Page 43: of Maritime Reporter Magazine (May 2021)

TECH FEATURE SCRUBBERS tion phase, these materials might not be the cause, but they can contribute in the ? re propagation.”

Conversely, the reliability of some scrubber systems can be challenged in ice conditions, Somerkallio says. “If separate sea chests are built for the scrubber system, for example, there is a risk of sea water intake getting clogged when the ship is sailing in ice condi- tions, as warm scrubber water cannot be recirculated back to the sea chest to keep it free from ice.”

Open to Persuasion

The majority of the hybrid systems the company has worked on have been destined for cruise ships or RoPax ves- sels, where vessels spend more time op- erating coastally and in-port. However, lower cost open loop scrubbers have represented a larger part of the compa- ny’s workload, with owners switching to lower sulfur fuels where port restric- tions on washwater demand it. “It’s understandable that some local au- thorities take a negative view on acidity in washwater and the presence of heavy metals, no matter how low the concentra- tions, especially where water exchange rates are not high,” said Somerkallio. “Hybrid scrubbers that switch to closed hybrid systems, and owners that have coastal waters block their use. While the loop operations certainly provide one committed to this technology are report- ef? ciency indexes driving IMO regu- option but the other remains to install an ing returns on investments far more rap- lations favor LNG over HFO, Decem- open loop system and manage a switcho- id than anticipated, Somerkallio reports. ber’s Marine Environment Protection ver to low sulfur fuels in port.” “When oil prices recover, we expect this Committee nonetheless pointedly re-

The combination of Covid-19 and cut- type of scrubber to attract signi? cant placed the phrase ‘liquid ef? uents’ with throat oil pricing has eaten into the dif- new investment.” ‘discharge water’ in its latest scrubber ferential between high sulfur and low sul- guidelines evaluation.

Scrubbers stay global fur content fuel oils, leading demand for Somerkallio adds that new research scrubbers to stall. The circumstances has “For cargo ship owners, the fact that from Tampere University, the Finnish also had consequences for future scrubber the closed loop needs alkali in signi? - Meteorological Institute and the VTT technology demand, said Somerkallio. cant volumes will always make it an Technical Research Centre show that

The cruise ships needing hybrid scrub- expensive option. Although lower fuel using exhaust gas cleaning systems in ber systems to accommodate closed cost in port can shift the economics combination with HFO result in lower loop operations in waters identi? ed as in favor of the hybrid option for some particulate emissions than marine gas oil. especially sensitive had already been ships, for cargo ships the cost of the “Whatever the critics might say, if equipped, while Covid-19 ad driven closed loop operation kills the econom- there was an outright ban on the open some older vessels that might have been ics of the scrubber.” loop, I believe there would only be a hybrid candidates to scrap. Somerkallio acknowledges that criti- very small number of scrubber instal-

The total cost of open loop scrubbers cisms are leveled at open loop scrub- lations altogether each year. I don’t be- including equipment and installation is bers based on sulphurous washwater but lieve that would be an environmentally signi? cantly lower than is the case for emphasizes that only speci? c ports and desirable outcome.” www.marinelink.com 43

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