Since the EGCS 
Guidelines of 2008, it has been noted that the discharge “criteria should be revised in the future as 
more data becomes available on the contents of the discharge and its effects, taking into account 
any advice given by GESAMP” (MEPC, 2008a; MEPC, 2009; MEPC, 2015). Attending the need to 
generate information about the EGCS discharge water, the German Federal Maritime and 
Aydrographic Agency (BSH) carried out on behalf of the German Environment Agency (UBA) a 
oroject (2016-2019) that included a sampling campaign on board five vessels equipped with 
EGCS, chemical characterization of water samples as well as an emission and distribution 
modelling of EGCS discharge water in the Baltic Sea and North Sea. The project report concluded 
that further research is needed for a better quantification and evaluation of the total impact on 
the marine environment of this abatement technology (Schmolke et al., 2020). Concerning that 
matter and to address specific questions arisen from the mentioned project, a follow-up project 
(ImpEx - Environmental Impacts of Exhaust Gas Cleaning Systems for Reduction of SOx on Ships, 
2020-2023) is conducted on behalf of UBA by a consortium of German federal agencies, state 
authorities and institutions. The project ImpEx shall contribute to a factual discussion on the 
concerns from EGCS discharge water in marine environment. The here presented results of WP 
1 of the project include an overall review on the status quo of EGCS, with special focus on the 
environmental aspects of the discharge water. It is based on a literature review and covers 
technical aspects, market analyses, the regulatory framework and recent research activities 
related to this topic. Further information about the project is presented in Table 6. 
16