To Scrubber or Not to Scrubber?

With the 2020 Global Sulphur Cap of 0.5% fast approaching and uncertainty remaining over the likely cost, availability and even safety of low sulphur marine fuels, many operators are turning to the alternative emission reduction arrangement allowed under International Maritime Organisation (IMO) rules, namely exhaust gas cleaning systems (EGCS) or scrubbers.

Uptake of scrubbers has so far been slow, largely due to a combination of the cost and complexity of fitting the technology, so far largely unproven for maritime use. Scrubbers are bulky systems which require modification to ship designs, a reduction in cargo space and constant monitoring of their performance.

Additionally, with the three types of scrubber systems available, there is the problem of neutralising and disposing of the waste collected by so-called closed-loop systems. Open-loop systems deposit washwater effluent into the ocean, and hybrid systems are a mixture of the two types.

As at end May, close to 1,000 ships with scrubbers were in operation or on order, according to the EGCS Association. However, it noted that take-up was now beginning to accelerate, with a “slew” of recent reports of major ship operators choosing to adopt the technology.

These reports included an unnamed ‘big’ European container line that Wärtsilä said had placed a €170m (US$198m) order for retrofitting scrubbers to its fleet of container vessels.

Hyundai Heavy Industries of Korea, the world’s largest shipbuilder, reported that over 60% of newbuilds ordered during 1Q 2018 included scrubbers, compared to just 25% in 2016 and 2017, according to a senior Korean Register official quoted in Seatrade Maritime News.

The same official added that early adopters of scrubbers such as European ferry operator DFDS and several cruise lines were now expanding their orders to the rest of their fleets, showing they were satisfied with the performance of the technology which in some cases had been in operation since as far back as 2009.

Scrubbers come in various types and are a bit like large versions of the catalytic convertors fitted to cars. Attached to the smokestacks of ships, they typically work with a system of chambers where sea water is injected into the exhaust gases, thereby removing about 90% of their sulphur dioxide – as well as some 70% of particulate matter or soot, also harmful to human health. Cleaning agents such as caustic soda or magnesium oxide can be used to treat the washwater in closed-loop systems, whereas in open-loop systems, the effluent is neutralised by the alkalinity of seawater.

Speaking at the Posidonia exhibition in June, Stine Mundal, Head of Section for Environmental Certification at DNV GL – Maritime, confirmed that there had been a ‘dramatic’ uptick in the number of scrubber orders in recent months.

“This increase is due to several factors,” she said, “but the trend is clear. At the same time, we are seeing that bulk and container vessels are the segments with the most installations, overtaking cruise vessels which had been the early adopters. This indicates that owners are making their solution decisions now and many are choosing scrubbers to comply with emissions restrictions.”

Ms Mundal went on to dispel certain myths surrounding scrubber reliability. Scrubbers are in service and are working, with designs having improved since their first introduction, she said, while at the same time advising that ‘good system design and material selection is critical to minimise downtime.”

Scrubber technology may not be a long-term solution for environmental compliance because of “many uncertainties” – such as the aspiration for shipping to wean itself off fossil fuels altogether, she mulled.

“However, it might very well be a cost-saving and safe solution as the fuel market transitions into a ‘new fuel normal’ situation.”

Published On: 27 August, 2018