BIOFUELS:
AN EMERGING SOURCE OF ENERGY
Biofuels are fuels derived from living matter such as corn and algae.
WHAT ARE BIOFUELS?
What are Biofuels?
Biofuels are fuels such as ethanol and biodiesel, mainly used for transportation. They are an alternative to traditional fossil fuels (coal, oil, natural gas). Biofuels are created from plants such as corn, soybean, algae and grasses. They are also made from starch crops such as potatoes, and sugar crops such as sugarcane and animal fats. Through a process of fermentation, sugar and starch crops are made into ethanol. Vegetable oils and animal fats are made into biodiesel. (H.1)
(V.1)
What are the different types of Biofuels?
Some biofuels that have been used for a long time are wood or grass to produce heat that can be used to produce electricity. There are also liquid biofuels which are mainly used for transportation purposes. Ethanol is a liquid biofuel in greatest production currently. (H.2)
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Two of its leading producers are Brazil and the United States. In the United States, ethanol biofuel is blended with gasoline, containing 10-15% ethanol. In Brazil, ethanol is made from sugarcane and is blended with gasoline containing 85% ethanol or used as 100% ethanol fuel. (H.2)
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Another common liquid biofuel is biodiesel. It is used in diesel engines and can be blended with petroleum diesel for various content levels. Methane gas and biogas are also forms of biofuels made from the decomposition of biomass. (H.2)
How are Biofuels classified and made?
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Biofuels are classified into four generations
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classified by their limitations, technological progress, and their sources of biomass.
First Generation Biofuels
First generation biofuels are made from food sources and are sometimes known as conventional biofuels. Fermentation,distiallation, and dehydration are the three steps in making ethanol. In fermentation, microbes in yeast break down sugar and convert it into ethanol and carbon dioxide and during distillation, the water is removed from the ethanol. Extra water is then removed through a process known as dehydration in order for ethanol to burn with gasoline. (H.3) Biodiesel is produced through transesterification. In this process, oil reacts with an alcohol (methanol) in the presence of a catalyst and in distillation, the biodiesel separated from the by-product, glycerol. (H.4)
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Second Generation Biofuels
Wood, organic waste, and food waste are used to make second generation biofuels. Poplar trees need to go through a pretreatment procedure to break down lignin, (a glue that holds plants together) to make fuel. In this procedure, biochemical reactions take place to unwind the sugars embedded in fibers of the plant. After this, the process of turning it into a biofuel is similar to ethanol production. (H.4)
(V.2)
Third Generation Biofuels
Third generation biofuels depend upon algae as the energy source. Algae are specially engineered crops, harvested to extract oil. The oil then turns into biodiesel through transesterification and distillation or can be purified into other fuels as replacement. Third generation biofuels can be made at low-cost, provide high energy and are renewable sources. One advantage that algae provides is that it can be grown in harsh, unsuitable areas and can be grown in salt lakes or oceans. Research is still being conducted to make algae based fuels like other petroleum-based fuels. (H.4)
(V.3)
Fourth Generation Biofuels
Fourth generation biofuels are made from inexpensive and available raw materials. They are based on synthetic biology of algae and cyanobacteria, redesigning them to make biofuels. Fourth generation biofuels are produced through three ways: designer photosynthetic microorganism produce solar fuels, combining photovoltaics and electrobiofuels, and designing synthetic organelles to produce desired biofuels. Because of their photosynthetic chassis, Cyanobacteria are genetically engineered to produce biofuels such as ethanol and isobutanol. MES is an emerging field where energy from solar cells is turned into electrofuels, (storable energy sources). Engineered MES organisms produce fuel butanol and provide an effecient way to store solar energy in the form of liquid fuel. (H.5)
