Biofuels have been around as long as cars have. But discoveries of huge petroleum deposits kept gasoline and diesel cheap for decades, and biofuels were largely forgotten. However, with the recent rise in oil prices, along with growing concern about global warming caused by carbon dioxide emissions, biofuels have been regaining popularity.
Gasoline and diesel are actually ancient biofuels. But they are known as fossil fuels because they are made from decomposed plants and animals that have been buried in the ground for millions of years. Biofuels are similar, except that they’re made from plants grown today.Read more
There are various ways of making biofuels, but they generally use chemical reactions, fermentation, and heat to break down the starches, sugars, and other molecules in plants. The leftover products are then refined to produce a fuel that cars can use.
Biofuels in India:
Biofuel development in India centres mainly around the cultivation and processing of Jatropha plant seeds which are very rich in oil (40%). The drivers for this are historic, functional, economic, environmental, moral and political. Jatropha oil has been used in India for several decades as biodiesel for the diesel fuel requirements of remote rural and forest communities.It can be used directly after extraction (i.e. without refining) in diesel generators and engines. Jatropha has the potential to provide economic benefits at the local level since under suitable management it has the potential to grow in dry marginal non-agricultural lands, thereby allowing villagers and farmers to leverage non-farm land for income generation.
National Policy on Biofuel 2008 had targeted the blending of biofuel (ethanol and biodiesel) up to 20 per cent by 2017. Also the report had encouraged the biodiesel plantation on community / government / forest wastelands, while plantation on fertile irrigated lands would not be encouraged.
Bioethanol is an alcohol which is made from plants (biomass). Sugar cane, sugarbeet and cereals (wheat and barley) are the most common sources of the fuel. The production first uses enzyme amylases to convert a feedstock crop into fermentable sugars. Yeast is then added to the ‘mash’ to ferment the sugars to alcohol and carbon dioxide, the liquid fraction being distilled to produce ethanol.
Being a liquid at room temperature, bioethanol can be handled in a similar way to conventional petrol. Bioethanol can be used in spark-ignition engines with little or no modification as a low percentage alcohol-petrol blend (‘E10’ is 10% ethanol) or as pure alcohol fuel in modified vehicles. In practice, ethanol as it is routinely added to petrol (as a 5% blend) to improve octane ratings and as an oxygenate additive (to reduce carbon monoxide emissions).
Pure bioethanol is difficult to vaporise at low temperatures, so it is usually blended with a small amount of petrol to improve ignition (E85 is a common high percentage blend). Several manufacturers now offer ‘Flex-Fuel Vehicles’ or ‘FFVs’, which are able to run on any percentage of bioethanol blend up to E85.
Biodiesel is commercially produced by the ‘esterification’ of energy crops such as oil seed rape or from waste vegetable and animal oils (from the food industry). The oils are first filtered to remove water and contaminants and are then mixed with an alcohol (usually methanol) and a catalyst. This breaks up the oil molecules before they are separated and purified.
Low percentage biodiesel blends (B5) can be used in place of mineral diesel without any engine modification in many diesel engines (a ‘B5’ blend is 5% biodiesel mixed with 95% mineral diesel).
While some diesel cars will also run on higher percentage biodiesel blends, their use can degrade rubber products (such as fuel pipes) and clog fuel injectors in certain conditions. To reduce the risk of these problems, users of ester-based biodiesels should ensure the fuel’s compliance with established standards. It is governed by ASTM D 6751 quality parameters
Biodiesel fuel burns up to 75% cleaner than diesel fuel made from fossil fuels. Bio diesel substantially reduces unburned hydrocarbons, carbon monoxide and particulate matter in exhaust fumes. Sulphur dioxide emissions are 100% eliminated (bio diesel contains no sulphur). This alternative fuel is plant-based and adds absolutely no CO2 to the atmosphere.
The Bureau of Indian Standards (BIS) has already evolved a standard (IS-15607) for Bio-diesel (B 100), which is the Indian adaptation of the American Standard ASTM D-6751 and European Standard EN-14214. BIS has also published IS: 2796: 2008 which covers specification for motor gasoline blended with 5% ethanol and motor gasoline blended with 10% ethanol.