Alternative Fuels

Fossil fuels
Crude oil, coal and gas are all fossil fuels.
This is because they come from the fossilised remains of ancient animals and plants.
Issues with Fossil fuels
When fossil fuels are combusted (burned in oxygen). They release CO2
CO2 contributes to global warming.
Issues with Fossil fuels
Fossil fuels also contain impurities.
Sulfur dioxide (SO2) and nitrogen oxides (NOx) cause acid rain.
Issues with Fossil fuels
Some fuel doesn’t combust fully, so particulates of soot are made.
Particulates cause global dimming.
The key issue with fossil fuels!
They are finite!

Finite is the opposite of infinite.

They are running out.

We have to use increasingly advanced methods of extraction.

This is expensive!
Alternative Fuels
A biofuel is a fuel that comes from a biological source.
A biological source is anything that is living, e.g. plants.

Example Biofuel - Biodiesel
Vegetable oil is used for cooking.
It is the oil that comes from plants when they are pressed and squeezed.
Vegetable oil is mostly made of hydrocarbon compounds.
These hydrocarbon compounds are about the same chain length as diesel.
This means we can use vegetable oil to run diesel vehicles (the engine has to be modified slightly).
When we use vegetable oil for this purpose, we call it “biodiesel”.

Example Biofuel - Ethanol
Ethanol is a compound with the formula C2H6O.
It combusts very easily because it already has an oxygen atom in its chemical formula.
Ethanol can be made by a microorganism called yeast.
By feeding sugar to yeast and warming it up, ethanol can be made.

Combustion of Biofuels
Biofuels still release CO2 in combustion reactions.
Biodiesel is made from vegetable oils; as the vegetables grow they take in CO­2 from the atmosphere during photosynthesis.
This means that an equal amount of CO2 is taken in when making biodiesel, as is given off when it is combusted.
If the manufacture of a fuel takes in as much CO2 as is given off when it is combusted, we call it “carbon neutral”.

Carbon Neutral Diagram
Advantages of Biofuels
Biofuels are good for society because they decrease our dependency on imported oil.
They are good for the environment as many of them are carbon neutral and do not contain the same impurities as fossil fuels.
Economically biofuels are good as they can make a lot of money for the farmers growing the biofuel crops.
Also biofuel industry supports skilled jobs, such as chemists!
Disadvantages of biofuels
Biofuel crops take up land that would ordinarily be used for crops, this can push up food prices.
Biofuels are still very expensive as they are not yet common place.
This means government has to subsidise the industry, using money that could be spent on schools, hospitals and other vital public services.
Sometimes forests are cut down for the wood to be used as biofuel. If the forest isn’t replaced, this is not carbon neutral.
Alternative Fuels Questions
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