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Can biodiesel be used in any vehicle? |
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Biodiesel may degrade certain types of rubber gaskets and hoses in vehicles that are not suitable for the use of biodiesel (mostly vehicles manufactured before 1992). The higher lubricity index of biodiesel compared to petrodiesel is an advantage and can increase life-time of fuel injectors. Biodiesel is a better solvent than petrodiesel and has been known to break down deposits of residues in the fuel lines of vehicles that have previously been run on petroleum. Fuel filters may become clogged with particulates if a quick transition to pure biodiesel is made, but biodiesel cleans the engine in the process. It is therefore recommended, to change the fuel filter 800 miles after switching to biodiesel. |
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Can bioethanol be used in any vehicle? |
Generally, the higher the ethanol component of a gasohol blend, the lower its suitability for standard car engines. Pure ethanol reacts with or dissolves certain rubber and plastic materials and must not be used in unmodified engines. Additionally, pure ethanol has a much higher octane rating than ordinary petrol, requiring changes to the compression ratio or spark timing to obtain maximum benefit. To change a pure-petrol-fueled car into a pure-ethanol-fueled car, larger carburetor jets (about 30-40% larger by area) are needed. Many ethanol engines also need a cold-starting system to ensure sufficient vaporization for temperatures below 13 °C to maximize combustion and minimize uncombusted nonvaporized ethanol. On the other hand, if 10 to 30% ethanol is mixed with fossil petrol, no engine modification is typically needed. Many modern cars can run on these mixtures very reliably.
The term "E85" is used for a mixture of 15% (by volume) petrol and 85% ethanol. This mixture has an octane rating of about 105. This is significantly lower than that of pure ethanol but still much higher than fossil petrol. The addition of a small amount of petrol helps conventional engines to start when using ethanol fuel under cold conditions. E85 does not always contain exactly 85% ethanol. In winter, especially in colder climates, additional petrol is added (to facilitate cold start).
An increasing number of vehicles in the world are manufactured with engines which can run on any petrol from 0% ethanol up to 85% ethanol without modification. These cares are called Flexible Fuel Vehicles (FFV). They can automatically detect the type of fuel and change the engine's behavior, principally air-to-fuel ratio and ignition timing to compensate for the different octane levels of the fuel in the engine cylinders.
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How can pure plant oils be used as fuel? |
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Pure plant oils (PPO, vegetable oil) are received i.a. from peanuts, rapseeds, sunflowers, soy beans and coconuts. Pure plant oils are not only raw materials for biodiesel production, but can also be used in native, unchanged form in specially refitted diesel engines. PPO has specific properties which makes it different from diesel. The use of PPO in combustion engines is possible only after refitting. The viscosity of PPO, particularly at low temperatures, is up to ten times higher than fossil diesel, which leads to technical challenges in winter running and when cold starting in conventional engines. Also the the flashpoint (240 °C) is significantly higher than that of fossil diesel. Vegetable oil is therefore particularly safe in storage and transport, and easy to handle. |
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How much biomass is used for energy purpose today? |
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Worldwide, biomass is the fourth largest energy resource after coal, oil, and natural gas. It is used for heating (such as wood stoves in homes and for process heat and steam in industries such as pulp and paper), cooking (especially in many parts of the developing world), transportation (fuels such as bioethanol and biodiesel) and for electric power generation. It is estimated that there are about 278 Quadrillion Btu of installed biomass capacity worldwide. |
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How must vehicles be refitted to run with pure plant oil? |
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Before unmodified vegetable oil is used as a fuel, the engine must be refitted for the fuel to correspond to the viscosity and combustion properties of the plant oils. The refitted vehicles either pre-heat the fuel and the injection systems or are equipped with a so-called “2-tank system” in which the engine is started with diesel and only changes to vegetable oil when the operating temperature has been reached. Pure plant oil should not be used in pure form or mixed with diesel in unadapted engines. The combustion properties differ too widely from those of diesel and damage to the injection systems and deposits in the engine may occur. |
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What are biofuels? |
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Biofuels are liquid fuels made of biomass for transportation purpose. Biofuels include biogas, pure plant oil, biodiesel, bioethanol, and their derivates. |
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What are energy crops? |
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Energy crops are crops that are grown for the specific purpose of producing energy (electricity or liquid fuels) from all or part of the resulting plant. Switchgrass, alfalfa, willow, poplar and eucalyptus are examples of plants that can be grown as energy crops. |
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What are second generation biofuels? |
Biodiesel and bioethanol are often referred as first generation biofuels as the technology is already in place. Second-generation biofuels are expected to be introduced on the longer term and include gas- or biomass-to-liquid (GTL, BTL) technologies. For the production of these fuels biomass or gas is processed into synthetic biodiesel. Also ethanol from cellulose is a second-generation-biofuel.
