Singapore Announces Ban on Open-Loop Scrubber Discharge

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Published Nov 30, 2018 9:46 PM by The Maritime Executive

On Friday, the Maritime and Port Authority of Singapore (MPA) announced that it will not allow ships with open-loop scrubbers to discharge scrubber wash water in port after January 1, 2020. In order to remain in compliance with the IMO 2020 fuel sulfur limits, these vessels will have to burn more costly 0.5 percent sulfur fuel when calling Singapore, just like ships that are not equipped with scrubbers. 

The discharge ban will have a lesser effect on ships fitted with hybrid scrubber systems, which can switch from open-loop to closed-loop mode and retain their wash residues on board. Singapore will offer a full range of services for shore reception of closed-loop scrubber residues.

"To protect the marine environment and ensure that the port waters are clean, the discharge of wash water from open-loop exhaust gas scrubbers in Singapore port waters will be prohibited," said port CEO Andrew Tan in a keynote speech Friday. "Ships fitted with open-loop scrubbers calling at Singapore will be required to use compliant fuel. Ships fitted with hybrid scrubbers will be required to switch to the closed-loop mode of operation. Singapore, as a party to MARPOL Annex VI, will be providing reception facilities for the collection of residues generated from the operation of scrubbers."

According to Tan, the MPA will release a larger set of guidance by the second quarter of 2019 that will give a full description of Singapore’s preparations for the IMO 2020 regulations. It will provide information on compliant fuel availability in Singapore, reception facilities for scrubber residues, and enforcement measures. Tan emphasized that his agency is conscious of the need to "ensure there is no disruptive impact to shipping.

Singapore's ban occurs within the context of a broader conversation about the potential effects of scrubber washwater on the marine environment. Wet scrubbers allow vessels to continue to burn low cost, high-sulfur fuels, even where otherwise prohibited, by removing sulfur oxides from the exhaust stream. Open-loop scrubbers use seawater as the washing agent, then discharge it again after use, along with some of the substances that would ordinarily exit the vessel's stack as air pollutants.

In a recent review, naval architecture consultant Jad Mouawad advised that more research will likely be needed to answer questions about scrubbers' impact. "A quick analysis of the concerns raised with washwater from scrubbers indicate that more independent research and a more thorough analysis of the environmental risks those systems pose is needed. This applies regardless of whether the system is open, closed or hybrid," he concluded. "My strong recommendation is that the IMO member states put forward suggestions to that regard, rather than start applying restrictions on scrubbers."