Scrubbers Beat Compliant Fuel in Race to Reduce CO2 Emissions

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Published Sep 22, 2020 5:58 PM by The Maritime Executive

As part of their ongoing commitment to support greener shipping, Yara Marine has jointly commissioned a report to quantify the climate impact of scrubbers compared to low sulphur fuel oil.

“Well-to-wake, using HFO as fuel in combination with scrubbers generates less CO2 than using compliant fuel,” says Kai Låtun, Director in Yara Marine Technologies. He notes the report shows that use of compliant fuel could potentially generate as much as 25% increased CO2 emissions  (see attached graph from the CE Delft report). “In real life this is probably not the case, but there is no doubt that using compliant fuels, all things considered, will result in three to five times higher CO2 emissions than using HFO as fuel in combination with scrubbers.”

In practice, there are two options for achieving compliance with MARPOL Annex VI Regulation 14. The first is using an exhaust gas cleaning system (EGCS) in combination with fuel oils with sulphur content higher than 0.50% or 0.10%. The second is burning fuel oil with a sulphur content of 0.50% / 0.10% or less.

Both options result in an increase of well-to-wake CO2 emissions. Operating an EGCS requires energy from engines running on fuel oil, thus generating CO2. Emissions associated with manufacturing scrubbers and discharge of washwater during operation are also factors. Desulphurisation in a refinery requires hydrogen, generally produced from methane, requiring energy and emitting CO2 during the process.

The study by CE Delft shows that CO2 emissions associated with using an Exhaust Gas Cleaning System (EGCS) vary between 1.5% and 3% for a representative number of ships. In comparison, use of fuel with 0.5% sulphur content will generate somewhere between 1% and 25% increased CO2 emissions. Use of compliant fuels with even less sulphur content, such as MGO with 0.1%, will result in even higher CO2 emissions, as they require considerably more energy to produce.

The Delft report quantifies and compares the CO2 footprint of both options, with scrubbers emerging as the overall winner in comparative CO2 emissions. Jasper Faber, Director aviation and shipping, and manager of the report at CE Delft, says: “This study provides a comprehensive overview of the climate impacts of different options to reduce sulphur emissions. It shows that in many cases, the carbon footprint of using a scrubber is lower than low-sulphur fuels.”

The study, Comparison of CO2 emissions of MARPOL Annex VI compliance options in 2020’ issued by CE Delft,was commissioned by Alfa Laval in cooperation with Yara Marine and Wärtsilä.

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