Exhaust Gas Cleaning Systems (EGCS), commonly known as scrubbers, are used by ships as an alternative compliance mechanism to meet sulphur emission limits under MARPOL Annex VI.
Regulatory Developments and Scientific Research
During MEPC 74 (May 2019), discussions arose regarding the need for further scientific research on the environmental impacts of EGCS washwater discharges. In response, the Committee approved a new work output and requested collaboration with GESAMP to establish a task team for assessing EGCS effluent impacts.
Establishment of the GESAMP Task Team on EGCS
Following GESAMP’s 46th annual session in September 2019, a dedicated Task Team on EGCS was formed, chaired by Mr. Jan Linders (GESAMP Member) and comprising eight experts in:
- Fluid dynamics & modelling
- Marine chemistry
- Ecotoxicology
- Human toxicology
- Risk assessment
- Environmental marine biogeochemistry
The Task Team convened from 29 October to 1 November 2019 and submitted its findings in PPR 7/INF.23 to the Sub-Committee on Pollution Prevention and Response (PPR 7, February 2020).
Key Outcomes and Guidelines
The GESAMP Task Team’s recommendations were reviewed in subsequent PPR and MEPC sessions, culminating in the adoption of the 2022 Guidelines for Risk and Impact Assessments of EGCS Discharge Water (MEPC.1/Circ.899) at MEPC 78 (June 2022).
These guidelines recommend using unified and representative Emission Factors (mg/MWh) based on data collected by the IMO. However, discussions on emission factors remain ongoing due to:
- Differing methodologies for determining emission factors
- Discrepancies in proposed values
- Questions regarding data quality and handling of non-detects
Next Steps: Re-establishment of the GESAMP Task Team
To address these challenges, proposals were submitted to MEPC 83 for the re-establishment of the GESAMP Task Team on EGCS. The team’s renewed mandate will focus on:
- Developing representative emission factors
- Enhancing environmental risk assessment of EGCS discharge water
- Providing progress updates and recommendations to PPR 13 (9-13 February 2026)
This ongoing work ensures that EGCS regulations remain scientifically robust while balancing environmental protection and maritime industry needs.