BIOFUELS – Issues For Boat Owners.
I came across this excellent article in the Boat Owners Association Newsletter. It explains a lot of what we discussed last year. Following my own problems, can I suggest if you go BIO, do frequent fuel drains to try and get rid of the GUNK before it causes a stoppage and also try to stay with one type of fuel or the other. More recently we have become more aware of storage problems with Biofuels. The lighter Ethanol evaporates off leaving a lower quality fuel. Biofuels should be used in 30 days, okay for cars but questionable in boats and aircraft.
Geoff Raebel
A number of articles have appeared in boating magazines over the last year or so that draw attention to problems that can be encountered when switching from pure petroleum fuels (petrol or diesel) to petroleum fuels blended with biofuels. Some of these problems have concerned catastrophic damage to engines, fuel tanks and fuel systems. In the United States it has even involved multi million dollar class action law suits against US oil companies on behalf of US boat owners. To put this into perspective, the following may be of interest.
Some Background: Petroleum fuels are those fuels derived solely from the processing of hydrocarbons (fossilised organic matter) extracted through drilling (liquid crude) or open cut mining (oil bearing sand or shale). Processing of the extracted oil produces a whole range of different fuels including petrol and diesel. From a greenhouse perspective, the processing and burning of hydrocarbons involves the release of previously locked up carbon into the atmosphere – negatively impacting on the environment. Biofuels, on the other hand, are those fuels typically derived from the processing of renewable biological material sourced from the production of agrofuel crops such as sugar-cane, soybeans, corn, canola, palm oil, rapeseed oil and jatropha and also, in the case of biodiesel, recycled cooking oils and animal fat. And for the reason that the process of growing the biological material absorbs as much carbon as it produces during combustion, biofuels derived from this process are seen to be carbon neutral. Ethanol and biodiesel are biofuels that are, respectively, near substitutes for petrol and diesel. The initial use of biofuels was as an additive (ethanol added to petrol and biodiesel added to diesel) to replace some of the components of petrol and diesel that had to be significantly reduced or taken out altogether to meet tighter US and European environment standards – methyl tertiary butyl ether (MTBE) used in petrol to improve combustion and reduce air pollution which was found to contaminate ground water in the US and the sulphur in diesel which was found to significantly contribute to air pollution. But with the recognition that the price of petroleum will, over the longer term, continue to rise and biofuels are carbon neutral, the use of blended fuels will become more widespread.
The addition of ethanol into petrol, as did the addition of MTBE until it was banned, serves as an oxygenate to improve fuel combustion and, as a consequence, reduce air pollution. But for the reason that ethanol contains about 34% less energy by volume than petrol, its blending with petrol will reduce efficiency. An E10 (10% ethanol and 90% petrol) blend will, after taking into account the higher octane rating of ethanol, result in a net loss of efficiency of about 3%. The addition of biodiesel into diesel serves to restore to the diesel its vital lubrication qualities lost as a consequence of the mandatory removal of sulphur. Biodiesel contains about 8% less energy by volume than diesel and so a B10 (10% biodiesel and 90% diesel) blend will result in a net loss of efficiency of about 1%.
In what proportion the biofuels are added to petroleum fuels varies and in most instances is determined by a combination of economics and local legislation. To determine what the proportions are, fuels on sale are appropriately labelled using a common system. The letter E or B denotes, respectively, ethanol blended petrol or biodiesel blended diesel. The number following the letter denotes the percentage of the blend. E10, for example, is petrol containing 10% ethanol and B20 is diesel containing 20% biodiesel. In Australia right now, legislation provides that the ethanol content of petrol cannot exceed 10%. In most states, ethanol blended petrol is sold as E5 or E10. No legislation however exists for limiting the content of biodiesel in diesel. The most common biodiesel blended diesel however is sold as B20. Some fuel outlets, however, also sell 100% biodiesel marketed as B100.
Issues Concerning Ethanol Blended Petrol: Although ethanol may solve a number of environmental issues, two of its characteristics can cause problems for boat owners – it is an excellent solvent and it is hygroscopic.
Because ethanol is a solvent it has the ability to do an excellent job of cleaning out the entire fuel system. For older engines, it cleans out all the muck in the bottom of the tank and any residue stuck in fuel lines and fuel filters. The problem is that ultimately this soup finds its way into the filters, carburettor or fuel injectors – at which point the engine stops. But in addition to it giving the fuel system a good clean out, ethanol can also cause damage to various components – permeation of rubber fuel lines, destruction of plastic and certain metal components and, particularly as it might concern older vessels, the destruction of fibreglass fuel tanks.
