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Open-loop scrubber usage in ships

Topics Covered: Conservation, environmental pollution and degradation, environmental impact assessment.

Open-loop scrubber usage in ships

What to study?

For Prelims: Exhaust scrubbers and about MARPOL.

For Mains: Sulphur pollution, concerns, challenges and ways to address them.

Context: According to GlobalData, a data and analytics company, there has been a huge increase in the use of open-loop scrubbers in ships in just last one year, even as a debate about their viability in mitigating sulphur emissions from ships has also escalated.

There are currently 3,756 vessels with scrubbers installed, compared to just 767 in 2018. Out of these, only 65 have closed-loop, rest are all open-loop.

How sulphur emissions are regulated?

The International Maritime Organisation’s (IMO) adopted the International Convention for the Prevention of Pollution from Ships (MARPOL) Annex VI in 2008 that regulates the prevention of air pollution from ships and prohibits deliberate emissions of ozone-depleting substances such as sulphur oxides and nitrous oxides.

What’s the issue now?

Following the adoption, exhaust scrubbers have become one of the most preferred ways of reducing sulphur exhaust as they ‘scrub’ pollutants out of emissions.

There are two types of exhaust scrubbers- open and closed.

While closed-loop scrubbers retain the sulphur emissions for safer disposal at port, open-loop scrubbers release pollutants back in the sea after turning the sulphur dioxide into sulphuric acid.

However, uncertainty around the sustainability of open-loop scrubbers continues to escalate in the shipping industry.

About International Convention for the Prevention of Pollution from Ships (MARPOL):

The Convention was adopted on 2 November 1973 at IMO.

It includes regulations aimed at preventing and minimizing pollution from ships – both accidental pollution and that from routine operations.

All ships flagged under countries that are signatories to MARPOL are subject to its requirements, regardless of where they sail and member nations are responsible for vessels registered on their national ship registry.

Sources: down to earth.