Ethanol fuel is an alternative to gasoline. It can be combined with gasoline in any concentration up to pure ethanol (E100). Anhydrous ethanol, that is, ethanol with at most 1% water, can be blended with gasoline in varying quantities to reduce consumption of petroleum fuels and in attempts to reduce air pollution. Worldwide automotive ethanol capabilities vary widely and most spark-ignited gasoline style engines will operate well with mixtures of 10% ethanol (E10).
In Brazil, ethanol-powered and flexible-fuel vehicles are manufactured to be capable of operation by burning hydrated ethanol, an azeotrope of ethanol (around 93% v/v) and water (7%). Hydrated ethanol may also be mixed with gasoline in flexible fuel vehicles but a minimum amount of ethanol (granted by legally regulated gasoline type C) is required to avoid problems with the mixture. A few flexible-fuel systems, like Hi-Flex, used by Renault Clio and Fiat Siena, can also run with pure gasoline.
Ethanol is increasingly used as an oxygenate additive for standard gasoline, as a replacement for methyl t-butyl ether (MTBE), the latter chemical being difficult to retrieve from groundwater and soil contamination. At a 10% mixture, ethanol reduces the likelihood of engine knock, by raising the octane rating. The use of 10% ethanol gasoline is mandated in some cities where the possibility of harmful levels of auto emissions are possible, especially during the winter months.[1] Ethanol can be used to power fuel cells, and also as a feed chemical in the transesterification process for biodiesel.
Ethanol can be mass-produced by fermentation of sugar or by hydration of ethylene from petroleum and other sources. Current interest in ethanol lies in production derived from crops (bio-ethanol), and there's discussion about whether it is a sustainable energy resource that may offer environmental and long-term economic advantages over fossil fuels, like gasoline or diesel. It is readily obtained from the starch or sugar in a wide variety of crops. Ethanol fuel production depends on availability of land area, soil, water, and sunlight.
In 2004, around 42 billion liters of ethanol were produced in the world,[2] most of it being for use in cars. Brazil produced around 16.4 billion liters and used 2.7 million hectares of land area for this production (4.5% of the Brazilian land area used for crop production in 2005. [3] Of this, around 12.4 billion liters were produced as fuel for ethanol-powered vehicles in the domestic market.
