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Ships from the 1st of January 2020 onward will not be allowed to emit exhaust gases with a sulphur content of more than 0.5% as per the new IMO regulation (2020 sulphur cap) which will come into force. This is a significant milestone for the Shipping Industry since this new regulation will bring about huge benefits to human health.

According to a study at Yale University, about 70% of the maritime industry’s emissions take place within 250 miles of land, exposing people to harmful pollutants. Sulphur oxides (SOx) when diluted in the humidity of the air produce sulfuric acid, which return to the earth as acid rain. When acid rain reaches the sea it is neutralized by the natural alkalinity of the sea water. However, on land it can cause serious problems to humans and to the environment. Sox and acid rain can harm people’s respiratory systems and damage the lungs. Acid rain can destroy forests, may increase acidity of fresh water and damage life in the lakes. In addition, airborne particulate matter (PM), the tiny carbon particles that are emitted to the atmosphere by the internal combustion engines, are carcinogenic


Therefore, compliance with this new regulation must not be delayed. So, in order to comply with this new IMO regulation, shipping companies have the following acceptable methods/options:

1. Ships will have to burn compliant or alternative fuels.
2. Shipping companies will need to equip their vessels with exhaust gas cleaning systems (also known as scrubbers).

Each Shipping Company must decide which of the two methods/options it will follow to comply with this new IMO regulation.

To decide on the way to go forward the main questions that each Company will need to answer are the following:

 What are the risks of burning compliant or alternative fuels?


Many ship operators have expressed concerns about the risks arising when burning these new, untested fuels.The main reason is that a number of fuel characteristics that may vary as such new fuels may be blends of residual with distillate fuels. 


All Companies must carry out risk assessments so as to be prepared. It is the first time such fuels will be used on ships, therefore accidents could occur, because of engine failures and instabilities, and so it is vital for companies and manufacturers of engines to share the experiences/knowledge across the industry to avoid such incidents. Vessels must commence burning these compliant or alternative fuels the soonest for problems to be identified as early as possible. 


Nonetheless, it should ne noted that even today, most heavy fuels are blended products and most shipping companies have procedures of operations that avoid mixing. In addition, today all ships that call in Environmentally Controlled Area (ECA) ports are burning low sulphur fuels without significant problems. So some experience has already been built.


 Is using scrubbers environmentally friendly?

The main concern of the use of the scrubbers is if the wash-water used in the scrubbing process is harmful to the marine environment.

The scrubbing process within scrubbers, imitates what the natural process that occurs when it rains. Sox and PM are diluted in the air and with the rain they return either in the sea when neutralization occurs, or on land with harmful effects to the environment and human health. The scrubbing process within the scrubbers prevents the second part, i.e. the hazardous effects of the pollutants on land and to humans.

In addition, scientific research carried out over the past years (see below references) has come to the conclusion that wash-water from scrubbers has proven not to be a pollutant to the marine environment, as the produced sulfates which are the result of dilution of wash-water in the sea is already a natural ingredient of the sea water.

Furthermore, it should be noted that although scrubbers have been in the spotlight during the past year or so, scrubbing technology has been applied in the Shipping Industry for some time with satisfactory results. Scrubbers for SOx removal have been in operation in the global maritime sector for over ten years. Currently, hundreds of vessels are successfully using scrubbing technology to comply with the 2015 sulphur regulation in existing Sulphur Emission Control Areas (ECAs) under rules from the IMO/Marine Environment Protection Committee (MEPC) guidelines, as well as the EU Sulphur Directive, and US EPA Vessel General Permit and US Coast Guard Directives.

So which is the best alternative to comply with the new IMO regulation?

Both scrubbers and compliant or alternative fuels are equally acceptable, realistic and environmentally sound methods of compliance with the 2020 sulphur cap, and both are essential tools in significantly reducing the environmental impact of the maritime sector.

However, given the considerable cost and the complexity involved in the installation and use of scrubbers, it is expected that ship operators will opt for the least expensive option of consuming low sulfur content fuels, which however will require greater attention and awareness from users as safety concerns will mount.


(Source:  Nyman GBG Tokerud A. (1991). Seawater scrubbing removes SO2 from refinery flue gases. Oil and Gas Journal 89. 51-55).
(Source:  Andreasen, A. and Mayer, S.: Use of Seawater Scrubbing for SO2 Removal from Marine Engine Exhaust Gas, Energy Fuels 21, 3274–3279, 2007).
(Source:  COWI2012: Kjølholt, J., S. Aakre C. Jürgensen, J. Lauridsen Assessment of possible impacts of scrubber water discharges on the marine environment, (COWI, 2012) Danish Environmental Protection Agency). 
(Source:  Fridell, Erik & Salo, Kent. (2014). Measurements of Abatement of Particles and Exhaust Gases in a Marine Gas Scrubber. Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment. 230.10.1177/1475090214543716)
(Source:  Lack, DA, Thuesen, J, Elliot, R, Stuer-Lauridsen, F, Overgaard, S, et al. 2012 Investigation of appropriate control measures (abatement technologies) to reduce Black Carbon emissions from international shipping. IMO)
(Source:  CE Delft; The ICCT; Mikis Tsimplis, 2012. Regulated Slow Steaming in Maritime Transport: An Assessment of Options, Costs and Benefits, Delft: CE Delft)