The Ugly Truth: Cleaning the Air Leads to Polluting the Sea

A survey conducted by La Libre explores the impact of ships’ sulfur oxide (SOx) emissions and the solutions devised by the maritime industry to adhere to the emission control areas regulations imposed by the International Maritime Organization in 2008. The options ranged from using low sulfur fuel to using a purifier that filters SOx emissions. While the latter is legally acceptable and widely used, it is not environmentally friendly as the water used in the process is discharged into the sea, causing significant environmental impacts. Despite this, the number of ships equipped with scrubbers has increased rapidly over the years, with an estimated 30% of the world’s commercial fleet now using this “green” system. However, some states, including Belgium, now limit the discharge of washing water near their coasts. The report highlights the lack of coherence and ambition of the various actors involved in addressing the ecological, climatic, and economic issues arising from ship emissions.

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In 2008, the International Maritime Organization (IMO) created “emission control areas”, imposing limits on sulfur oxide (SOx) emissions from commercial ships. Several options then found themselves on the table of the maritime industry to adapt to the new rules, and limit its emissions.

First and logically: use a new type of fuel with very low sulfur content (less than 0.10%). Shipowners initially resorted to it, thanks to very low prices due, in particular, to the coronavirus crisis. But as soon as the prices of this “clean” fuel soared, they turned to a more profitable solution: the use of a purifier.

Totally and curiously legal, this device allows ships to consume heavy fuel, while filtering its atmospheric sulfur emissions to “clean” them. In itself, the system works: a majority of ships display results in compliance with the new regulations. But the water used during this process is then discharged into the sea in the vast majority of cases (80% of cases if we refer to European Union figures). Acidic, loaded with zinc, copper and nickel, it has a significant environmental impact.

Thirty percent of the world fleet equipped

However, the number of ships equipped with scrubbers has increased sixfold between 2018 and 2022. It is estimated that 30% of the world’s commercial fleet has such equipment and the European Investment Bank itself has invested hundreds millions of euros in the deployment of this supposedly “green” system. Although some States, including Belgium, now limit the discharge of washing water near their coasts, the inadequacy of this technique illustrates the total lack of coherence and ambition of the various actors in the face of ecological, climatic and economic issues.

Survey in the North Sea ©Raphaël Batista

This report was produced with the support of the Journalism Fund.



In conclusion, while the use of scrubbers has been widely embraced by the maritime industry to comply with emission control regulations, it has also caused significant environmental harm. The discharge of acidic wastewater into the sea has become a pressing issue, and even though some countries have taken measures to limit it, more needs to be done to address this mounting concern. The increase in the number of ships equipped with scrubbers and the investments made in this technology demonstrate a lack of coherence and ambition among stakeholders in tackling ecological, climatic, and economic challenges. It is incumbent upon all of us to work towards minimizing our carbon footprint and protecting our planet for future generations.

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