Marine Exhaust Gas Scrubbers – An Environment friendly solution!


Marine Exhaust Gas Scrubbers – An Environment Friendly Solution!

2795F4C3-A8FA-69A9-CD7D-726E8B24BF78.jpgSome environmental groups have issued statements saying that the benefits of scrubbers as a compliance route to regulatory requirements are overstated.  Spokespersons for these groups suggest that nobody has systematically investigated the impact of scrubbers on the marine environment before adopting this technique as a proper solution to meet the regulations.  It is their perception that using scrubbers amounts to discharging harmful substances into the ocean instead of to the air.

How Misleading!

Everyone agrees that sulphur in the fuels get converted to oxides of sulphur during the combustion process and these oxides when discharged into the air have a profound damaging effect on the human health, affecting our lungs.  They also result in acid rains affecting freshwater and vegetation.  Use of expensive low sulphur fuels and exhaust gas scrubbers can be a sort of dual solution to overcome this issue.  A Well designed exhaust gas scrubber will scrub oxides of sulphur from the exhaust gas completely.

Scrubbing is carried out using the seawater or alkaline freshwater.  Alkaline fresh water is obtained by addition of alkali, such as NaOH to the freshwater.

In the process the oxides of sulphur get converted to Sodium Sulphate which can be discharged into seawater, where the sea water already contains large quantities of Sodium Sulphate.  In addition, the scrubbers also remove particulate matters.  This particulate matter thus removed can be filtered, dried and used in making bricks.


Further in a good design of scrubber, the pH value of scrubbed water discharged overboard is controlled, so as not to harm the marine life and not to damage the protective coatings on the ship sides.

To say that through the use of scrubbers, the pollution has shifted from air to sea is absolutely baseless and those making such statements have not been properly informed of or have understood the operation of scrubbers.

Raghuvir C Bhavnani
Viswa Lab


  1. With the compliance of forthcoming sulphur regulation, Year 2020 could expected to be a mile stone on Marine fuel pricing. Residual fuel is the left over by-product of refining process. In order to continue with the distillation process, most of the refineries are to continuously pump out the accumulated residual fuel to make space for distilling their cash crop like Gasoline, diesel, naphtha, aviation fuel, kerosene etc. It is not economical to store residual fuel longer, as heating cost money and it can deteriorate in long time in storage. Transportation is also costly.

    Usage of MGO and Ultra Low sulphur fuel will increase and that much of additional residual fuel will be left unsold. Supply /demand gap will increase and refineries have to some how get rid of the accumulated residual fuel. There could be a downward price war for 3.5% Sulphur residual fuel.

    Let us do an approximate estimation:
    Based on US$ 280/MT Current crude price (US$44.50/ barrel) the 380 cst residual fuel is about USD 230/Mt, which is $50 cheaper than crude when MGO price is $470/MT. That makes the residual fuel $250 cheaper than the MGO. More crude is to be distilled to meet increased usage of MGO and ULSFO. That much extra residual fuel will be accumulated with refineries and they will be forced to sell at any cost at which they could get rid of the Residual fuel to make space for continued distillation. Besides, since more ships will be using LSFO or MGO, and some on LNG, consumption of residual fuel will drop further. Based on this estimation, we could expect a large stock pile of residual fuel, leading to a steep drop in price.
    Understand the newly formulated ULSFO could be $50/MT cheaper than MGO, and comes with some operational restrictions like lubricity, viscosity etc.

    Such scenario makes scrubber installation / retrofit most advantageous. Scrubber could drastically lower overall operation cost for owners and charterers. Considering 60% of the operational cost of a shipping company is spend on bunker fuel, it is worth studying this option to remain competitive and sustainable in the transportation market.

    Well, above observation is based on a layman’s thought. A serious discussion involving all parties in this forum will certainly benefit shipping community as a whole, to operate their fleet more cost effectively and remain competitive in current cut throat market.