Scrubbers are considered one of the available methods of compliance with IMO's 2020 sulphur cap, aiming to reduce ship emissions. The regulation mandates that ships must run on fuel containing no more that 0.5% m/m of sulphur, unless they have a scrubber installed, which is used to remove particulates and gases from exhaust streams.

There are three types of scrubbers: Open-loop scrubbers use seawater to capture sulphur from engine exhausts before discharging this wash water back into the ocean after treatment. Closed-loop scrubbers are using water treated with additives, recycling the liquid internally. Hybrid scrubbers combine both technologies. Currently, open-loop scrubbers are the most popular as they are cheaper.

In a recent announcement, Andrew Tan, Chief Executive Officer of the MPA, said that the ban aims to protect the marine environment and ensure that the port waters are clean. In order to facilitate the implementation of the ban, Singapore would provide facilities to collect the residue generated from the operation of scrubbers.

However, EGCSA notes, the decision by MPA Singapore, a major port hub of the world, did not take into consideration 'the high risks to human health resulting from the high toxicity of low sulphur fuels and more toxic distillates if no exhaust gas cleaning systems are used', while the port authority did not provide neither scientific evidence for its decision nor was the industry invited to consultation.

As the pronouncement by the Singapore MPA is likely to have a significant effect on crude carriers operating inert gas plant discharging into Singapore refineries and storage facilities as well as all other vessels visiting Singaporean waters, it is disappointing that the Singapore MPA has been less than open about its plans and has not, as far as we can tell, based its decision on proven scientific findings. We would urge the IMO, national governments, port and harbour authorities to base any future decisions relating to the use of marine scrubbers, whether they use open or closed loop systems, on evidence and fact.

Moving further, EGSCA stresses, there have been no scientific studies published that indicate measurable harm to the marine environment by open loop scrubbers. For instance, Asia has adopted flue gas desulphurisation (FGD) for several power stations, including Mawan (1.8GW) in Shenzhen, Guandong province, China, Tanjung Bin (2.1GW) in Malaysia, Paiton (1.4GW) in Indonesia, Manjung (2.1GW) in Malaysia.

Port authorities should consider that the ban of open loop marine scrubber operations is likely to promote the use of low sulphur fuel oils using 0.10%S distillate which have been shown to have a significantly higher toxic impact than heavy sulphur fuel oils (HSFO). There is furthermore evidence from the refining industry and the IMO Secretary General’s Expert Group on sulphur to show that scrubbers emit 3%-5% less CO2 than low sulphur fuels over their lifecycle. A study by the University of Rostock furthermore identifies the exhaust emissions from low sulphur diesel fuels as posing a greater risk to human health than scrubbers.

One conclusion that may be drawn is that there is a significant difference between the discharge from an open loop EGCS to the discharge from an EGCS operating in closed loop mode. What is not clear however, or published by the MPA is their assessment of the differences and consequent measured or predicted environmental impact, EGCSA underlined.

The EGCSA welcomes dialogue and evaluation based on science and evidence. We encourage all ports to avoid the quick headline which is politically motivated and provides no measurable society benefit and instead to seek dialogue with the industry, conduct thorough investigations into all the available options for meeting the 2020 sulphur cap and to focus on sustainable solutions that will stand the test of time.

In other parts of the world, Chinese sources have recently reported that the country will eventually proceed with the ban of open-loop scrubbers along its rivers, following months of uncertaintly surrounding the issue. In Europe, open-loop scrubbers are prohibited in Belgium, in some states of the US -namely California and Massachusetts- as well as in Rhine river in Germany.