Biofuel FAQ

What is Biofuel?
Biofuel bi-o-fu-el (noun) is fuel made from biological materials:  a renewable fuel that is derived from biological matter, e.g. biodiesel, bioethanol, biogas and methane.


What is Biodiesel?
Biodiesel is the name of a clean burning alternative fuel, produced from domestic and renewable resources such as vegetable oils. Biodiesel does not contains any petroleum, but can be blended at any level with diesel to create a biodiesel blend. Biofuel can be used in compression-ignition (diesel) engines with no major internal modifications. Biodiesel is clean, simple to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics.

Advantages of Biodiesel
Biodiesel is a CO2 (carbon) neutral alternative to diesel and fuel oil, and may reduce our dependence on fossil fuels. Many studies have also indicated that auto particle pollution is massively reduced with the use of biodiesel fuel, this is why it is used in urban buses in a number of large towns and cities, including Graz in Austria. Biodiesel also provides a cleaner combustion and act as lubricant for the engine, where it can replace the standard additives. In the event of environmental spill, biodiesel also breaks down faster and also reduces the risk of pollution from residential oil tanks. Biodiesel can however result in an increase in the emission of nitrogen oxides. The future uses of biodiesel should be considered in conjunction with various filter systems that are designed to reduce the amount of hazardous and toxic materials in car exhaust fumes.

Biodiesel Blends

Biodiesel is produced in three main blends: B5, the five per cent mix with normal diesel, B30, the 30 per cent mix, and B100, which is pure biodiesel, containing no added diesel. B5 is already retailed on many station forecourts throughout the UK, but B30 is a more specialist fuel and is not as widely available. Whichever blend, the biodiesel should meet the standards of BS14214.

Common Biodiesel / Diesel Terms
SVO – straight vegetable oil used as diesel fuel (this is usually new oil, fresh, uncooked)
PPO – pure plant oils, same as SVO: PPO is the term most often used in Europe
SVO – waste vegetable oil (used cooking oil, “grease”, fryer oil, probably including animal fats or fish oils from the cooking)
UCO – used cooking oil (what we called it in the first place until everyone started calling it WVO, even if it wasn’t necessarily all vegetable)
IDI – Indirect Injection diesel engines: the fuel is injected into a pre-chamber or swirl-chamber before going on to the combustion chamber. Pre-chamber engines are more tolerant of SVO than swirl-chamber engines.
DI – Direct Injection diesel engines: the fuel is injected straight into the combustion chamber. DI diesels are less tolerant of SVO than IDI engines
Types of DI diesels:TDI – Turbo Direct Injection / CDI or CRD – Common-rail Direct Injection / PDI or PD – Pumpe Düse Unit Injection (Direct Injection, each injector has its own pump)

Does biodiesel crontribute to “global warming”?
A 1998 biodiesel lifecycle study, jointly sponsored by the US Department of Energy and the US Department of Agriculture, concluded biodiesel reduces net CO2 emissions by 78 percent compared to petroleum diesel. This is due to biodiesel’s closed carbon cycle. The CO2 released into the atmosphere when biodiesel is burned is recycled by growing plants, which are later processed into fuel.

How is Biodiesel produced?
Biodiesel is produced from fats or oils using a process known as transesterification. Biodiesels chemical name is “fatty acid methyl (or ethyl) ester ( FAME )”. These oils are mixed with sodium hydroxide and methanol (or ethanol) and the resulting chemical reaction produces biodiesel and glycerol. 1 part glycerol is produced for every 10 parts of biodiesel.

Is Biodiesel the same thing as raw vegetable oil?
WRONG! Biodiesel is produced from any fat or oil such as soybean oil, this is a refinery process called transesterification . Transesterification is a reaction of the oil with an alcohol to remove the glycerin, which is a by-product of biodiesel production.

Biodiesel is defined as mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats. Biodiesel refers to the pure fuel before blending with diesel fuel. Biodiesel blends are denoted as, “BXX” with “XX” representing the percentage of biodiesel contained in the blend (ie: B20 is 20% biodiesel, 80% petroleum diesel).

