Scrubber maker may find use for sludge and calls for more scientific studies

Malcolm Latarche

Malcolm Latarche · 08 March 2019


Norway-based scrubber maker Yara Marine Technologies has called for more scientific studies into scrubber use and is itself involved in a project that could find a use for the sludge produced during operations.

Discussing the use of scrubbers and recent restrictions on the use, Yara Marine Technologies R&D Manager Shyam Thapa said, “Some studies have shown that open loop bans have no real environmental impact, while others maintain that the effects of wash water on marine life have yet to be assessed or may even be harmful. Regardless of this there are different reasons for enacting bans. Open loop scrubbers do not perform effectively in water with low alkalinity, such as rivers and inland waterways. In these areas, systems supplying alkali in a closed loop are required, so open loop bans are largely formalities.”

Some private ports are also enacting open-loop bans, but Thapa observed that this may often be for reasons other than environmental concern. He believes that a combination of ‘want to’ and ‘need to’ is a likely future scenario on open loop scrubber bans, with flexibility being the common key to ensuring compliance and unrestricted operations.

Yara Marine manufactures both open and closed loop exhaust scrubber systems, and hybrid scrubbers capable of operating in either mode depending on applicable geographical regulations. “Open loop is still viable for 80-90% of global marine transport,” Thapa pointed out. “Our estimates for hybrid solutions assume maximum 15% of operation time using closed loop mode. But if the vessel is operating in waters where open loop is forbidden, owners either need to be able to operate the scrubber in closed mode or switch over to alternative fuel.”

For those still pondering their options, Thapa is sympathetic. “I think the main thing is to emphasize that the overall picture is more complex than what is presented in the media. There are many factors in the calculation, and each case is different. There is no blanket solution for every situation.”

International research continues into the effects of scrubber washwater discharge to the sea. Several major shipowners have been collecting data from their own fleets as well, and all will have to be considered before consensus can be reached on the ultimate consequence of open loop scrubbers for marine environments. For its part, Yara is involved in an ongoing research project with Chalmers University of Technology to combine SOx and NOx gas cleaning in a single system. The project is also investigating possible industrial uses for exhaust sludge. The results could be applicable for both marine and land-based applications, giving the project wider environmental significance. Yara is also working intensively to solve the issue of particulate matter (PM) from combustion processes. The goal is to reduce harmful PM smaller than 2.5 micron by more than 95%.

Yara Marine Technologies CEO Peter Strandberg encourages further investigation into scrubber options, supported by more hard facts: “We want to see more independent research to move the debate forward, and we invite owners and operators who are uncertain about the best scrubber solution for them to contact us. With our flexible technology, Yara Marine can help owners and operators comply, whatever the abatement requirement.”

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