· Potential reduction of NOx by an amount of 95%

· Relatively simple installation

· Expensive

· Catalyst may suffer from erosion caused by flue gases

· Requires enough space that can be complex or not feasible for retrofit applications

[38] [39]

Open loop scrubber

· High Sulphur dioxide (SOx) removal efficiency (up to 98%)

· Offers the possibility to use the cheaper bunker fuel than medium or low Sulphur fuel

· Reduce the PM by 60%

· Subject to corrosion (seawater)

· Requires regular maintenance

· Requires additional electric power to run seawater and pumps

· Not suitable for vessels operating in fresh water

· Increases ship fuel consumption

[34] [35] [36] [37]

Closed loop scrubber

· Requires storage space to hold waste water and hazardous chemical solutions

· High consumption of fresh water

· Crews must be trained to manipulate waste water and chemical solutions

[34] [35] [36] [37]

Ecospec CSNOx

· Potential reduction of NOx by 65%

· Potential reduction of SOx by 99%

· Potential reduction of CO2 by 77%

· Possibility to continue using heavy fuel oil (HFO)

· High investment cost

· Requires additional generator power

· Machinery and stacking arrangements: for retrofits, fitting this equipment into existing spaces will be a major challenge

[34] [35] [36] [37]