There are multiple reasons why it is advantageous to treat marine exhaust gas streams with a closed-loop scrubber, but there are three significant reasons, which are worth highlighting.

1) Compliance

More and more environmental regulations are adopted to obtain a cleaner shipping industry, including the sulfur cap limit of 0.1 % for the Emission Control Areas (ECA) and, more recently, the IMO 2020 sulfur cap on 0.5 %. And with the great, current emphasis on sustainability, more regulations are expected to enter into force.

See the below video to get a grasp of the timeline of the international mandates in the marine industry.


The marine industry is an industry moving towards zero emissions. Currently, there is a massive focus on reducing sulfur oxide (SOx) emissions, which scrubbers can ultimately do. All current regulations on SOx reduction are vital to comply with as the local authorities monitor all vessels’ operations. Violations of the IMO 2020 involve severe punishments, which can be costly and cause delays, which will obstruct your operation.

The shipping industry has two options to comply with current SOx regulations:

Option 1: Switch to a compliant fuel containing a lower amount of sulfur, such as low sulfur fuel oil (VLSFO), or an alternative non-sulfur fuel such as methanol, liquified biogas (LBG), or liquified natural gases (LNG)

Option 2: Implement a scrubber technology to lower the SOx output and continue to operate on heavy fuel oil (HFO)

It is essential to comply with environmental regulations, which both methods can ultimately do. Yet, by retrofitting a vessel’s machinery with a closed-loop scrubber, you can reduce its SOx emission from the previously allowed 3.5 % to the currently allowed 0.1 % m/m (mass by mass), ensuring that your vessel can also operate within the ECA. 

Currently, over +120 ports worldwide have banned open-loop scrubber discharge, and we are soon facing a global ban for open-loop scrubbers, stressing that closed-loop scrubbers are the future. IMO and the EU and other regulatory institutions are tightening regulations for open-loop discharge.

open-loop-scrubber-ban-world-map-liqtechMoreover, closed-loop scrubbers bring about financial gains and a sustainable outlook, which takes us to the next reasons for using a closed-loop scrubber.

2) Financial Gains

Retrofitting to or installing a closed-loop scrubber is a cost-intensive solution. Still, it brings about a significant market advantage as it provides returns in fuel cost savings. You can continue to operate on cheaper HFO rather than more expensive low sulfur fuel with a scrubber. Thus, a closed-loop scrubber ensures low OPEX, condoning the CAPEX and making it the most competitive solution long-term.

Whether a closed-loop scrubber is a profitable solution highly depends on the fuel price spread, which constantly changes. Still, the price spread may easily be triple-digit per metric ton (mt). When the spread hit its highest on the 3rd of January 2020, at $321.5/mt on a FOB Rotterdam barges basis, the return on investment (ROI) was less than 6 months. Still, a conservative return on investment is typically 1-3 years, which still secures an advantageous financial outlook for scrubbers.

Return on investment depends on:

  1. CAPEX: The capital expenditure and the installation cost of the closed-loop scrubber
  2. Fuel consumption in the ECA per year
  3. The price spread between HFO and alternative low sulfur fuels

3) A Sustainable Outlook

Closed-loop scrubber technology is a market-proven and environmentally sound solution. The research and analyst firm CE Delft, which is specialized in assessing innovative solutions for environmental problems, has conducted a study comparing CO2 emissions from producing and installing scrubbers with CO2 emissions from producing and using refined marine fuel. To this comparison, CE Delft could conclude that scrubbers result in a 1.5-3 % rise in CO2 emissions for a variety of relevant ships. Concurrently, using low sulfur fuel results in a 1-25 % rise in CO2 emissions. Consequently, scrubbers have a significantly lower carbon footprint than alternative fuel options.

On that account, you obtain a long-term sustainable solution, which is always compliant, cost-effective, and durable. Read more about the differences between open-loop scrubbers, closed-loop scrubbers, and hybrid scrubbers.

By implementing a closed-loop scrubber, you embark on an improved future and take an active role in reducing world pollution. Lowering SOx emissions will benefit the environment and all people and wildlife. This will primarily benefit the people living in port cities and coastal areas of Asia-Pacific, Africa, and Latin America. The IMO 2020 sulfur cap will deliver a 77 % decrease in overall sulfur oxide emissions from ships, corresponding to a yearly drop of approximately 8.5 million metric tons of SOx emissions. Moreover, particulate matter (PM), which are small harmful particles formed once the fuel is burned, is also reduced. As a result, the cases of several severe diseases, such as strokes, asthma, lung cancer, and cardiovascular and pulmonary diseases, are expected to decrease significantly. Lastly, reducing SOx emissions is also expected to prevent acid rain and ocean acidification and improve the conditions for crops, forests, and aquatic species.

A closed-loop scrubber can be installed as a new system or by retrofitting open-loop scrubbers to closed-loop scrubbers. Learn more about open-loop to closed-loop conversion here.

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