Is biodiesel used as a pure fuel or is it blended with diesel?
Biodiesel can be used as a pure fuel or blended with petrol in any percentage mix. The term B20 (blend of 20 percent by volume biodiesel with 80 percent by volume diesel) has shown significant environmental benefits combined with a minimal increase in cost.

Is Biodiesel safe to use?
Biodiesel is actually one of the most thoroughly tested alternative and renewable fuels on the market. A number of independent studies have been completed with results showing that biodiesel performs very similar to petroleum diesel and benefits the environment when compared to diesel. Biodiesel is also the first and only alternative fuel to have completed the rigorous Health Effects testing requirements of the Clean Air Act. Biodiesel has been proven to perform similarly to petroleum diesel in more 60 million successful road miles and in virtually all types of diesel engines, countless off-roading miles, and marine hours.

Can I use Biodiesel in my Common Rail Engine?
There is something in the warning about the use of biodiesel in a common rail diesel engine, but this is not what the engine manufacturers would have the public believe. In a common rail diesel engine the fuel can be exposed to higher working temperatures and more recirculation than otherwise. The fuel that is in the injection rail gets up to 100°C and most of this does not get injected, but recirculated back to the fuel tank, where the fuel has the chance to be exposed to air again and again. This increases the chance that the biodiesel may oxidise. Now, biodiesel that meets current specifications and standards will have a very high oxidation stability. This means that it takes a longer time before it can go bad. In a common rail system the speed that oxidation can occur is increased and the time at which it can resist is decreased. This is not normally a concern if your biodiesel meets correct spec, if not, then it could be an issue – a very expensive isssue!.

How do biodiesel emissions compare to petroleum diesel?
When used in a conventional diesel engine, running Biodiesel shows a substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter compared to emissions from Petroleum diesel fuel. In addition to this the exhaust gases of sulfur oxides and sulfates are essentially eliminated compared to diesel.

Of the major exhaust pollutants, both unburned hydrocarbons and nitrogen oxides are ozone or smog forming precursors. The use of biodiesel results in a substantial reduction of unburned hydrocarbons. The Emissions of nitrogen oxides are either slightly reduced or slightly increased depending on the duty cycle of the engine and testing methods used. The overall ozone forming potential of the speciated hydrocarbon emissions from biodiesel was nearly 50 percent less than that measured for diesel fuel.

Will I get as much power from my engine with biodiesel?
Biodiesel contains 5 – 8 percent less energy per gallon than petroleum diesel fuel. However Blended fuels for example B20 obviously will have less of an energy loss. Some studies have indicated that other factors such as more efficient burning and better injection efficiency due to higher viscosities (or thinkness) actually may counteract this energy loss. In any event some users of Biodiesel might experience a slight power loss.

Can I use biodiesel in cold weather?
Biodiesel is more susceptible to issue relating to colder temperatures than petroleum diesel, however when blended this effect is moderated or reduced. A B20 biodiesel blend 20% Bio and 80% Petroleum Diesel has the same cold flow properties as petroleum-based diesel fuels. However, B20 will have a higher gel point this can be from 3°F to 5°F higher. The common advise is that as with Biodiesel you will need to use a kerosene blend or some other anti-gelling additive in colder temperatures.

Can I use biodiesel in my existing diesel engine?
Biodiesel can be operated in any diesel engine with little or no modification to the engine or the fuel system. It has a solvent effect that can release deposits that are accumulated on fuel tank walls and fuel pipes from previous diesel fuel storage. This release of deposits may clog fuel filters initially and therefore precautions should be taken to ensure that only Biofuel that meets the biodiesel specification (EN 590) is used in yuor diesel engine.

What effect will biodiesel have on vehicle warranty?
None, so long as the blended fuel used complies with European Standard EN 590. According to the UK Department for Transport in this blend: “It can be used just like ordinary diesel in all private and commercial vehicles – without adaptation and under vehicle warranty The main commercial vehicle manufacturers such as Volvo, MAN, Ford, Scania and Mercedes all approve biodiesel blends for use in their vehicles. This is based on the stance of the Diesel Fuel Injection Equipment Manufacturers (DFIEM) whose members include Delphi, Bosh, Siemens VDO, Denso and Stanadyne. In June 2004 DFIEM members issued a statement declaring support for the use of the B5 blend (5 per cent biodiesel to 95 per cent mineral diesel). In order to honour warranties, they insist that fuels must meet the quality standards laid down in EN 14214 and EN 590.” The level of inclusion is likely to increase to 10 per cent over the next few years.

