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Coal Electricity
Generation
When it nears our homes, businesses and schools,
In the case of Yallourn the material at the surface
the electricity is converted to safer level of 240
of the mine, known as overburden, is removed by
volts (at the distribution substation), which is used
the use of Bucket Wheel Excavators or Dredgers
EnergyAustralia Coal
Electricity Generation
Coal is a fossil fuel which is a natural substance,
to power all our electrical appliances including
to reveal the coal. The coal is then dug up, using
Every hour at the EnergyAustralia Yallourn power
and is one of the world’s most important sources
televisions, game consoles, fridges, toasters
bucket wheel excavators or large dozers and
station, 2,200 tonnes of brown coal are used to
of energy that is used to generate around 37%
and washing machines.
loaded on to conveyer belts which transport the
boil water into superheated steam to drive the
of electricity worldwide.
How is coal formed?
coal to the coal bunkers which provide around
four turbine generators. These turbines have a
20 hours of coal storage for the power station.
combined capacity of 1,480 megawatts of electricity
Coal is a type of rock formed millions of years
As areas of the mine are depleted of coal, the
and generate approximately 10,500 gigawatt hours
ago from plant and mineral materials in swampy
land is rehabilitated so it can fulfil a new purpose.
areas. Over time, sediments covered these materials,
Rehabilitation typically includes reducing the slope
forming heavy rock layers. This forced the plant
of the steeper mine walls and capping over coal
material to decompose into a spongy material called
surfaces. Once this is done, indigenous vegetation
peat. As the water and gasses were squeezed out
can be introduced into the area which will generally
by the heavy rock layers, above the peat was heated
include plants, trees and grasses. In some cases,
*
How is coal converted
to electricity?
Coal is burnt in power stations to generate electricity.
Generally, brown coal is first ground into a powder
which allows it to burn more quickly. The powdered
coal is burnt at a high temperature of around 1100
degrees Celsius. The heat converts into steam.
per annum. This is enough to supply electricity
to around 2 million homes.
Useful links
at great temperatures in the earth and coal began
rehabilitation can also involve man made lakes.
Powerworks
The high-pressure steam is passed into the turbine,
to form, first as brown coal (lignite) and then harder
The revegetation of depleted mines can provide
http://www.powerworks.com.au
which is connected to a generator which is in turn
black coals. The coal formed in layers called seams.
a potential habitat for wildlife in the region.
Brown coal is a relatively young coal at around
connected to the electricity grid.
World Coal Association
When the steam is passed into the turbine it
30 million years old compared to black coal
Coal to the Power Station
http://www.coal.org
causes the turbine shaft to rotate at high speeds
which is 10 to 20 times older. The brown coal
From the mine, the coal is carried through crushers
CSIRO
(the speed is usually fixed at 3000 rotations per
seam at Yallourn is around 100m in depth and
into the short-term boiler bunkers of each of the
http://www.csiro.au
minute). This energy is converted into electricity by
there are other seams lower down. The brown
generating units. The coal is then delivered to the
the generator and passed into the electricity grid.
coal is characterised by being relatively high in
pulverised fuel mill to be crushed into a powdered
At our Yallourn power station in the LaTrobe Valley
moisture content (60 to 70%) but very low in
consistency. In conjunction with the crushing, hot
in Victoria, the electricity generated is passed through
ash and sulphur as compared to black coal.
gases drawn from the furnance. The mill, acting
a transformer which converts the voltages (a unit
of measure for electricity) to a level appropriate
How is coal mined?
for the transmission lines. The transmission line
At the EnergyAustralia power station, brown coal
The heat from the coal combustion is transferred
transports the power to the networks where
is mined in the adjacent open cut mine. Open cut
into the boiler surfaces thereby generating steam
EnergyAustralia Pty Ltd
the voltage is lowered at a zone substation to an
simply means that coal is mined at the surface,
to be delivered to the turbine.
appropriate level for industrial and commercial use.
rather than by using underground methods.
*Source: Australia Coal Association
ABN 99 086 014 968
Locked Bag 14060
Melbourne VIC 8001
Energy Information Sheets
as a large fan, then delivers the pulverised fuel
(powdered coal) into the furnace where it ignites.
A Typical Coal Fired Power Station
F
A
J
K
L
E
D
B
C
I
G
H
A Conveyor
D
Boiler
G Ash Systems
J Turbine
B Coal pulveriser
E
Precipitator
C Furnace
F
Stack
H Cooling pond
I Condenser
K Generator
L Substation Transformer
Energy Information Sheets
EnergyAustralia Pty Ltd
ABN 99 086 014 968
Locked Bag 14060
Melbourne VIC 8001