Energy Efficiency

ENERGY TRANSFORMATIONS

Energy is always conserved (changed from one form to another); this is known as transformation



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Energy can be in use (active or kinetic) like light or heat energy

Energy can also be stored which is known as potential energy because it has the potential to be used


Here are some examples of kinetic and potential energies


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Fuels contain chemical potential energy which is released when we burn them and break their bonds




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ENERGY EFFICIENCY

When we use fuels the chemical potential energy is transformed to heat, light and sound.

Heat is the desired output energy and the light and sound are considered waste energy


Most normal light bulbs are around 10% efficient, this means that of all the energy that goes in only around 10% of it is turned into the desired energy output; light.

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More information on energy efficiency can be found here

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/energy/heatrev6.shtml


ENERGY EFFICIENCY OF FUELS

When we burn fuels we are transforming the chemical potential energy into heat, sound and light


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The amount of energy that is released depends on 2 factors

1) The size of the molecule (fuel) that we are burning

2) The type of combustion (see combustion topic)



The more chemical bonds that we break the more energy is released so the bigger the molecule the more energy released

Ethanol
How many bonds does ethanol have? Count all the lines between atoms

How many bonds does butane have? Count all the lines between atoms
How many bonds does butane have? Count all the lines between atoms


When we count the bonds we see that ethanol has 5 less bonds than butane so we would expect butane to release more energy when combusted



Complete combustion is more energy efficient than incomplete combustion; it releases more energy
Notice the smoky flame from incomplete combustion. If we were to measure the heat given off we would expect the complete combustion to give off more heat energy
Notice the smoky flame from incomplete combustion. If we were to measure the heat given off we would expect the complete combustion to give off more heat energy

For more information on combustion go to https://wsc11sci.wikispaces.com/Combustion


For more information on ethanol vs fossil fuels go to https://wsc11sci.wikispaces.com/Producing+Ethanol