THE FACTS ABOUT THE ENVIRONMENTAL IMPACT OF EXHAUST GAS CLEANING SYSTEMS

A number of sensationalist and poorly researched mass media articles with grave factual errors have recently aimed at creating alarm about the use of exhaust gas cleaning systems (EGCS), claiming that they dangerously pollute sea water.

The facts of the matter are quite different. Exhaust gas cleaning systems, also known as “scrubbers” are legal appliances that are in full accordance with all maritime regulations and that have to meet strict turbidity controls, both facts ignored by the press.

Clearly, the EGCS technology is too complex for many non-specialist journalists to understand. Scrubbing does not merely remove the pollutant from the exhaust gas and “dump it into the sea” but transforms the pollutant (sulphur oxides – SOx) into a non-polluting compound (sulphates – SO4) and only then releases it into the sea, where it is a natural constituent. All scrubber systems also have compulsory monitoring equipment to limit discharge of contaminants such as PAHs. Another issue that seems to have caused unease is the temperature of the scrubber discharge water. This is typically 2-4% warmer than the ambient temperature, but considerably cooler than a ship’s engine cooling water which is also discharged into the sea without triggering any concerns.

While there is an increase in CO2 emissions when using an EGCS (approx. 1-2%), this is 10-13% lower than the overall CO2 emissions of compliant fuel used in shipping. Fuel with a 0.1 or 0.5% sulphur content entails a 12-15% CO2 penalty at the refinery. It is important to consider the entire lifecycle when analysing the overall impact of EGCS compared to low sulphur fuels.

For a summary of the EGCA’s stance on pollution control, market readiness and the ban on open-loop scrubbers by certain ports, see the interview which appeared in World Maritime News: https://worldmaritimenews.com/archives/285373/interview-demand-for-scrubbers-to-last-at-least-30-years-egcsa-says/