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First generation BIOFUELS
...
What is biofuel?
Biofuels are any liquid, solid or gaseous fuels
produced from organic matter. The
extensive range of organic materials used
for biofuel production includes starch and
sugary plants such as corn, wheat or sugar
cane; oily plants such as rape seed, soya
beans or jatropha; vegetable oils and
animal fats; wood and straw; algae and
organic waste and others.
First Generation Biofuels
• The two most common 1st generation biofuels are bioethanol from starch or sugar crops and biodiesel from oil-rich plants. As these fuels are primarily derived from crops which may also be used as food for animals and humans.
Vegetable Oil-Edible vegetable oil is generally not used as fuel, but lower quality oil can be used for this purpose. Used vegetable oil is increasingly being processed into biodiesel, or (more rarely) cleaned of water and particulates and used as a fuel.
Biodiesel- Biodiesel is the most common biofuel in Europe. It is produced from oils or fats using transesterification and is a liquid similar in composition to fossil/mineral diesel. Its chemical name is fatty acid methyl (or ethyl) ester (FAME).
• Bioalcohol-:Biologically produced alcohols, most commonly ethanol, and
less commonly propanol and butanol, are produced by the action of microorganisms and enzymes through the fermentation of sugars or starches (easiest), or cellulose (which is more difficult).
• Bioethers-:Bio ethers (also referred to as fuel ethers or fuel oxygenates) are
cost-effective compounds that act as octane enhancers. They also enhance engine performance, whilst significantly reducing engine wear and toxic exhaust emissions. Greatly reducing the amount of ground-level ozone, they contribute to the quality of the air we breathe.
• Syngas-: Syngas, a mixture of carbon monoxide and hydrogen, is produced by partial combustion of biomass, that is, combustion with an amount of oxygen that is not sufficient to convert the biomass completely to carbon dioxide and water. Before partial combustion the biomass is dried, and sometimes pyrolysed.
• The resulting gas mixture, syngas, is itself a fuel. Using the syngas is more efficient than direct combustion of the original biofuel; more of the energy contained in the fuel is extracted
• Solid Biofuels-:Examples include wood, sawdust, grass cuttings, domestic refuse, charcoal, agricultural waste, non-food energy crops (see picture), and dried manure.
• When raw biomass is already in a suitable form (such as firewood), it can burn directly in a stove or furnace to provide heat or raise steam.
• Biogas-:Biogas is produced by the process
of anaerobic digestion of organic material by anaerobes. It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields.
Poplar grown for fuel in the UK.
Green diesel
• Green diesel, also known as renewable diesel, is a form of diesel fuel which is derived from renewable feedstock rather than the fossil feedstock used in most diesel fuels. Green diesel feedstock can be sourced from a variety of oils including canola, algae, jatropha and salicornia in addition to tallow. Green diesel uses traditional fractional distillation to process the oils, not to be confused with biodiesel which is chemically quite different and processed using transesterification.
• “Green Diesel” as commonly known in Ireland should not be confused with dyed green diesel sold at a lower tax rate for agriculture purposes, using the dye allows custom officers to determine if a person is using the cheaper diesel in higher taxed applications such as commercial haulage or cars.
Ethanol yield from selected sugary materials (sinha and kishore,1991)
Raw material Possible production(t/ha)
Carbohydrate content(%)
Ethanol yields (litre/t)
Beet 40-50 16 90-100
Sugarcane 50-100 13 60-80
Maize 4-8 60 360-400
Wheat 2-5 62 370-420
barley 2-4 52 310-350
The three main methods for the development of biofuels:
1. burning of dry organic wastes
2. energy forestry
3. the fermentation of wet wastes
Plant oil
Pressing and extraction
Rapseed, palm, soya, sunflower plant
esterification
separation
biodiesel
hydrogenation
Diesel fuel
glycerol
methanol
Directly from plant
Commercial production of ethanol involves
three steps-:Wheat straw(500gm)
Cellulosic pulp(400gm)
xylose(40gm)
Glucose(105gm)
ethanol
(10gm) ethanol
(42gm)
1.Preparation of substrate
2. Fermentation3. Distillation
Why Use Biofuels over Fossil Fuels?
Biofuels - Are They The Future?
What are the benefits of biofuels?
Drawbacks of first generation biofuel• contribute to higher food prices due to competition
with food crops;
• are an expensive option for energy security taking into account total production costs excluding government grants and subsidies;
• provide only limited GHG reduction benefits sugarcane ethanol, and at relatively high costs in terms of $/tonne of carbon dioxide ($/t CO2) avoided;
• do not meet their claimed environmental benefits because the biomass feedstock may not always be produced sustainably;
• are accelerating deforestation (with other potentially indirect land use effects also to be accounted for);
• potentially have a negative impact on biodiversity; and
• compete for scarce water resources in some regions.