Use of scrubbers on the Baltic Sea and in Polish ports.
Scrubbers are exhaust gas cleaning systems (EGCS) approved as an alternative to low sulphur fuel oil for seagoing ships. Seawater is sprayed into the exhaust gas to wash out the sulphur. In addition to the washed-out sulphur, other pollutants such as heavy metals, oil residues and also polycyclic aromatic hydrocarbons (PAHs) get into the wastewater. This water mixture of partly long-lived and carcinogenic pollutants is often discharged into the sea almost unpurified and thus pollutes the marine environment.
International Maritime Organization (IMO) regulations dictate strict limits on sulfur content in fuels carried by ships, with a ceiling of 0.50% and 0.10% m/m in Emission Control Areas (ECAs), including the Baltic Sea area, the North Sea area, the United States, Canada, and the United States Caribbean Sea area
Why the instalation is called a „scrubber”?
Because exhaust gases are scrubbed from the pollutants. (It is also the insulting word in its other meaning so pleases be aware of that)
In other words the scrubber technology shifts pollutants from air to water.
The purpose of this blog post is not to elaborate in detail on technical aspects of scrubbers technology but some basic information can be beneficial for clarity of further information:
Open Loop Scrubber System:
This system uses seawater as the scrubbing and neutralising medium, no other chemicals are required for desulphurization of gasses. The exhaust stream from the engine or boiler passes into the scrubber and is treated with only alkaline seawater only. The volume of this seawater depends upon the size of the engine and its power output.
The system is extremely effective but requires large pumping capacity as the amount of seawater required is quite high. An open loop system works perfectly satisfactorily when the seawater used for scrubbing has sufficient alkalinity. However, sea water which is at high ambient temperature, fresh water and even brackish water, is not effective and cannot be used. An open loop scrubber for these reasons is not considered as a suitable technology for areas such as the Baltic where salinity levels are not high.r.
Closed-loop Scrubber System:
The water is used several times, partially cleaned and can be stored on board in tanks for a certain period of time.
Despite their name, closed loop scrubbers are rarely entirely closed systems; most often there is a bleed off, i.e. a small volume of washwater being discharged to the marine environment to allow for addition of base (typically sodium hydroxide) that is essential to maintain the sulfur oxide removal capacity in the scrubber process. World-wide there is only a handful of closed loop scrubbers where the ships leave all the produced sludge and scrubber water ashore for destruction instead of discharging the bleed off to the marine environment. Although the bleed off volumes are smaller (typically a few cubic meters per hour) compared to the discharge volumes from open loop scrubbers, the concentrations of pollutants, especially metals, are often much higher in the bleed off. This is due to recirculation of water in the closed loop system, which means the pollutants are enriched over time. The recirculation enables possibility to separate parts of the pollutants, especially pahs that are often to large extent associated with particulate matter. To maintain the removal capacity of sulphur oxides, strong base (often sodium hydroxide) is added continuously to the water in the closed loop scrubber process. Thereby the local acidification of the marine environment is not as pronounced as following discharge of open loop scrubber water, but the load of other pollutants may still be significant
If this discharge water is not disposed of in the harbour, but is discharged outside of prohibited zones, It is feared that hot spots, areas with particularly high pollution levels, will develop ther
Hybrid Scrubber System:
The hybrid loop system can run in both Open and Closed loop mode. The process water is either re-circulated or directly discharged back to sea. Switching between open and closed mode is done by using remotely controlled valves.
Hybrid loop systems are primarily used for vessels that operate mainly at open sea, but also considerably in ports and sailing areas where overboard discharge is prohibited.
Although it combines the advantages of open-loop and closedloop scrubbers, the biggest advantage of hybrid scrubbers is the flexibility they offer for operation regardless of the alkalinity of the area’s water. So when the ship is in a marine environment with high alkalinity, it operates in open-loop mode without the use of chemical additives. In contrast, in areas with reduced alkalinity it operates in closed-loop mode with the corresponding disadvantages and advantages. But the biggest disadvantage of hybrid scrubbers is the increased cost compared to open-loop and closed-loop scrubbers
Usage of Scrubbers in the Baltic Sea:
The Baltic Sea is considered particularly sensitive to pollution due to its semi-enclosed character with low salinity, long retention time for contaminants, low biodiversity and limited food-web with few key-species.
The study of Chalmers University of Technology (SWE) showed that scrubber wash water accounts for up to 9% of the emissions of certain cancer-causing polycyclic aromatic hydrocarbons (PAHs) into the Baltic Sea.
There is an icontinously increasing number of countries or ports in the Baltic Sea basin where using of scrubbers is limited or restricted. Please allways make sure that you are up to date with the recentt changes.
Polish Ports: as of January 2024
Fully operational, certified Open Loop type scrubbers reducing sulphur emission to 0,1% can be used on the Polish territorial waters of the Baltic Sea (including roads).
According to the latest guidelines of the Gdansk
Harbor Master’s Office, the use of EGCS Open Loop scrubbers is prohibited when entering the port and within the port area.When a vessel is operating on an open loop system, it has to be reported to the Harbor Master’s Office on VHF ch 14
In Gdynia, Szczecin and Swinoujscie ports use of Open Loop scrubbers is still permitted.
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