energy/power

• energy resources

  large stores of energy that can be used to generate electricity and heat homes / business
• how is electricity generated (no matter the energy resource)?

  a turbine is turned, which turns a generator, which generates electricity
• how are fossil fuels used to generate electricity?

  1. they are combusted to heat water
  2. water turns into steam
  3. steam turns turbine
• how are nuclear fuels used to generate energy?

  1. nuclear fuels react with water
  2. steam produced
  3. turbine is turned
• how are bio-fuels used to generate electricity?

  plant matter / ethanol / methane can be produced and used as a fuel in place of fossil fuels.
• how is wind used to generate electricity?

  wind turns turbines directly
• how is hydroelectric energy used to generate electricity?

  1. water is stored at a height
  2. water is released
  3. the rushing water turns turbines directly
• how does geothermal energy generate electricity?

  1. hot rocks underground are used to heat water
  2. produce steam
  3. turbines are turned
• how do solar panels generate electricity?

  1. use thermal radiation to heat water
  2. warm water used for household use
• a renewable energy resource is defined as:

  an energy source that is replenished at a faster rate than the rate at which it is being used
• renewable resources examples

  solar energy, wind, bio-fuel, hydroelectricity, geothermal, tidal
• non renewable energy resources

  fossil fuels and nuclear fuels
• uses of energy resources

  transport, electricity generation and heating
• advantages of fossil fuels?

  reliable

  can produce large amounts of energy at short notice
• disadvantages of fossil fuels?

  produces significant greenhouse gases / pollution
• advantages of nuclear energy

  reliable

  no greenhouse gases / pollution made

  lots of energy can be made from small amount of fuel
• disadvantages of nuclear fuels

  produces dangerous radioactive waste that can take thousands of years to decay
• advantages of bio-fuels

  CO2 produced while burning the fuel is equal to the CO2 absorbed whilst producing it
• disadvantages of biofuels

  can take up a lot of land and resources that are needed for food production
• disadvantages of wind energy

  not reliable - not every location is suitable

  turbines can be noisy and ugly
• advantages of hydroelectric energy

  reliable

  can produce large amounts of energy at short notice

  no greenhouse gases
• disadvantages of hydroelectric energy

  can involve flooding large areas - destroys important wildlife habitats
• what has been the shift in energy resources over the last 20 years?

  government grants have encouraged the development of wind and solar farms.

  coal has gradually been replaced with cleaner natural gas

  nuclear power is becoming an option - nuclear power stations are currently in development
• in the past 30 years, fossil fuel use has dropped from 75% to...?

  38%
• in the past 30 years, renewable energy has increased from 2% to...?

  35%
• why is natural gas now the main provider of energy in UK rather than coal?

  out of the 3 fossil fuels, coal produces the most carbon dioxide while natural gas produces the least
• the process of global warming

  1. the sun emits rays that enter the Earth's atmosphere
  2. the infrared radiation is emitted back from the earth's surface
  3. some infrared radiation is reflected back out into space
  4. some infrared radiation is absorbed by greenhouse gases and becomes trapped within the earth's atmosphere
  5. the earths average temperature rises
• consequences of global warming

  • climate changes
  • glaciers melt --> sea levels rise --> flooding in low lying countries
  • destruction of habitats --> extinction of species
  • migration of species as they move to more habitable areas
  • warmer climate --> spread of disease
• what is the national grid?

  a system of cables and transformers linking power stations to consumers like houses, factories and buildings
• what does the national grid do?

  distribute electricity across the UK
• what do step-up transformers do?

  increase voltage and reduce current through the wires
• what do step-down transformers do?

  decrease the voltage and increase the current through the wires
• why is the national grid system an efficient way to transfer energy?

  due to the use of step-up and step-down transformers
• when electricity is transmitted over large distances, the current in the wires heats them. what does this result in?

  energy is lost through heat
• high potential difference means _____ current (_____ energy loss)

  low and less
• low potential difference means _____ current (_____ energy loss)

  high and more
• uses of transformers

  1. to increase the potential difference of electricity before it is transmitted across the national grid
  2. to decrease the high voltage electricity used in power lines to the lower voltage used in houses
  3. used in adapters to lower mains voltage to the lower voltages used by many electronic devices
• what type of current is produced in power stations / transferred to homes?

  alternating current (AC)
• what does a basic transformer consist of?

  a primary coil, a secondary coil and an iron core
• why is iron used in the transformer?

  it is easily magnetised