Dyson: testing concerns. Image credit/CD, Exponent.
Blending fuel will be the way the bunker industry meets new demand for low sulfur material once the 0.5% sulfur cap comes into force from the start of next year.
However, blended product carries its own set of issues not least, according to marine consultant Chris Dyson, being the reliability of testing methods to determine the quality of blended fuel.
"The potential impact on fuel quality has been reported regularly, but the challenge for fuel testing itself is less conspicuous," Dyson said in marine engineering publication Marine Propulsion.
While accepting the need to quality test blended fuels, Dyson believes "current tests are limited in their ability to predict the performance of fuels in service".
In pointing to "the deposition of sludge" which is a "slow process that takes days, weeks, or months", a testing laboratory might rely on artificially severe conditions to achieve a viable result.
But according to Dyson, one common stability testing method (called Turbiscan) to test beyond ISO 8217 parameters "does not capture long-term destabilisation, which can occur days (or longer) after blending is performed".
In an interview with Ship and Bunker earlier this year, Dyson said that the lack of information on the performance of low sulfur fuels would suggest that ship operators maintaining vigilance on fuel testing and sticking with established practices, such as fuel tank segregation, may well avoid the worst problems.
Dyson is with engineering consulting firm Exponent.