Numerous technologies are being widened and established for transforming sustainable feedstocks into a variety of biofuels. Environmental and social consequences of biofuels from agricultural crops became the theme of media and drawn several public and private debates and campaigns due to the utilization of first generation technology. Generally, “first generation biofuels” are generated from crops such as cereal, oil and sugar crops to give bioethanol, biodiesel, and biogas employing recognized technology. The use of biofuels has already spread so far that in 2008 1.8% of the world’s transportation fuel derived from such fossil fuel alternatives. And the demand is still rising. Approximately, around 1.38 billion gallons (1 gallon = 3.78 liters) of biofuel are planned to be produced globally by the year 2013. Modern technology is being cultivated to generate biofuels from non food cellulosic matter and other suitable raw materials like algae. These so called “second generation biofuels” are supposed to be more sustainable and do not compete with food production. This article gives an overview about the most widespread types of biofuels.
Bioethanol is commonly produced by the fermentation of starches such as corn, potatoes and grains, sugar from sugar cane and sugar beet, biomass and other agricultural feedstocks. Bioethanol, a liquid alcohol, is often combined with petrol to be used as transportation fuel. In petrol engines, it can as well be an alternative for gasoline and it is the most frequently employed biofuel worldwide. Brazil is known to be the top producer of ethanol from sugar cane followed by the US where bioethanol derives typically from the starch of corn.
A further frequently used biodegradable fuel is biodiesel, which is produced globally in large scales. It is usually made from feedstocks such as waste or vegetable oil (mostly palm or rapeseed oil) or animal fat through a process called transesterification. It´s properties are similar to mineral diesel, and when mixed with such conventional diesel, it can be emloyed in any diesel engine. It has been proven and tested that vehicles fueled with biodiesel work without any problems, and a large number of manufacturers suggest the utilization of 15% biodiesel combined with mineral diesel. In Europe, about 5% biodiesel mixture is commonly provided at gas stations. Top biodiesel producers in Europe are Germany, Italy, Austria, France and globally, the US, Brazil and Argentina. Biodiesel is known to be the best type of fuel that works well with conventional diesel engines.
Biogas, which is in particular methane (and carbon dioxide), is produced by bacteria as they digest cellulosic matter such as corn silage, sewage sludge, liquid manure, cereals and other plant material. Commercially, biogas is fabricated by an industrial biogas generator or from carbon monoxide enriched gas prepared through thermal gasification. It can be employed in motors that are capable to exhaust natural gas, however, currently only small proportion is used for transportation. It is mainly used for the production of electricity and heating. In the production process, a solid byproduct called the digestate is obtained, which can be used as a fertilizer. At present, the USA is the leading country producing biogas, followed by UK, China, and Germany.
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