From July 1st this year, the Swedish government has decided to implement a ban on discharges from so-called scrubbers in Swedish territorial waters. For researcher Anna Lunde Hermansson at the Department of Mechanics and Maritime Sciences, this is an important step in the right direction. She and her colleagues have long pointed out the significant environmental risks and societal costs associated with scrubbers, and although she believes there are some questions surrounding the implementation of the ban, she is very pleased with the decision.
“On a national level, this is great, and I think we should be proud that we are now introducing a ban in Sweden,” she says. “It’s exciting and highly motivating to see that our research has been put to use and led to political decisions.”
With the ban, Sweden joins our neighboring countries Finland and Denmark, as well as countries like Germany, China, Portugal, and Turkey, which all have some level of ban on scrubber water discharge in parts of their waters.
“What is unique in the case of Sweden, Denmark, and Finland is that we are implementing a ban on discharges across the entire territorial waters,” says Anna Lunde Hermansson. “For example, Germany ban discharges in inland waters, and there are also bans in individual ports. But expanding to territorial waters in this way is unique, and a joint ban in large parts of the Baltic Sea region means it can have a greater impact.”
A two step implementation
The government’s decision is being implemented in two stages. The first step is set for July 1st, 2025, when so-called "open loop systems" will be banned from discharging scrubber water, and a total ban – including "closed loop systems" – will be implemented from January 1st, 2029.
“Open loop scrubbers are the most common system, and the system that discharges the largest volumes of scrubber water,” says Anna Lunde Hermansson. “A ship equipped with an open loop system discharges hundreds of cubic meters of heavily polluted water every hour.”
Anna Lunde Hermansson and her colleagues at Chalmers have worked with the issue of scrubbers for a long time, in close dialogue with the Swedish Transport Agency and the Swedish Agency for Marine and Water Management. They have also been part of the Swedish delegation at meetings with the IMO (International Maritime Organization). In several scientific papers and publications, they have pointed out the great environmental hazard of discharging scrubber water into the sea, and the significant costs that the discharges entail.
Shipowners supportive of a ban
She emphasizes that although Sweden is not the first country to introduce a ban, Sweden has been a frontrunner in other ways when it comes to scrubbers.
“Swedish shipowners who have chosen not to invest in scrubbers have generally been very supportive of a discharge ban,” she says. “They have chosen to use different fuels instead of installing scrubbers, and although I am not an advocate of fossil fuels, that fuel at least releases fewer heavy metals and organic substances compared to the heavy fuel oil used on ships equipped with scrubbers.”
Want to see a global ban
Anna Lunde Hermansson sees the ban as a big and important milestone, but she believes there are still several steps to be taken. Above all, she wants to see a global ban on scrubbers.
“A national ban means that ships that have operated here will probably be moved somewhere else where scrubbers can still be used,” she says. “So, there is a risk of increased pollution elsewhere. Then, one can consider how compliance with the regulations will be ensured and what the consequences will be if the rules are violated, these are things that will be revealed after the ban is implemented. But at the same time, it is very gratifying to be part of the change, and my colleagues and I often remind each other that a lot has happened in this area in a relatively short period of time.”
About scrubbers
A scrubber can be simply described as a system that removes sulfur from the exhaust gases produced by burning heavy fuel oil, the most common ship fuel for several decades. Seawater is pumped up and sprayed over the exhaust, preventing the sulfur oxides from reaching the air.
The problem is that when the water scavenge sulfur from the exhaust, sulfuric acid is formed,, and pollutants such as heavy metals and toxic organic compounds are also scavenged by the scrubber water. The highly acidified and polluted scrubber water is then often pumped directly back into the sea.
Scrubbers can broadly be divided into open loop systems, closed loop systems, and hybrid systems that can switch between open and closed loop mode. The open loop systems are the most common and discharge the most scrubber water. The closed loop systems also discharge water, but in lower volumes – however, the water is circulated several times within the system, resulting in enhanced enrichment of harmful substances when compared to the water discharged from an open loop system.
Chalmers research on scrubbers
Marine environment at risk due to ship emissions
Millions in costs due to discharge of scrubber water into the Baltic Sea
Research reveals large emissions from ship scrubbers
Anna Lunde Hermansson's PhD thesis: “Holistic assessment of ship scrubbers, with emphasis on the marine environment”
About Chalmers’ thematic area Ocean
In Chalmers' thematic area "Ocean" all research related to marine and maritime sciences is gathered, fields in which Chalmers has a long and strong tradition. The work is carried out in several of our departments and includes various aspects of the blue economy, such as value enhancement of marine raw materials, marine spatial planning, and risk assessments of offshore activities. Read more on the Ocean website
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