Generating Electricity

Generating Electricity

1. Fossil Fuels

   • Chemical energy is burned, heat turns water (gas doesn't) to steam, vapour turns turbine, kinetic energy turns magnet inside coils in generator.
   • Shortest Start up time: Gas, Oil, Coal, Nuclear: Longest Start up time
   • Ad: Large scale production, Established technology, cheap, continuous, controlled amount can be produced.
   • Dis: CO2, global warming, weather conditions, SO2, acid rain, environment, dust and ash if not cleaned, nonrenewable.
   • Nuclear
     • A neutron collides with a uranium atom, and the U atom splits up.
       • The heat produced turns water to steam which turns a generator producing electricity
       • Boron rods (where the neutron is from) are lifted up and down in the reactor to control how much fission occurs.
     • Ad: Large scale production, established tech, cheap, 10000 times more energy is released that other fossil fuels, No emission of CO2 or SO2.
     • Dis: risk of nuclear accident, waste is dangerous and takes ages to become safe, difficult to dispose of, taking it out of use it expensive,

2. Wind Power

   • Wind drives a generator that produces electricity
   • Placed on tall towers on hilly sites
   • Ad: wind is free, no pollution or waste, does not take up much ground space, can be used in remote locations (at sea), cheaper to take down.
   • Dis: more wind off shore but you have to get power back to land, a lot more are needed to replace a powerstation, wind unreliable, visual
     • Polltion, large areas of land required, some noise pollution, interfere with tv and radar signals, can kill wildlife, only some suitable places.

3. Definitions

   • Renewable energy: energy from sources that never run out.
   • Carbon-neutral: fuels that neither contribute to nor reduce the amount of carbon in the atmosphere

4. Tidal Power

   • Turbines generate electricity by being moved by tide twice.
   • Ad: tide is free, no pollution, no fuel, produces an ok amount.
   • Dis: Only happens twice a day, expensive for electricity, few potential sites, damning can effect enviro and local area, expensive to install
     • may harm wildlife, restricts river access.

5. Wave power

   • 2 types: Pelamis sit on top of water and generate electricity by rise and fall. no. 2 traps water and the pressure of the wave coming in spins turbine
     • Ad: wave is free, no pollution, large amounts of electricity (20 MW per Km)
     • Dis: expensive electricity, only effective when there are strong waves, noisy, harm wildlife, hazard to boats, non constant supply, wires to mainland

6. Hydro-Electric

   • High region to lower, water flows from top of dam and turns turbines. In times of low demand water is pumped to top then released in high demand.
   • 1/6 of world electricity, 90% renewable.
   • Ad: operating costs are low, no pollution, reliable tech, large amounts of power, generated constantly, water is recycled, low electricity cost
   • Dis: Dams - expensive to build, large scale flooding, may harm marine/wildlife, limited potential sites, in remotes areas which costs to travel

7. Solar Power

   • Photo-voltaic cells are used to capture and transfer energy.
     • Thermal: water pipes under black matt surface (heat water)
     • Electric: solar cells flow through 2 types of silicon and knock electrons out, 1st layer - negative effect, 2nd positive charge.
       • Then flow in opposite directions across Pn junction to create current.
   • Useful in remote areas, when small amounts of power is needed
   • Ad: Sun is free, low running costs, no pollution, electricity s generated where it will be used, cost with decrease with improved tech
   • Dis: doesn't work at night, photovoltaic cells are expensive, power output is low, large areas are required for reasonable power output, expensive.

8. Carbon Capture

   • Capturing waste carbon dioxide and storing it e.g. underground.
   • Ad: reduces CO2 from the air, old oil/gas fields can be used as storage space.
   • Dis: expensive, cannot be used at sea.

9. Geothermal

   • Natural heat within the earth, sometimes heat can rise to the surface in liquids or gases near plate tectonic boundaries.
     • We drill 6km into the earth and dump water into the hole. The earth heats the water which turns to steam and turns a turbine.
   • Ad: operating systems are low, no pollution
   • Dis: no many sites, drilling through some rock is difficult, dangerous gases and minerals can be omitted.

10. The National Grid

    • Electricity travels from powerstation to cables
      • Step up transformer; turns voltage up and current down to inhibit heat loss along lines
        • step down transformer turns voltage down so house hold appliances can use power and current up.
          • Substation turns voltage down (adapter) to safe levels
        • Heat loss every sec or the Power = I times I R(I = current, R = resistance of wires)
    • Over Ground: spoil landscape, may effect health, high above ground.
    • Under ground: hard to repair, expensive, are not far underground so could affect people more.