Educating curious minds on the magic of energy
All About Electricity
Electricity is a type of energy involving the movement of charged particles. It has always been around but even today we struggle to understand exactly what electricity is.
For years electricity has been a source of wonder and amazement to scientists. Whilst science has known about its existence, scientists have found it hard to explain exactly what electricity is. Electricity has no weight but can lift and move thousands of tonnes, it has no shape but is everywhere.
The basic unit of electricity is the watt, named after the Scottish inventor James Watt (1736-1819), who perfected the steam engine and the rotary engine. Watt also coined the term “horsepower” as a measure of how much work an engine was performing. The watt, on the other hand, is the unit of power in the metric system. A watt is the amount of power that is delivered when a current of one ampere flows through an electric circuit and a voltage of one volt exists across it. It is quite a small unit of power. Typically, household lighting draws between 20 and 100 watts. Household appliances like hair dryers, toasters, heaters and kettles draw 500 to 1500 watts of power. A household electrical bill is measured in kilowatt hours. A kilowatt is 1,000 watts. If you operated a 1,000 watt heater for an hour you would have used a kilowatt hour of electricity. Power station output is measured in millions of watts or megawatts. A 200 megawatt unit generates enough electricity to supply a city the size of Bendigo at peak times or a city the size of Geelong at quieter times.
The Pelican Point Power Station uses an ingenious method of electricity generation. It is a Combined Cycle Gas Turbine (CCGT) Power Station. In essence it recycles its fuel to maximise its electricity output, thereby increasing the energy efficiency of the station (efficiency refers to how well the power station transforms energy from gas to electricity). The process of generating electricity at Pelican Point power station works like this:
- Natural gas arrives at the power station via a pipeline.
- The gas is burnt in a mixture of compressed air.
- The air is drawn through filters and then compressed.
- 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 more than 53 per cent.
- 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 in turn cooled in the plant’s cooling towers before being returned to the sea at no more than two degrees above its original temperature.
Each of the three generators at Pelican Point produces electricity at 15,700 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.
TAKE THE FOLLOWING QUIZ TO TEST YOUR KNOWLEDGE!
The Ancient Greeks
The simultaneous generation of heat and electricity, typically where the need for both arises for industrial or commercial purposes.
Pelican Point Education Centre
All tours must be booked through Mobile Science Education.
- Maximum of 30 students per tour.
- Tours are run on Tuesday, Wednesday and Thursday (contact Mobile Science Education for times). Other times can be arranged to suit.
- Each tour takes approximately 1.5 hours.
- Tours are run to suit the age of the students or the purpose of the group
- Local community groups are also welcome to visit the centre
For more information please contact Mobile Science Education directly via the details below: