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10.2 Transferring energy
The manufacture of Transferring stored energy
filament light bulbs The chemical energy stored in the form of fossil fuels such as oil, gas
has stopped around and coal is transferred as heat and light through combustion. In a power
the world, including station, this is transferred by means of heating water and generating
textbooks nis edu kz
in Kazakhstan. Why steam. This steam puts generators (devices that generate electricity)
into action. Generators produce electricity which is then transferred
do you think this
to devices across the country. Another part of chemical energy is
has happened?
transferred to the environment by means of heating materials and air in
power stations and powering the work of household devices (a lamp, for
example). This energy cannot be restored: we say ‘energy was transferred
to the surroundings’. Energy is constantly being transferred.
Let us consider another example. A car needs fuel to start moving.
Burning fuel generates a large quantity of heat energy, which powers
the engine. This also increases the temperature of the surroundings.
Other examples include the electric kettle, which transmits heat to the
environment as it heats up, or the friction generated between parts
of a working mechanism. Of course, friction can be reduced using oil
or lubricant, but it is impossible to remove it completely. Sometimes
friction causes excessive heat, and this also leads to energy being
transferred to non-useful energy.
Efficiency of energy transfers
The main issue regarding energy transfers is that of efficiency. This
concept relates to how much energy needs to be transferred for a
Thermal image of a car’s engine, device to do what we want it to do, and how much energy is transferred
while the engine is running
to the surroundings without it doing the work we want it to do. This
energy is dissipated, heating up the surroundings of the device and the
air around it, and it becomes difficult to re-use.
100%
fuel energy
65%
heat energy
(wasted
energy)
1% 2% 7% 25%
acoustic energy
(audio systems driving energy
and signal) light energy work expended on
(car light) overcoming internal
friction forces
The diagram demonstrates all possible energy losses in liquid fuel
engines. Losses occur due to unburned fuel, due to heat through the
cooling system and due to exhaust gases. There are also mechanical
losses due to internal friction. The Sankey diagram represents the
different energy transfers to scale.
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