Facts and fears in the open loop scrubber debate

Recent local bans on scrubber washwater discharges from open loop systems have increased a widespread misconception that there are no safeguards against their environmental impact.*
This has created uncertainty about the viability of this particular solution to reducing sulfur emissions from ships at a time when the market is already under a lot of stress about how to cope with the 0.5% sulfur limit taking effect at the start of 2020.

IBIA has made observations and given background to help clarify the situation, which is summarised as follows:

  • The IMO’s EGCS Guidelines have established washwater discharge and monitoring criteria to safeguard against environmental damage.
  • Regulatory decisions should be based on sound science to assess environmental impacts.
  • Environmental impacts of washwater discharges depend on local factors.
  • Local authorities may take a precautionary stance but a global washwater discharge ban is currently not on the cards.
  • Scrubbers play a role in global fuel availability to comply with the 2020 sulfur limit.

IMO scrubber regulations

Currently the use of systems using water to clean ship exhaust gases, both open and closed loop scrubbers, is allowed under MARPOL Annex VI. Bleed-off water from closed loop systems can also be discharged as washwater after on board treatment, or fed to a holding tank for later discharge if a zero discharge mode is required.

No proposals have been made to prohibit their use even if there are some parties calling for water discharge bans on the basis of concerns about the environmental impact.

IMO might eventually go that way, but it would need to be formally proposed by one or more member states and go through the process of regulatory amendments.

New research

Recognising that a ban on washwater discharges from scrubbers would be a serious blow to shipping companies that have invested millions in them, any proposal and subsequent decision would need to be supported by new research demonstrating that the washwater causes unacceptable environmental risk.
As mentioned, the IMO has established EGCS Guidelines, which include washwater discharge and monitoring criteria to safeguard against environmental damage. These were first issued in 2009, they were updated in 2015 and they are currently under review to be refined further.

The discharge criteria remain the same so the review is chiefly to clarify issues around monitoring of washwater, emission testing and approval of scrubbers. This should help ensure that the monitoring of EGCS washwater is effective to ensure the discharge criteria are met.

EGCS role

The IMO’s decision to implement the 0.5% sulfur limit in 2020 hinged in part on the ability of a portion of the global fleet to be compliant by using EGCS in combination with burning HSFO.

This decision taken by the IMO in October, 2016 was based on an availability study, which used a model predicting that ships with scrubbers would be burning some 36 mill tonnes of HSFO, accounting for 11 % of total global marine fuel demand in 2020.

That forecast may be too high, as orders were slow to take off until the second half of 2018, but a portion of the fleet will be ready in time and more will come on stream during 2020, reducing some of the demand on global refining capacity to produce sufficient compliant low sulfur fuels to meet global marine fuel demand.

With less than a year before the global bunker fuel sulfur limit falls from 3.5% to 0.5%, there is still a lot of uncertainty in the market as to whether there will be sufficient compliant fuels available in 2020.

Supply pressure

A number of refinery modelling experts say it will be tough even if refiners make a concerted effort to meet demand from the marine sector, and there is no doubt that implementing such a dramatic global fuel specification change over a short period of time will create pressure on supply.

This is not a good time to sow doubts about the feasibility of open loop scrubber installations, as that will increase the pressure on low sulfur fuel supply.

Even with major ports like Singapore and Fujairah banning scrubber washwater discharges, ships will still be able to use open loop scrubbers at sea, which accounts for most of their fuel consumption.

As such, owners that have opted for open loop scrubbers will still be able to use them as their primary MARPOL Annex VI compliance option, but will need to use compliant fuels or systems that can operate in completely closed loop mode in locations which prohibit washwater discharges.


*This article was written by Unni Einemo, Director, IBIA and first appeared on the association’s website.



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