Global scrubber washwater discharges under IMO’s 2020 fuel sulfur limit

More and more, to comply with the International Maritime Organization’s (IMO) 2020 global fuel sulfur limit, ships are using scrubbers (exhaust gas cleaning systems). Scrubbers remove sulfur from ship exhaust by spraying it with seawater and dumping the untreated washwater overboard. Washwater is more acidic than seawater and contains polycyclic aromatic hydrocarbons, particulates, nitrates, nitrites, and heavy metals. Such washwater is toxic to marine organisms and can degrade seawater quality. The authors have performed the first assessment of washwater discharges anticipated worldwide. The authors used 2019 ship traffic statistics as a baseline, and studied about 3,600 ships equipped with scrubbers. The results show that ships with scrubbers will emit at least 10 gigatonnes (Gt) of washwater annually. (To put this in context, the entire shipping sector annually carries about 11 Gt of cargo.) Because the authors’ estimates for washwater discharges were cautious, and the scrubber-equipped fleet now stands at more than 4,300 vessels, actual discharges could well be higher. About 80% of washwater discharges occur within 200 nautical miles of shorelines, and are notable in regions with heavy traffic, including the Baltic Sea, North Sea, Mediterranean Sea, the Strait of Malacca, and the Caribbean Sea. Discharges also occur in IMO-designated Particularly Sensitive Sea Areas (PSSAs), including the Great Barrier Reef, where about 32 million tonnes (Mt) of washwater is expected annually. This figure represents just 5% of the 665 Mt expected discharges in PSSAs around the world. Some governments have banned scrubber usage in ports, inland waters, and territorial seas, while many have not. Concerned policymakers should consider several actions: The IMO could call on ships to cease from dumping washwater in PSSAs, and prohibit the use of scrubbers by requiring that ships use cleaner fuels. Countries and ports could ban discharges in their waters, and states could agree to phase out scrubbers on ships using their flag.

• Record URL:
  https://theicct.org/sites/default/files/publications/scrubber-discharges-Apr2021.pdf
• 
• Summary URL:
  https://theicct.org/publications/global-scrubber-discharges-Apr2021?utm_source=ICCT+mailing+list&utm_campaign=80679151aa-lately_from_feb2018_COPY_01&utm_medium=email&utm_term=0_ef73e76009-80679151aa-451744717
• Supplemental Notes:
  • An interactive map showing the distribution of scrubber washwater discharges can be accessed at this link: https://theicct.org/publications/globalscrubber-discharges-Apr2021. A spreadsheet summarizing the amount of scrubber washwater discharges within each country’s Exclusive Economic Zone, territorial seas, internal waters, major ports, and from ships that fly each country’s flag can is available at the web page for this report: https://theicct.org/publications/global-scrubber-discharges-Apr2021
• Corporate Authors:

  International Council on Clean Transportation (ICCT)

  1500 K Street NW, Suite 650
  Washington, DC  United States  20005
• Authors:
  • Osipova, Liudmila
  • Georgeff, Elise
  • Comer, Bryan
• Publication Date: 2021-4

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; Maps; References; Tables;
• Pagination: 32p

Subject/Index Terms

• TRT Terms: Desulfurization; Exhaust gases; Ocean shipping; Scrubbers; Seawater; Ships; Washing; Water pollution
• Subject Areas: Environment; Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 01777016
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 23 2021 3:23PM