Sulphur cap compliance options increase CO₂ emissions, study shows

CE Delft research commissioned by three EGCS suppliers has shown an increase well-to-wake emssions for both types of sulphur cap compliance options and across vessel types. Running EGCS, commonly known as scrubbers, often generates a smaller increase in carbon emissions than the production and use of low sulphur fuels, the study’s authors said.

"In many cases, the emissions caused by producing low sulphur fuels for these ships are higher, depending on the quality of the low sulphur fuel, the refinery and the crude oil slate. This is the main conclusion from the new study Comparison of CO₂ emissions of Marpol Annex VI compliance options in 2020, a statement from the Netherlands-based independent research and consultancy said.

CE Delft said the fuel required to run EGCS caused an increase of 1.5 – 3% in vessel emissions.

"EGCS requires energy which is generated by engines running on fuel oil and thus generates carbon dioxide CO₂. In addition, there are emissions associated with manufacturing scrubbers and emissions from the seawater," the study said.

For VLSFO, the increase in emissions came from refinery processes such as hydrocracking to generate lower sulphur fuel oils. Desulphurisation in a refinery requires hydrogen which is generally produced from methane, emitting CO₂ in the process.

"The use of an EGCS results in an increase of CO₂ emissions between 1.5% and 3% for a range of representative ships," the report said. "The increase of emissions associated with desulphurisation in a refinery are higher than 1% and in many cases multiple times higher, depending on the quality improvement of the fuel, the refinery layout and the crude used."

The 1 January 2020 onset of Marpol Annex VI Regulation 14 placed a limit of 0.5% outside of Emission Control Areas (ECAs) on sulphur in marine fuels or requires vessels to run scrubbers to abate sulphur emissions of higher sulphur fuel oils.

Results from a CE Delft-led study for IMO in August 2020 showed that greenhouse gas emissions from global shipping are growing and are expected to continue to increase, rising as much as 50% by 2050.

In 2018, IMO agreed a milestone framework to reduce total annual global shipping emissions by at least 50% over 2008 levels by the middle of the 21st century.