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The two main types of biofuel are Biogas and Gasohol. The biofuel comes from biomass, which is
living or recently-dead organic material, for example plant matter. The biomass is a store of energy
and this energy can be transferred into fuels.
Biogas contains about 60% methane and 40% carbon dioxide. These numbers are approximate and
they also include traces of hydrogen, nitrogen and hydrogen sulphide gas. Biogas burns easily when
there is around 50% methane, but if the level drops to 10%, this would make the methane explosive.
Biogas is made by anaerobic fermentation of waste material. It is the bacteria's respiration that
Biogas has three main uses:
It is burned to generate electricity
It is burned to heat water and produce steam for central heating systems
It is used as a fuel for cars and other motor vehicles
Biogas is created by fermenting waste organic matter. It is put in a simple fermenter, which is called a
digester. Bacteria decompose this organic matter and create the biogas. The fermentation takes
place without oxygen and this known as being anaerobic. The fermenter is kept at 30-40 degrees as
this is the optimum temperature for the bacteria's respiration. The bacteria produce biogas quickly at
Gasohol is a mixture of ethanol and petrol. Ethanol can be burnt as fuel. Gasohol is used for fuel in cars
and this also known as a biofuel. Ethanol is a renewable resource and it produced by using yeast to
ferment glucose. The gasohol contains 90% petrol and 10% ethanol and this means that less pure
petrol is being used.
Petrol is made from crude oil, which is a non-renewable energy source. By using only 90% petrol,
less of this crude oil is being used up and therefore it is better long term. Some countries, such as
Brazil use gasohol as a major part of their energy sources. This is a viable thing in this area as they
have lots of land in which they can grow the sugar cane from. In Brazil, this is also important to do
because they do not have much oil and this is much cheaper than importing form somewhere else.
Some countries will not be able to benefit from gasohol because they do not have the land space to
grow the sugar cane, which needed for the ethanol to be released.
Advantages of bio fuels Disadvantages of bio fuels
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The fuels can be produced in a It does not contain as much energy as it
sustainable way. They can be replaced is diluted
with new crops when the others have Large areas of land must be lost to use
been used up for making the bio fuels
They are a renewable resource Habitat loss
The plants will photosynthesis and will Loss of space for crop production
remove carbon dioxide from the