ExxonMobil Issues "Top-Tips" to Save on Bunker Costs

ExxonMobil says vessel operators can save up to $3 per metric tonne on their bunker costs by optimising quality.

Vessel operators could save up to $3 per metric tonne (pmt) on their bunker costs by optimising quality, according to ExxonMobil Marine Fuels & Lubricants, who has issued five "top-tips" that it says can help vessel owners and operators achieve the best value when purchasing marine fuel.

The supplier says it is advising marine operators to consider the following five fuel quality factors:

Water content

ISO 8217:2012 permitted water content compliance level is 0.5%, while ExxonMobil's marine fuel has an average of only 0.12%.[iii]

If marine fuel is supplied at the 0.5% compliance level this could potentially cost US$6,000 [ii] per purchase for a 2000mt stem, and the water should be removed prior to burning.

Water removed from marine fuel prior to use may then add a further disposal cost of up to US$3,000[iv]. 

Additional maintenance costs may also be incurred to remove resulting sludge from the purification systems.

Metal content

Aluminium and Silicon in marine fuels, known as catalytic fines, have the potential to cause significant engine damage. 

This could lead to substantial repair costs and potential vessel delays. ISO 8217:2012 and ISO 8217:2005 allow for levels of catalytic fines up to 60mg/kg and 80mg/kg respectively.

Major engine builders typically recommend the level of catalytic fines should be less than 15mg/kg at the engine inlet. 

ExxonMobil's marine fuels normally have significantly lower levels of catalytic fines, with an average of 10mg/kg5.

These low levels help limit catalytic fine removal efforts, reduce abrasive wear on critical engine components and potentially avoid the cost of additional maintenance and possible breakdowns.

Marine fuel stability

To help meet the lower sulphur levels specified in changing marine industry regulations, there may be a tendency to blend marine fuel from a variety of different sources which may cause the resultant blend to become incompatible.

Unstable fuels have the potential to cause sludge or heavy deposits to build up which may prove costly to resolve and may impede vessel performance. 

ExxonMobil's marine fuels arrive from an integrated supply chain and are tested to strict standards before they leave the refinery or terminal, with systematic quality control throughout the supply chain.

Calculated Carbon Aromaticity Index (CCAI) level

CCAI level is the indicator of marine fuel combustion quality and it's important that it is neither too high nor too low. 

Poor quality marine fuel with an inappropriate CCAI level, caused by incompatible blend components, could cause poor combustion and has the potential to impact vessel performance. 

ISO 8217:2012 states a max limit of 870 for most common residual marine fuel grades and ExxonMobil's marine fuels sit within the working parameters of major engine manufacturers, helping to protect against poor performance.

Laboratory analysis

Finally, ExxonMobil recommends that it is best practice to send fuel samples to an approved laboratory for analysis.  This allows operators to understand the quality of the marine fuel received and how to manage the marine fuel system on board their vessels.

[i] The purchase cost of water in the tank at the 0.5% water level, based on a fuel cost of US$600/mt, is the equivalent of US$3/mt.
[ii] A 0.5% water level would amount to 10mt per 2,000mt fuel delivery.  Based on a fuel cost of US$600/mt, this is the equivalent of US$6,000
[iii] Source: DNVPS, 2013 ExxonMobil Singapore Average.
[iv] Estimated sludge/slops removal cost in Singapore
[v] Source: DNVPS, 2013 ExxonMobil Singapore Average