Non-Subscriber Extract
UK biodiesel study fuels debate on the practicalities for naval vessels
By Richard Scott
12 May 2008
A study carried out by UK naval architecture and systems engineering group BMT Defence Services has identified a range of issues associated with the potential use of biodiesel fuels aboard warships.
The study activity has examined how biodiesel, when mixed with standard UK naval fuel - F76 - and other low-sulphur fuels, may affect the quality of fuel produced. This in turn has ramifications for the safe and reliable operation of engines.
The study draws on research performed by the company under its own 'technology watch' programme, together with work undertaken by Royal Navy (RN) Lieutenant Roy Casson for a Master of Science project.
John Buckingham, BMT Defence Services' chief mechanical engineer, elaborated further in a paper to the IMarEST INEC 2008 naval engineering conference in Hamburg on 2 April 2008.
He said that while there is a continuing requirement for the world's navies to seek to meet International Maritime Organisation and other local emissions requirements, there is also "a pressing need to be able to operate worldwide in an economy where fossil-based distillate fuels may become scarcer and increasingly mixed with fuels that are synthetic or derived from biomass. In the near term the most common of these is likely to be biodiesel".
According to Buckingham, the central problem is that the specification of the fuel will be altered by the type of biodiesel used and the degree to which it is mixed with other fuel. "The naval distillate F76 to Def-Stan 91-4 is the datum designated fuel for UK RN ships' machinery. The set of specific performance in this standard allows for latitude in fuel specification to reflect the variation in fossil fuel supplies," he said.
If F76 is unavailable, NATO warships are permitted to take on Marine Gas Oil (MGO) to Distillate Marine Grade A as an emergency substitute fuel from designated suppliers worldwide. Such fuels, while still distillate, may contain additional trace element quantities that may affect gas turbine engine operations.
If this too is unavailable, then the next best permissible sources, as recommended by the UK Ministry of Defence (MoD), may be automotive Ultra Low Sulphur Diesel (ULSD), equivalent to BS EN 590 or equivalent. EN 590 may contain up to 5 per cent biodiesel to meet environmental legislation.
According to Buckingham, given the worldwide operating profile of UK warships and auxiliaries, "any changes to the fuel infrastructure at ports needs to be considered early so that the necessary changes to onboard machinery and operations can be identified and their impacts assessed".