Can I run my car on Vegitable Oil?
Vegetable oil can be used as fuel just as it is, even without being converted to biodiesel.However you must consider that straight vegetable oil (SVO) is much more viscous (thicker) than normal petroleum diesel fuel or biodiesel, and it doesn’t combust the same in the engine. Many studies have suggested that using SVO can damage some engines.

Advantages of SVO (Sunflower Vegitable Oil)
The main advantage of running straight SVO (Vegetable) is that you can buy it off the shelf and simply top up as needed. However you must consider that straight vegetable oil (SVO) is much more viscous (thicker) than normal petroleum diesel fuel or biodiesel, and it doesn’t combust the same in the engine. Many studies have suggested that using SVO can damage some engines Many people get round this buy using a heat exchange unit to heat the SVO before it enters the engine and fuel system. Heating the SVO before it enters the fuel system thins its down making it easier for the fuel pump but also easier to combust. Another factor is the fuel pump as they must work much harder to pump the fuel to the engine. There has been much discussion regarding the correct fuel pump needed but the common consensus is that Bosch fuel pumps are more than capable of this.


What is Bioethanol
The principle fuel used as a petroleum substitute is bioethanol. Bioethanol is mainly produced by the sugar fermentation process, although it can also be produced by the chemical process of reacting ethylene with steam. The main source of sugar required to produce ethanol comes from fuel or energy crops. These fuel crops are normally grown specifically for energy use and include maize, corn and wheat crops, waste straw, willow, sawdust, reed canary grass, cord grasses, jerusalem artichoke, myscanthus and sorghum plants. There is also ongoing research and development into the use of municipal solid wastes to produce ethanol fuel.

Ethanol or ethyl alcohol (C2H5OH) is a clear colourless liquid, it is also biodegradable, low in toxicity and causes little environmental pollution if spilt. Ethanol burns to produce carbon dioxide and water. Ethanol is considered a high octane fuel and thus has replaced lead as an octane enhancer in petrol. By blending ethanol with petroleum fuel we can also oxygenate the fuel mixture so it burns more completely and reduces polluting emissions. Ethanol fuel blends are widely sold in the United States of America. The most common blend of this fuel is 10 percent ethanol and 90 percent petrol (E10). Vehicle engines require no modifications to run on E10 and vehicle warranties are unaffected also. Only flexible fuel vehicles can run on up to 85 percent ethanol and 15 percent petrol blends (E85).

What are the advantages of Bioethanol
Bioethanol fuel has a number of advantages over conventional petroleum fuels. Bioethanol comes from renewable resources i.e. crops and not from a finite resource and the crops it derives from can grow well in the UK (like cereals, sugar beet and maize). Another benefit of Bioethanol over fossil fuel is greenhouse gas emissions. The road transport network accounts for 22% ( of all greenhouse gas emissions and through the use of bioethanol, some of these emissions will be reduced as the fuel crops absorb the CO2 they emit through growing. Also, blending bioethanol with petrol will help extend the life of the UK’s diminishing oil supplies and ensure greater fuel security, avoiding heavy reliance on oil producing nations. By encouraging bioethanol’s use, the rural economy would also receive a boost from growing the necessary crops. Bioethanol is also biodegradable and far less toxic that fossil fuels. By using bioethanol in some older engines it can help reduce the amount of carbon monoxide produced by the vehicle and thus improving air quality and emmisions. Another advantage of bioethanol fuel is the ease with which it can be easily integrated into the existing road transport fuel system. In quantities up to 5 percent, bioethanol fuel can be blended with conventional petroleum fuel without the need for engine modification. Bioethanol is produced using familiar methods, such as fermentation, and it can be distributed using the same petrol forecourts and transportation systems as before.

One comment on “Biofuel FAQ
  1. David says:

    Is it legal in the UK to distll fermented ethanol to produce bioethanol?

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