The production of synthetic fuels from biomass is a relatively new development and products are not yet available on the market. At the moment, there are only small research and pilot plants, but great hopes are already linked with the fuel designated as biomass-to-liquid, as very different raw materials can be used for its production. The range extends from waste materials, such as straw, biological wastes and wood offcuts to energyproducing plants which can be specially cultivated for fuel production and fully utilised.
The chemical properties of the hydrocarbons in BtL fuel permit efficient and complete combustion with low exhaust gas emission. In particular, the properties of the fuel can be influenced by changes in specific parameters such as the pressure, temperature and catalysts during synthesis and the subsequent treatment and can be “fine-tuned”. Synthetic fuels are therefore also known as tailored fuels.
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What are the environmental benefits of biodiesel? |
Environmental benefits in comparison to petroleum based fuels include:
· Biodiesel reduces emissions of carbon monoxide (CO) by approximately 50 % and carbon dioxide by 78 % on a net lifecycle basis because the carbon in biodiesel emissions is recycled from carbon that was already in the atmosphere, rather than being new carbon from petroleum that was sequestered in the earth's crust.
· Biodiesel contains fewer aromatic hydrocarbons: 56 % reduction of benzofluoranthene; 71 % reduction of benzopyrenes.
· It also eliminates sulfur emissions (SO2), because biodiesel does not contain sulfur.
· Biodiesel does produce more NOx emissions than petrodiesel, but these emissions can be reduced through the use of catalytic converters. The increase in NOx emissions may also be due to the higher cetane rating of biodiesel. Properly designed and tuned engines may eliminate this increase.
· Biodiesel has higher cetane rating than petrodiesel, and therefore ignites more rapidly when injected into the engine. It also has the highest energy content of any alternative fuel in its pure form (B100).
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What are the main barriers to biofuels? |
The use of biofuels is not yet fully established due to several market, production, technology and framework barriers.
The main barriers of biofuels are:
· Relatively high production costs
· Limited land availability & competition with other uses (food, animal feed, nature conservation, industrial use, forestry)
· Lack of standards and legal issues
· Usually crops are not optimized for energy purposes (low yields)
· Lack of experience on the market (maturity)
· Lack of Cooperation with petroleum sector
· Limited profitability for farmers
· Compatibility with current distribution system has to be created
· Vehicle compatibility has to be created
· Low public visibility
· Low public knowledge and awareness of biofuels
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What are the main forms of biomass? |
The are many types of biomass:
· Forest residues:wood from forest thinning operations that reduce forest fire risk.
· Agricultural residues: crop residues such as corn stover (stalks) and processing residues such as nut hulls.
· Pulp and paper operation residues: the byproducts of logging and processing operations.
· Urban wood waste: lawn and tree trimmings, wood pallets, construction and demolition wastes.
· Animal waste: cattle, chicken and pig waste converted to gas or burned directly for heat and power.
· Landfill gas: the natural byproduct of bacterial digestion of organic garbage.
· Energy crops: trees or herbaceous biomass grown specifically for energy.
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What is biodiesel? |
Biodiesel is a biodegradable transportation fuel for use in diesel engines. It is made from vegetable oils, recycled fryer oils, tallow and other biological products. The viscosity of these oils is reduced by using a process called tranestrification. Thereby glycerin, a thick component of vegetable oil, is removed. Biodiesel is a light to dark yellow liquid. It has a high boiling point and low vapor pressure. Typical methyl ester biodiesel has a flash point of 150 °C, making it rather non-flammable. Biodiesel has a lower density than that of water. Biodiesel is, non-toxic, and essentially free of sulfur and aromatics.
Biodiesel is either used as blend of fossil diesel fuel or unblended as pure biodiesel. B5 is a blend of petroleum-based diesel (95%) and biodiesel (5%) B30 is a blend of petroleum-based diesel (70%) and biodiesel (30%) B100 is non-blended biodiesel.
Biodiesel can be distributed using today's infrastructure, and its use and production is increasing rapidly. Fuel stations are beginning to make biodiesel available to consumers, and a growing number of transport fleets use it as an additive in their fuel. Biodiesel is generally more expensive in production than petroleum diesel, but in some countries tax excempions make it cheaper than fossil diesel. The difference in production costs may diminish due to economies of scale, the rising cost of petroleum and government tax subsidies.
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What is bioethanol? |
Ethanol can be produced either by petrochemical feedstock or by fermentation. Bioethanol is an alcohol, and most is made using a process similar to brewing beer where starch crops are converted into sugars, the sugars are fermented into ethanol, and then the ethanol is distilled into its final form. Bioethanol can be produced from any biological feedstock that contains appreciable amounts of sugar or materials that can be converted into sugar such as starch or cellulose.
Bioethanol is readily obtained from the sugar or starch in crops. Maize and sugarcane are two examples for typical feedstocks. Further, bioethanol can be produced from a variety of other crops, such | | | |
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