Thermal coal (also known as steaming coal) is used for electricity production.
In Australia, black coal is responsible for 54.9% of electricity production and when combined with brown coal (21.8%) provides for more than 75% of the nation’s electricity. In some states, such as NSW, black coal share of energy production is around 90%.
Coal is one of the main reasons that Australia enjoys some of the cheapest electricity prices among OECD countries. This helps to underpin energy intensive industries including manufacturing, a sector that employs almost one million Australians.
Globally, coal provides for 29.6% of primary energy needs and generates 42% of the world’s electricity. The low cost of coal relative to other fuel sources means it is a critical resource for developing economies, with electrification being directly linked to the alleviation of poverty.
Coal Use in Electricity Generation
The earliest conventional method for generating electricity was by burning lump coal on a grate in boilers to raise steam.
In modern, highly-efficient, versions of this system, the coal is first milled to a fine powder in a pulveriser. This increases the surface area of the coal and hence the rate of combustion. The powdered coal is blown into the combustion chamber of a boiler where it is burnt at around 1400°C. The hot gases and radiant heat energy produced convert water in tubes lining the boiler into steam.
The high-pressure steam is passed into a turbine containing thousands of propeller-like blades. The expanding steam hits these blades causing the turbine shaft to rotate at high speed.
Mounted at the end of the turbine shaft is the generator, consisting of carefully wound wire coils. Electricity is generated when these are rapidly rotated in a strong magnetic field.
After passing through the turbine chamber, the steam is condensed and returned to the boiler to be heated once again.