- China proposes setting a limit of less than 1% for fuel oil residue/sludge to improve the accuracy of CII calculations.
- China’s study found sludge levels on ships ranged between 0.39% and 2.26%, potentially increasing with poor quality blended fuels.
- The proposal will be discussed at the upcoming IMO’s MEPC 82 meeting in London.
China has proposed that residue or sludge content in fuel oil should be restricted to less than 1% to prevent it from skewing the fuel oil consumption data used in calculating a vessel’s Carbon Intensity Indicator (CII), reports Engine.
Factors Influencing Sludge Levels
The proposal argues that setting a maximum sludge limit would improve the accuracy of fuel consumption reporting.
“The maximum quantity of residue/sludge to be subtracted from the fuel oil consumption of a certain reporting period should be less than [1%] of fuel oil consumed,” reads China’s proposal.
China claims that sludge levels can vary significantly depending on the quality of the fuel oil, the type of operation, and other factors.
A study conducted on 13 international ships revealed that oil sludge content ranged from 0.39% to 2.26%, with the potential for higher levels due to the poor quality of some blended fuels.
Improving Accuracy of CII Ratings
China believes that since determining an exact sludge percentage is difficult, it is better to establish an “upper limit.” The country argues that by doing so, errors in fuel consumption data during the data collection process can be minimized, which will lead to more accurate CII ratings.
The annual fuel oil consumption is a critical factor in calculating a vessel’s CII, which measures carbon emission intensity over time. Setting a sludge limit would ensure that fuel consumption data is corrected, making the CII rating more accurate.
Impact of High TSP Levels on Fuel Systems
While sludge content in fuel oil is not directly regulated, it is indirectly controlled through the Total Sediment Potential (TSP) parameter.
The ISO 8217 2017 standard sets the maximum TSP content at 0.10% for marine residual fuels, as higher TSP levels can cause sludge buildup in fuel systems, potentially damaging engines.
China’s proposal will be discussed at the IMO’s Marine Environmental Protection Committee (MEPC 82) meeting, which will be held in London from September 30 to October 4, 2024. This discussion could lead to changes in how fuel oil sludge is accounted for in CII calculations.
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Source: Engine
