Power generation/distribution

Generation

Coal

  • Most common method of generating electricity in Australia
  • Uses water and coal as fuel
  • Process is:
    1. Coal is fed into a boiler
    2. Boiler ignites the coal and steam is generated
    3. The high pressurised steam drives a turbine
    4. Turbine is connected to a generator
    5. As turbine rotates due to steam, electricity is generated
  • Readily available in Australia
  • Produces large volumes of greenhouse gases ($CO_2$)
  • Click here for a demonstration

Hydroelectricity

  • One of the alternative energy sources
  • Uses gravitational potential energy of water as fuel
  • Process is:
    1. Large amounts of water are stored within a dam high above the generating station
    2. The water flows down and through the generating station
    3. This movement turns the turbines, generating electricity
    4. The water is then used for irrigation properties
  • This has no atmospheric pollution and has very little waste
  • Yet, this is only available in mountainous regions and requires a lot of impact on the environment due to the large amounts of area needed for dams and channels etc.

Wind power

  • One of the alternative energy sources
  • Uses wind as fuel
  • Process is:
    1. Wind drives large turbines which look like windmills
    2. Turbine is driven and electricity is generated
  • No waste or atmospheric pollution
  • Yet unreliable and also a lot of flat plane is required

Nuclear energy

  • A very controversial method of power generation
  • Process is:
    1. A uranium atom is split, causing immense energy and heat
    2. This heats up water and turns it into steam
    3. The steam then moves past turbines
    4. Electricity is generated
  • No atmospheric pollution is generated and a very small amount of fuel is needed to produce large amounts of electricity.
  • Yet the waste it produces are highly contaminant due to their radioactivity and the generating plants require extreme levels of care.

Solar energy

  • Relatively recent technology within Australia
  • Uses Photovoltaic (PV) cells which converts sunlight into electricity
  • Process is not covered in detail for this course, but basically:
    1. Photovoltaic cells' structure creates an inner electric field
    2. As Photons from sunlight hit the electric field, electrons become "loose"
    3. The loose electrons then move and flow through a circuit
    4. Thus, electricity is generated
  • Since the works is all done by the PV cells, there is very little maintenance required
  • Also there is no waste or pollution created by these cells.
  • Yet, with current technology the efficiency of these cells are quite low (15%)
  • Also high amounts of energy are required to make these PV cells.

Distribution

The Electrical Grid System

  • Other known as 'the grid,' this is the system of electrical power lines that connect power stations to the populace
  • Electrical energy from power plants are distributed via a system of transmission lines to major distribution points and then a distribution network to users.

Generated Voltages

  • Power is generated at different voltages depending on the type of generator
  • Within NSW, most power plants generate at around 20 000 V
  • Yet, to transfer the electric energy through the transmission lines Voltage is transformed to high voltages
  • This is because of the long distance of wire and thus the high resistances involved
  • The high resistance causes some of the electrical energy to be lost through heat
  • As the formula for power loss is: $P_{loss} = I^{2}R$, a low current is desired
  • And as the formula for electrical power is $P = IV$, a high voltage would have a low current

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