¿cual es el mejor, biodiesel o bioetanol?
They are types of fuels solids,liquids and gases.Liquid is good because of high energy density and is clean.
What is ethanol?
Most transportation fuels are liquids, because vehicles usually require high energy density.
Biodiesel and bioethanol
Biodiesel is an alternative fuel to diesel. It cannot be used on its own in traditional internal combustion engines but can be blended with traditional petroleum fuel.
Bioethanol can be used on its own or in a blend with petrol (gasoline).
Overall, biofuels make up 5% of the petroleum blend in the UK.
Biodiesel is produced from oil-seed crops, such as oilseed rape, sunflower oil, palm oil and soybean oil.
Oilseed rape is the main oil crop in the UK and yields approximately 1,300 litres of biodiesel per hectare planted.
Biodiesel is synthesised from the oil seeds by mixing them with two industrially sourced chemicals, methanol and either sodium hydroxide or potassium hydroxide.
This reaction causes the formation of fatty acids and glycerol, with the fatty acids reacting further to produce biodiesel.
Most biodiesel production is currently in Europe, but it is not limited to the developed world. Tanzania, for example, has started producing biodiesel from the nuts of the croton tree (Croton megalocarpus), a plant native to South-East Asia.
Several countries, notably India, are using biodiesel obtained from Jatropha curcas oil as a fuel. Indeed the trains that run between Mumbai and Delhi now use diesel that contains 15% biodiesel obtained from Jatropha. This plant has several advantages as a source of biofuel - it can tolerate drought conditions, and it grows on poor land that is unsuitable for agriculture and so does not compete with food production.
Bioethanol is currently produced by the fermentation of sugar by microbes. Microbes use the sugar as a food source and convert it to ethanol.
In order for the ethanol to be used as fuel it needs to be separated from the other components of the fermentation reaction, usually by the process of distillation.
Typically the mixture is heated and, as the ethanol boils at a lower temperature than the other components, it is transformed into a gas first and this gas can be collected and then condensed (transformed back to liquid bioethanol).
The purified bioethanol can be mixed with petrol for use in car engines.
Currently, countries using bioethanol include Brazil, France, the USA, the UK, Argentina and South Africa.
In Brazil use has been particularly widespread, however, this has been at the expense of large tracts of natural vegetation including rainforests. It is estimated that one-third of cars in Brazil run entirely on bioethanol and the remaining two-thirds use a mixture of bioethanol and petrol (gasoline).