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 
5 Legal framework 
Sulphur oxide emissions from sea-going ships are regulated in Regulation 14 of the revised 
MARPOL Annex VI by specifying a progressive reduction on the sulphur content in fuels used on 
board. Regulation 14.1 set the limit values worldwide for fuels sulphur content; since 1 January 
2020 the global limit is 0.5% m/m, known as the Global Sulphur Cap 2020. Regulation 14.4 set 
even lower limit values in designated special areas (ECAs - Emission Control Areas); since 1 
January 2015 the ECA limit is 0.1% m/m (MEPC, 2008c). The Baltic Sea, North Sea, American 
Caribbean Sea and North America are currently defined as sulphur ECAs (IMO, 2020). 
At the same time, Regulation 4.1 of MARPOL Annex VI (MEPC, 2008c) allows for “any fitting, 
material, appliance or apparatus to be fitted in a ship or other procedures, alternative fuel oils, or 
compliance methods used as an alternative to that required by this Annex if such (...) are at least as 
effective in terms of emissions reductions as that required by this Annex, including any of the 
standards set forth in regulations 13 and 14“. EGCS are recognized as an equivalent compliance 
method according to Regulation 4 of MARPOL Annex VI, capable of fulfilling the aforementioned 
standards of Regulation 14 while still allowing for the use of non-compliant fuel. 
Regulation 14 of MARPOL Annex VI is basically a measure to control sulphur emissions by 
establishing fuel quality standards. By using compliant fuel, the formation of SOx is prevented 
(to a certain extent), addressing the source of the problem. By use of EGCS (allowed by 
Regulation 4 of Annex VI), the formation of SOx is not avoided. Instead, the formed SOx are 
transferred from the exhaust gas to washwater. Depending on the type of EGCS, different waste 
streams are generated, which might contain pollutants of concern that end up in the marine 
environment by direct discharge to water bodies (see chapter 2). 
For ships using EGCS (and non-compliant fuel), Regulation 14 of MARPOL Annex VI cannot be 
monitored directly (by fuel sulphur content analysis). Instead, SOx and CO; emissions in exhaust 
gas must be measured and using the emission ratio SO2 (ppm)/CO; (%v/v) can be indirectly 
compared to the limits set in Regulation 14. Apart from this, due to the occurrence of EGCS 
discharge water and other waste streams, additional regulations are required to control their 
discharge and disposal. In other words, both emission streams to the air and to water bodies are 
of concern and regulated in several laws and directives. This chapter recapitulates briefly some 
international, European and national German regulations that apply to the control of EGCS 
discharge water. 
5.1 International regulations for EGCS discharge water 
The 1982 United Nations Convention on the Law of the Sea (UNCLOS) contains in Part XII 
(Articles 192-237) the fundamental international provisions for protection and preservation of 
the marine environment. The General Provisions (Articles 192-196) shall be regarded for the 
acceptance of discharge of EGCS discharge water (Proelß and Schatz, 2019). Of particular 
relevance is Article 195 specifying: “In taking measures to prevent, reduce and control pollution of 
the marine environment, States shall act so as not to transfer, directly or indirectly, damage or 
hazards from one area to another or transform one type of pollution into another”. 
The water and waste discharges from EGCS are predominantly addressed at international level 
by MARPOL Annex VI and its linked guidelines. The 531 session of the MEPC developed the 
guidelines for EGCS (Resolution MEPC.130(53), MEPC (2005)) that included the requirements 
for the design, testing, survey and certification of EGCS. These guidelines were last updated in 
2015 (Resolution MEPC.259(68), commonly known as “2015 EGCS Guidelines”, MEPC (2015)). 
Although these guidelines are not legally binding, administrations of the contracting Member