Marine bunker fuel quality – 2020: a year in review | ExxonMobil Marine

Steve Bee

Marine bunker fuel quality – 2020: a year in review

Steve Bee, VPS Group Commercial & Business Development Director

In the run-up to IMO 2020, shipping companies were faced with the conundrum of identifying the fuel that best suited their business needs: MGO, HSFO in combination with scrubbers or the new VLSFOs that were coming into the market. The global shipping fleet quickly provided their answer – VLSFO fuels accounted for 66% of all samples received by VPS in 2020.

The predicted rise in demand for MGO never materialised; it accounted for only 14% of the samples sent to VPS during the year. HSFO, which historically accounted for 85% of all test samples, saw demand plummet to only 15% in January 2020. That number grew to 18% by the end of the year, indicating an increased use of scrubbers.

VLSFOs were expected to arrive with a wide range in viscosities and densities, high Cat Fines and stability and cold-flow issues due to their high paraffinic content. That proved largely to be the case although by the end of 2020, 85% of VLSFOs we tested had a density of between 920-980kg/m3. Around 85% had a viscosity lower than 180Cst although across the year, 50% of VLSFO viscosities were actually <80Cst.

A major issue has been with fuel stability. On many occasions, the fuel has met specification but within weeks has destabilised and formed sludge. The ‘shelf-life’ of VLSFOs is generally less than three months, which is far less than HSFO (six months) and MGO (12 months). The complex blends of residual and paraffinic content has led to a conflicting situation where VLSFOs require heating to avoid wax precipitating from the paraffinic content, but extended heating at higher temperatures speeds up the fuel aging process and has a destabilising effect on the residual components.

The average wax appearance temperature (WAT) of VLSFOs was 20°C above the average pour point. This would suggest that in many situations the historical advice of storing fuel at 10°C above the pour point is no longer a safe recommendation. Wax may have already precipitated from the fuel at temperatures that are higher than more than 10°C above the pour point.

The key reason for VLSFOs being developed was to ensure compliance with the 0.50% sulphur global cap limit. However, on average 3.1% of samples tested were non-compliant in 2020. Sulphur also accounting for 45% of all VLSFO off-specification tests.

One piece of good news is that the cat fine content of VLSFOs has been lower than expected; in January 2020 test levels ranged from 2ppm-500ppm, with 22% having cat fines greater than 40ppm. However, this decreased throughout the year and now the range is 2-200ppm, with just 11% having a cat fine level greater than 40ppm.

Across 2020, 6.3% of all tested VLSFOs exceeded at least one test parameter specification, with ironically, sulphur being by far the largest culprit. Europe accounted for the highest percentage of off-specifications samples, with 12% exceeding at least one test parameter specification.

2020 has shown bunker fuel quality continues to be a concern, with the new VLSFOs requiring additional fuel management. The outlook for 2021 remains unclear but VPS will remain vigilant on your behalf.

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