As of 1 January 2020, Annex VI reduced the allowable sulphur content in marine fuel from 3.5 percent to 0.5 percent. This will yield significant global health and environmental benefits, especially in coastal areas and port cities, by reducing the amount of sulphur emissions to air when fuel is burnt.
Ships can meet the sulphur fuel limit by using either compliant (low-sulphur) fuel, or through the use of an equivalent technology that achieves at least the same reductions in sulphur emissions to air, such as an exhaust gas cleaning system (scrubber).
Scrubbers systems use either seawater or modified freshwater to remove gases and other combustion products from the ship’s exhaust. Scrubbers can discharge a diluted washwater (‘open loop’ systems) or in some cases a more concentrated ‘bleed off’ (‘closed loop’ systems). Both are discharged to the marine environment. Some ships carry hybrid scrubber systems which can operate in both open and closed loop mode. These discharges contain a number of contaminants such as heavy metals. The amount of discharge and the concentration of contaminants will vary.
There are some concerns around the potential risks these contaminants pose to the marine environment. To better understand the risks of scrubber use in New Zealand waters, the Ministry for the Environment engaged the National Institute of Water and Atmospheric research (NIWA) to carry out a preliminary risk assessment on scrubber discharges. This research also considered te ao Māori perspectives reflected in publicly available Iwi Environmental Management Plans for key regions that are visited by large ships.
Marine Risk Assessment: discharges from exhaust gas cleaning systems (scrubbers)
Read the reports and findings of the preliminary risk assessment of scrubber discharges.
The Ministry will continue to monitor the use of scrubbers in New Zealand waters. This includes gathering information on the nature and extent of scrubber use. We would like to hear further from interested groups as New Zealand signs up to Annex VI.
Further evidence, including from work undertaken by the international community, may result in the consideration of more stringent management controls once Annex VI has been implemented.
Read our guidance page for ship operators and port/regional authorities.