Generating electricity

• what is renewable energy resource

  energy source which can be replenished as it is being used up
• 4 examples of renewable energy

  . wind energy

  . hydro electricity

  . tidal energy

  . solar energy
• example of non renewable energy

  fossil fuels
• advantages of generating power using gas rather than coal

  . flexible generation - gas power stations have short start up times so can be switch on or off more readily

  . lower emissions of carbon dioxide
• 2 disadvantages of using renewable energy to generate power

  . output often determined by external factors (wind speed) so supply in uncertain

  . generating power through other means is often more efficient
• environmental impacts of burning fossil fuels

  . carbon dioxide contributes to the greenhouse effect, causes global warming

  . sulphur dioxide leads to acid rain, which damages buildings and crops
• 3 advantages of fossil fuels as an energy resource

  . reliable - not dependent so can generate power anytime

  . can produce large amounts of energy for a given quantity

  . still relatively abundant, so cost effective
• 3 advantages of nuclear power

  . very large quantity of energy for relatively small quantity of fuel

  . doesn't release greenhouse gases

  . low fuel costs
• 3 disadvantages of nuclear power

  . produces nuclear water which is harmful to humans

  . nuclear fuel is non renewable energy source
• social factors acts as a deterrent for certain types of energy production

  . visual pollution

  . sound pollution
• 2 types of transformed

  . step up transformers

  . step down transformers
• where are step up transformers found in national grid what do they do

  . used when connecting power stations to transmission cables

  . they increase the potential difference (decreasing current)
• where are step down transformers found in national grid what do they do


  . used when connecting transmission cables to homes

  . decrease potential difference increasing current
• why do transmission lines transfer electricity at high potentials

  . high potential difference results in low current

  . the lower the current, less energy is dissipated as heat

  . transport is more efficient
• why does potential need to be decreased between transmission lines and houses

  . lower potentials are safer for domestic use and reduces of electrocution

  . household appliances are designed for 230V
• 2 equations to calculate effiency

  e = useful output energy ÷ total input energy

  e = useful output energy ÷ total power output