In 2013 and 2014, the global residual to distillate sample ratio was approximately 75/25 whereas this year the ratio has shifted to approximately 60/40. This global trend is primarily influenced by the shift in the ECAs, where on average the relative share of distillates went from 30% in 2014 to 53% in 2015.
Residual Fuels
This trend hardly has any influence on the global fuel quality of residual products delivered this year. Despite the exclusion of the 1% sulphur residual fuels, the average Al + Si content of 26 mg/kg is not significantly different than previous years. The average energy content of 40.43 MJ/kg is also in line with recent history.
For years in succession, viscosity and density have led the off-spec residuals table, and together are responsible for about two-third of all off-spec cases.
| Off spec residuals | 2015 | 2014 | 2013 |
| Viscosity @ 50°C | 59% | 44% | 44% |
| Density @ 15°C | 16% | 29% | 35% |
| Water | 7% | 6% | 6% |
| Sulphur | 3% | 5% | 5% |
| Al + Si | 5% | 4% | 3% |
| TSP | 1% | 1% | 1% |
| Pour Point | 3% | 1% | 1% |
| Others | 6% | 4% | 3% |
Distillate Fuels
Since January this year, VPS has issued 44% more bunker alerts related to distillate deliveries compared to 2014. The majority of these alerts are related to the flash point not meeting the ISO specification and International Convention for the Safety of Life at Sea (SOLAS) limit of 60°C. The energy content is consistent over the last years, 42.63 MJ/kg on average in 2015. The global average sulphur content of 0.11% is only marginally higher than the average 0.08% on distillate fuels delivered in designated ECAs.
Visual appearance, pour point and flash point have been responsible for the vast majority of off-spec distillates for many years. As arbitrary as the test may be, appearance can be indicative of instability and poor cold flow properties. Based on appearance, relevant additional analysis, for example cold filter plugging point and cloud point to assess the cold flow properties can be initiated. The results obtained from those analysis can be the basis on which appropriate measures on board can be taken to minimize or even avoid operational difficulties.
| Off spec distillates | 2015 | 2014 | 2013 |
| Appearance | 24% | 32% | 40% |
| Pour Point | 34% | 27% | 29% |
| Flash Point | 13% | 13% | 12% |
| CCI | 3% | 7% | 9% |
| MCR 10% | 5% | 3% | 2% |
| Lubricity | 2% | 2% | 3% |
| Density @ 15°C | 2% | 4% | 3% |
| Viscosity @ 40°C | 5% | 4% | 2% |
| Fatty Acid Methyl Esters (FAME) | 11% | 5% | - |
| Others | 2% | 4% | 2% |
A VPS study shows that in many cases there is a large difference – of up to 40°C in - between the pour point (PP) and cloud point (CP). This suggests the usage of cold flow improvers. A possible purpose of the use of such additives is to suppress the PP, ensuring it meets the ISO specification. A fair number of samples tested revealed a cloud point exceeding 20°C, meaning wax crystals will already start to form at room temperature.
The increasing cases of Fatty Acid Methyl Esters (FAME) not meeting specification is a signal of more frequent inclusion of bio-fuels in marine distillates. Although FAME in general has excellent ignition and combustion properties, it will increase the risk of microbiological growth and degrade cold flow properties which may cause difficulties in storing and handling in the supply chain and/or on board vessels.
New ECA Fuels
To offer the maritime industry an alternative to distillate fuels in complying with the 0.1% Sulphur ECA limit, New ECA Fuels (NEFs) were introduced late 2014. Primarily available in Europe, NEFs are in general high quality fuels, with trace amounts of elements and an average energy content of 42.40 MJ/kg. Compared to traditional distillate fuels, NEFs have a relatively high viscosity, reducing potential heat related difficulties when changing over.
| New ECA Fuel | Global average |
| Density @ 15°C | 896.6kg/m³ |
| Viscosity @ 40°C | 44 mm²/s |
| Viscosity @ 50°C | 27 mm²/s |
| TSP | 0.02% m/m |
| Al + Si | 7 mg/kg |
| Sulphur | 0.09 % m/m |
| Pour Point | 22 °C |
| Energy content | 42.40 MJ/kg |
Two characteristics that should be taken into account are the pour point and the ability to blend with other fuels. In order to avoid fuels to become solid, vessels need to be equipped with sufficient heating capacity to heat a fuel to at least 10°C above the pour point. The global average pour point for NEFs is 22°C. As always, blending of fuels should be avoided as much as possible. In the event NEFs are blended with other fuels, extra care should be taken and preferably compatibility should be verified through analysis up front.
It is assumed that the quality of NEFs will remain fairly constant. Considering this year to be a benchmark, it remains to be seen if future comparisons will prove or disprove this assumption.