Last reviewed 24 April 2018
A recent news item, Commission fuels tension with the UK, told of a warning issued to the UK Government by the European Commission that it may face an appearance in the EU Court of Justice. The UK is not alone in this, being just one of 10 Member States given the same warning — for failing to transpose Directive 2015/652/EU into national law. This directive establishes a mechanism for calculating and reporting the greenhouse gas (GHG) emissions of fuels and other non-biological energy sources. This process is in support of the EU Fuel Quality Directive (98/70/EC) which aims to reduce GHG intensity of fuels by at least 6% and the Renewable Energy Directive (2009/28/EC) which mandates that at least 10% of energy consumed by road transport shall be from renewable sources before the end of 2020 through the use of biofuels. Importantly, it is only the calculating and reporting mechanism that has not been established, the biofuels required by the Fuel Quality Directive are already in use. Richard Smith looks at some potential consequences that operators need to take into account and advises on what they should do to minimise the impact on their businesses.
What are biofuels?
Biofuels are liquid or gaseous transport fuels made from plant material that can be grown, harvested and processed over a short time frame and known as biomass. The theory is that during their lifetime, these plants absorb sufficient quantities of carbon dioxide (CO2) to offset at least a large part of the CO2 emitted from road vehicle exhausts. This absorption/creation cycle takes place over a very short timescale, meaning that CO2 in the atmosphere is effectively reduced and is in contrast to fossil fuels, which absorbed CO2 millions of years ago but are now producing a net increase. Energy obtained from such fuels is commonly known as “renewable” energy, though semantically such a concept is impossible and violates the laws of physics.
Road transport fuels
Gaseous fuels in the form of compressed natural gas (CNG) are being used and do not pose any particular problems in use. The concern is with liquid fuels, petrol and diesel, that have had bio-content added.
Both petrol and diesel fuel available at the pump now contain a certain amount of bio-product. The UK regular unleaded petrol may contain up to 5% ethanol routinely and, since March 2013, as much as 10%. Where the proportion of ethanol is over 5%, the pump must be labelled as “unleaded petrol 95 E10” but no specific labelling is required as long as the proportion does not exceed 5%. Significant numbers of vehicles are incompatible with E10 fuel and the UK Government has discouraged an early switch to it for that reason. It is, however, commonly available in France where the pump is labelled “SP95-E10”. An occasional fill-up with E10 may be acceptable but it should not be used for prolonged periods unless the manufacturer has certified the vehicle as E10-compatible.
The biomass content of diesel fuel varies between 2% and 20%, with the actual percentage being indicated as “B2”, “B5”, “B10” or “B20”, the number indicating the percentage bio-content. Like petrol engines, modern diesel engines can usually cope with small percentages of bio-content, up to the 7% in ordinary pump fuel, but the use of blends above that is discouraged by manufacturers, who advise special precautions if the use of B10 or B20 is unavoidable.
Problems with biofuels
Bio-ethanol and bio-diesel have many adverse features in common. They do reduce carbon monoxide and hydrocarbon emissions, but modern emission control technology has rendered those mostly insignificant anyway. Bio-diesel also reduces particulate emissions but increases emissions of nitrogen oxides — the cause of much current concern. Both help give better combustion, but their energy density is significantly lower than non-bio versions, so fuel consumption will be increased.
Both fuels have a highly solvent effect that may cause problems with corrosion of metals such as aluminium, zinc, brass, copper and lead/tin coated steels, all commonly used in fuel systems, and dissolve or swell rubber seals and gaskets. High bio-content fuels may also dislodge sediments in older tanks and fuel lines, leading to fuel blockages.
Both bio-ethanol and bio-diesel attract water from the atmosphere, particularly in storage, and much more so at higher levels, leading to problems with corrosion and separation of the fuel and water layers. With bio-ethanol, the water collects at the bottom of the tank — the very level from which the fuel is drawn — causing engine misfiring and rough running. With bio-diesel, in the presence of oxygen (ie under normal storage conditions) bacteria form at the interface between the fuel and the water and can form sludge at the bottom of the tank, blocking fuel lines and filters. Bio-diesel drawn from continually replenished supplies and used quickly will not usually cause problems but where operators hold bio-diesel in their own tanks for prolonged periods, this bacterial growth may well occur and special precautions will be needed to prevent it.
Bio-ethanol has higher volatility than normal petrol and that increases evaporation of hydrocarbons into the atmosphere and makes the possibility of “vapour lock” more likely. Vapour lock is where the liquid fuel vapourises somewhere in the fuel supply system owing to high local temperatures and therefore does not flow to the engine.
Cold weather problems with normal diesel fuel are well known and bio-diesel is no different, in fact it may be worse. At low ambient temperatures, waxes in the fuel solidify and will block fuel lines and filters, causing fuel starvation and engine shutdown. This will be a particular problem on short runs and whenever it occurs will require special attention to bleed the fuel system even after the wax has melted. Bio-diesel may exacerbate this waxing, depending on the source of the bio-content. Two common sources are rapeseed oil and palm oil and while rapeseed oil is liquid at 0°C, palm oil is solid. Fuel refiners have always supplied special “winter diesel” during the colder months and it is now even more important to ensure the correct fuel is used at that time of year.
Operators who hold their own stocks of fuel must ensure that they run down the tank level in the autumn and restock with appropriate fuel.
Biofuel and the global environment
Not only does the increase in biofuel use cause problems for operators but it is now increasingly being shown to be more harmful to the global environment than previously believed as well.
The basis for the encouragement of the use of biofuels that they are carbon-neutral, is based on an assumption that the CO2 released by the burning fuel is offset by the CO2 absorbed during growth of the plants used to produce the fuel. However, empirical studies not based on the assumption of carbon neutrality have shown that rising use of biofuels is actually associated with a net increase, not decrease, in CO2. The increased fuel consumption also adds to the CO2 produced. This calls into question the accuracy of current carbon footprint calculation models, which are the basis for policy development.
There is also widespread concern about the cultivation of the crops necessary to provide the bio-content. When many parts of the world struggle to feed people now, is it wise to switch acreage from production of food to production of fuel? If extra land is brought under cultivation to grow biofuel stocks the concern is that it will destroy delicate ecosystems and habitat and lead to a fall in biodiversity. It was recently announced that Iceland will ban the use of palm oil in its own-brand products for this reason, though the Renewable Energy Directive from the EU does require that biofuels shall not come from raw material obtained from such land.
What should operators do?
Operators should take certain precautions to minimise the impact on their businesses:
find out what blend of bio-diesel is recommended by the manufacturers of the vehicles in their fleet and use only that blend
ensure that vehicle fuel tanks are regularly run down to nearly empty and then filled with fresh fuel
where the use of bio-diesel blends higher than recommended is unavoidable:
check the engine oil level frequently; if an increase in level is noted, contact an authorised service agent for the manufacturer
keep strictly to the manufacturer’s recommended service intervals
if the vehicle is not going to be used for several weeks, fill the tank with ultra-low sulphur (or sulfur) diesel (ULSD) to ASTM D975 ULSD standard
if fuel is stored in bulk tanks:
ensure fuel is not stored for more than six months
maintain tank level as full as possible with minimum air space
replenish with winter/summer diesel as appropriate
tightly seal the tank to prevent any moisture ingress
site tank out of direct sunlight or insulate tank
do not store in tanks with any zinc or copper content — ideally use plastic.