P2 - Sustainable Energy

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  • P2 - Sustainable Energy
    • Energy Stores & Transfers
      • Energy Stores: Thermal, Kinetic, Gravitational Potential, Elastic, Chemical, Nuclear, Electromagnetic and Electrostatic.
      • Energy can be transferred by heating (hotter to colder region) or by working.
        • Mechanical Work: object moving due to force).
        • Electrical Work: against resistance (charges round a circuit over long dsitances)
          • E.g. Motors or to lift weights
      • Describe the energy transfers that occur in a battery-operated motor.
        • Energy is transferred electrically from the chemical energy store of the battery to the kinetic energy store of the motor. (Thermal wasted).
    • Conservation of Energy & Power
      • Energy is always conserved. It can be transferred usefully, stored or dissipated but can NEVER be created or destroyed.
      • Dissipated energy is sometimes called 'wasted energy'.
      • A closed energy system is when the net change is always zero. A spoon in soup in a thermal energy insulator is closed.
      • A mobile phone charging is an open system (thermal energy wasted)
      • ENERGY = POWER X TIME
      • Power is the rate of energy transfer.
      • Energy is measured in joules but can be kilowatt/hours
    • Efficiency & Sankey Diagrams
      • The less energy of a device wasted - the more efficient it is. Streamlining & Lubricating makes a motor more efficiant.
      • EFFICIENCY = USEFUL ENERGY TRANSFERRED / TOTAL ENERGY TRANSFERRED.
      • Reducing Energy Losses In Buildings
        • Thermal Insulation e.g. thick curtains, double glazed windows and draught excluders.
        • Thickness & Thermal Conductivity of Walls.
        • Thicker = lower rate of energy transfer, increasing time taken for a building to cool down.
      • Sankey Diagrams show efficiency by showing useful and non-useful energy transferred.
    • Energy Resources
      • Non-Renewable Energy Source - One that will run out in the foreseeable future. E.g. Fossil Fuels (Oil, Coal & Methane) and Nuclear Fuels.
      • Renewable Energy Source - One that will not run out in the foreseeable future. E.g. Sun, Tides, Biofuels, Wind & HEP
      • D-AD of Fossil Fuels is the impact on the eviroment. Greenhouse effect / Global Warming. Acid Rain
      • Nuclear Waste is dangerous and difficult to expose of.
      • Set-up costs are high for Steam-Turbine Power Stations, but running costs re low.
      • Explain how a power station uses fossil fuels to generate electricity. (4)
      • In most power stations generators produce a voltage across a wire by spinning a magnet near the wire
    • Renewable Energy Sources
      • Wind Power
      • Solar Cells
      • Ask a D-AD & AD for each. If I don't know one I'll look it up.
      • Biofuels -(releases CO2 but plants remove CO2)
      • Hydroelectricity (HEP)
      • Tidal Barrages
    • Trends in Energy Use
      • Good resources need to be easily available, low cost, reliable, little environmental impact and job creators.
      • Does the benefit outweigh the risk or drawback?
      • Demand is increasing globally.
      • UK is slowly increasing the use of renewable.
    • The National Grid
      • Once electricity has been produced using energy resources, it has to be transported to consumers.
      • Transformers are used to increase and decrease the generated electricity from a high p.d to a low p.d and vice versa - reducing energy losses.
      • Mains supply is 230V, 50Hz and a.c.
        • Batteries are d.c. (one direction)
      • LIVE WIRE
        • Brown / carries V, alternates + & - / 230V
        • The human body = earthed conductor at 0V. If you touched the live wire you'd get a large voltage across your body and the current would flow through you, resulting in a large electric shock (injure/death).
          • Even if switched off, still danger as the p.d. is still there in this socket.
            • Your body then provides a link between supply and earth if contact was made.
      • EARTH WIRE
        • Green & Yellow / safety / 0V
      • NEUTRAL WIRE
        • Blue / completes circuit / 0V

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