conventional fuels are essentially mixtures of mineral oil based hydrocarbons and noxious liquid substances. At present, the International Maritime Organization (IMO) Bulk Liquids and Gases sub-committee are addressing the issue of how to classify the blends. In the interim, provisional measures are in place which state that blends of conventional fossil fuels and biofuels in which the proportion of biofuel component is less than 15% should be carried under the provisions of MARPOL Annex I. Blends with a proportion of biofuel component greater than 15% would have required the shipper in question to contact an administrator for a decision on how the product should be carried. These measures were to remain in place until July 2009 but have recently been extended until July 2011 and have been developed to take the form of a 3-band system as follows:
Band 1: 85% or more petroleum oil (15% or less FAME) – Product is carried as an Annex I cargo. Oil discharge monitoring equipment (ODME) should be approved/certified for the mixture carried or tank residues and all tank washings should be pumped ashore.
Band 2: More than 1% but less than 85% petroleum oil (15% to 99% FAME) – Product carried as an Annex II cargo. Blend is treated as tripartite mixture in line with MEPC.1/Circ.512 but ship type cannot be lower specification than any component in the blend; or
Cargo treated as pollution category X, ship type 2 with worst case minimum carriage requirements assigned (based on analogous products in the IBC Code such as pyrolysis gasoline, butyl benzene or the generic entry for n.o.s. (4) products)
Band 3: 1% or less petroleum oil (Greater than 99% FAME) – Product carried as Annex II cargo and cargo treated as the Annex II product contained in the blend. Issues of concern include the potential effect that FAME and ethanol cargoes might have on ODME equipment – it is understood that further testing is needed to clarify this issue. The varying blend levels also impact upon how the cargo is measured – work is currently being undertaken on samples of FAME from various origins and at different blend levels to establish suitable volume correction factors (VCFs) to be used in cargo measurement.
Future developments
Up to this point, discussion has been limited to FAME and bioethanol, the so called ‘first-generation’ biofuels. The Renewable Energy Directive was updated in December 2008 to include sustainability criteria for
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biofuels, amid worries that the biofuels currently in production were not being produced in a sustainable manner. In order to meet the various legislative targets, not only will the volumes of biofuels used need to increase, but technology will need to be developed and made commercially viable to bring new, sustainable biofuels onto the market. Examples of such biofuels include; biodiesel produced from algal oil, biodiesel produced from the crop jatropha (which does not compete with food crops for land), bio-butanol (which is a slightly longer chain alcohol than ethanol) produced from renewable sources of biomass, and ‘renewable diesel’, a synthetic diesel which would meet the EN590 diesel standard, produced by the catalytic hydrogenation of vegetable oils.
Conclusions
It is clear that the integration of biofuels and blends of biofuels with conventional fuels into our current fuel infrastructure has raised a number of issues, many of which were unforeseen and have only come to light after the introduction of the fuels. The majority of the problems concern FAME, both as a neat product and as a blend with petroleum diesel. The variety in the feedstock which can be used to produce FAME can impart very different properties on the FAME produced. In Europe there is currently only a single FAME standard, and the particular type of FAME, and therefore the properties the material may be expected to display, may not always be clear from the shipping documents.
The major issues for consideration for those involved in shipping FAME are the high potential for water contamination and associated problems with microbiological spoilage, and, whilst a 5 ppm limit remains in the DEFSTAN 91-91 jet fuel specification, the potential for contamination of jet fuel cargos by traces of FAME. Additionally, the relative instability and sensitivity of the material to low temperatures and trace metals require extra care in terms of how the product is handled. Bioethanol and gasoline blends are also sensitive to water contamination with the potential for irreversible phase separation to occur if the level of water passes a certain threshold level.
Of course, it is possible that as blend levels increase, new and unforeseen problems will arise that will require further research and new approaches to our way of dealing with these materials. It is likely that biofuels will continue to provide a very real challenge to all those involved in their production and distribution over the coming years, and a knowledge of the often quite unique properties that these products display will be very beneficial for those wanting to minimise the risk of facing unwanted claims.
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