Its hygroscopic characteristics mean that ethanol has a very high affinity for water. Put simply, it absorbs moisture. This is not a problem in the sealed fuel system of a motor car but, for the reason that most boats have their fuel tanks open to the humid air, ethanol sucks water into the tank. In time, that water will separate from the fuel as a non-combustible layer of liquid in the bottom of the tank which will stop most engines. The intermittent use of boats (as opposed to motor cars) obviously exacerbates this feature because it gives greater time for these non-combustible liquids to form.
In April this year, an article in Powerboat-World drew attention to the reality of these concerns. In the Long Island Sound area there were a number of instances where engines were badly damaged when fibreglass tanks that had been filled with ethanol blended fuel started to fail. Some of the tanks had begun leaking. Similar reports came from California and the Great Lakes area. Tests, conducted on the problems with fibreglass tanks exposed to the blended fuel, indicated that some tanks lost as much as 40% of their structural strength. One boater in California, a 50 year old attorney, discovered that the use of ethanol blended fuel in his boat had caused damage to his fibreglass tanks costing US35,000 to repair. He has now filed a law suit in the Federal court against a number of oil companies, including Chevron and Exxon Mobil, and a number of distributors.
In April of last year (2007), Boats.Com, an online marine industry advertiser, also wrote a sobering article on the use of ethanol blended fuels. Amongst a number of issues raised, was the very common complaint about gummed up fuel systems – fuel systems that had only been sitting idle for as little as 10 days. Engine dealers in a number of locations contacted by Boats.Com were recommending to their clients that each time they finished with their boat (and expected to be away for more than a week or two) they should drain the carburettor floats of any fuel. Good advice but perhaps it should also extend to draining the tank!
Issues Concerning Biodiesel Blended Diesel: As for ethanol, there are two characteristics that biodiesel exhibit that boat owners should take into account – it is more of a solvent (albeit much less so than ethanol) and it is hygroscopic.
Methanol used as a catalyst in the production of biodiesel, will loosen accumulated sediment in tanks and fuel lines and push them through to the primary filters. This in itself won’t destroy anything but it will require that filters be checked and/or changed at regular intervals until the fuel system has been cleaned out. Failure to do so can cause fuel starvation and engine shut down. And although the fuel is not likely to inflict the same kind of damage to older fibreglass tanks as in the case of ethanol, there are a number components in an engine that might suffer from its use. Particularly in the case of blends higher than B20, biodiesel can cause problems with natural rubber – seals and hoses in the fuel system in particular will be vulnerable to damage and should therefore be changed. Biodiesel is also not compatible with some metals such as brass, bronze, copper, lead tin, and zinc. Some engine manufacturers also caution users about potential problems concerning engine lubricating oil. If biodiesel is mixed with the lubricating oil it will react with the oil to produce a sludge in the sump that could block oil passages and damage the engine itself. The more frequent changing of oil and oil filters may offset this as an issue.
Because biodiesel is hygroscopic, it will absorb water. In that regard it is more susceptible to water contamination than straight diesel. Water in diesel can promote the corrosion of the fuel system and the growth of microorganisms that can block the fuel system. But management of this feature is within reason and not too much different from how the fuel would already be managed. In any event there are products available that can be used to dry fuel and clean up biological contaminants.
Unlike the use of ethanol, catastrophic damage from the use of biodiesel seems to have fewer colourful examples to write about. But particularly where it used in engines manufactured prior to 1997, it will be prudent to conduct a compatibility audit on all components in the system – rubber components including hoses, gaskets and seals and the cleanliness and appropriateness of the fuel tank.
Summary: For the reason that biofuels make a positive contribution to the mitigation of a number of issues concerning the burning of petroleum fuels, it follows that its availability will not only become more widespread but its sale on a blended basis may become mandatory – underpinned by legislation designed to respond to both political and scientific imperatives. This is already occurring in Europe, the US and Asia. As it concerns motor vehicles, this is not such an issue. Most vehicles built after 1986 use components that are compatible with the new fuels. And issues concerning water absorption are irrelevant because the contents of the tanks are regularly cycled. But for boats, the use of biofuels can be more problematic – as described above. To that end, the best near term strategy might be to avoid using biofuels altogether but, at the same time, seek technical guidance on what needs to be modified or replaced in the engine and its fuel system should the day come when that is all there is available.
Reproduced with permission from the Boat Owners Association of NSW www.boaters.org.au