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Education Resources

How does gas fired power work

What is natural gas and why is it important?

Natural gas is a colourless, odorless, flammable gas that usually contains about 90% methane.

It can be found in deep underground rock formations, often alongside oil or coal.

It’s one of the main energy sources in the world. 

How does a gas-fired power station work? 

Gas-fired power stations burn natural gas to produce electricity.

There are two main ways they do this – open cycle and combined cycle.

Open Cycle Gas Turbine

Open-cycle production is the most common method. Natural gas is burned to create a pressurised gas, which powers a turbine that is connected to a generator. The turbine turns the magnets in the generator to create electricity.

Combined Cycle

The Combined-Cycle Gas & Steam Turbine (CCGT) plant generates energy using two different types of turbines in combination: a gas turbine and a steam turbine. In essence, it recycles its fuel to maximise its electricity output. 

 

Pelican Point Power Station Energy Generation Process

  • Natural gas arrives at the power station via a pipeline.
  • Air is drawn through filters and then compressed 
  • The natural gas is mixed with the compressed air, and this mixture is then burnt in a combustor.
  • This process produces high pressure, high temperature combustion gases that drive a turbine connected to a generator. 
  • The generator spins an electromagnet at very high speed (about 50 times a second), inside copper wire conductors. 
  • This generates electricity. 
  • The exhaust gases from the turbines are then directed to the Heat Recovery Steam Generator where it is used to boil water in a series of pipes, producing superheated steam. 
  • Any remaining exhaust gas is released through a large chimney. 
  • The superheated steam is delivered to a steam turbine, which in turn drives another generator to produce electricity. 
  • The steam powered turbine and generator increases the overall efficiency of the gas/steam turbine (or combined cycle) operation of the power station to around 53%.
  • The steam used to rotate the steam turbine is directed to a condenser, where it is cooled back into liquid water for reuse in the boilers.
  • 10,000 litres of seawater per second is pumped through the condenser for this purpose. 
  • The seawater is returned to the sea. 
  • Each of the three generators at Pelican Point produces electricity at 15,750 volts. 
  • The voltage of the electricity is increased to 275,000 volts at the step-up transformers before being delivered to the switchyard and the National Electricity Grid. 
  • It is then transformed into lower voltage to be used in our homes, schools, shops and factories.
  • This whole process is monitored and controlled at the station’s control room.