4.17 describe the advantages and disadvantages of methods of largescale electricity production from various renewable and nonrenewable resources.

Fossil fuels: non renewable; release CO2.

Burning wood: renewable; release CO2; destroy habitats.

Wind power: visual pollution; produces small amounts of electricity for space and effort in comparison to other methods.

HEP: expensive to set up; limited places to put it; can kill fish.

Solar cells: rely on the weather.

Nuclear power: dangerous; many waste products.

There are many more types of power and fors/againsts but these are a few important ones.

4.16 describe the energy transfers involved in generating electricity using several different methods

• wind- the kinetic energy from the wind, turns a turbine which turns a generator which produces electrical energy
• water- Kinetic energy from water, turns a turbine which turns a generator which produces electrical energy
• geothermal resources- Thermal energy heats water, water turns into steam, the thermal energy of the steam turns a turbine which then has kinetic energy, the turbine turns a generator which produces electrical energy
• solar heating systems- Light energy from the sun into thermal energy in water
• solar cells-convert light energy from the sun into electrical energy
• fossil fuels- Chemical energy is burnt to form heat energy, this turns into heat energy in water, this turns into kinetic energy in a turbine, this turns into electrical energy in a generator.
• nuclear power- kinetic energy in uranium, heat energy in water, kinetic energy in turbine, electrical energy in generator.

Energy resources

•Renewable source of energy: is inexhaustible, for example solar, hydroelectric, wind etc.
•Non-renewable source of energy: is exhaustible for example fossil fuels
•fuels can be burnt (or nuclear fuel can be forced to decay) in thermal power stations to transform the chemical energy stored to thermal energy which makes steam which turns turbines (kinetic energy) to produce electricity.
-advantage: cheap, plentiful, low-tech
-disadvantage: harmful wastes -produces greenhouse gases and pollutant gases, radiation...
•hydroelectric dams: river and rain water fill up a lake behind a dam. As water rushes down through the dam, it turns turbines which turn generators.
•tidal power scheme: a dam is built across a river where it meets the sea. The lake behind the dam fills when the tide comes in and empties when the tide goes out. The flow of water turns the generator.
 -advantage: no greenhouse gases are produced
 -disadvantage: expensive, can’t be built everywhere
•wave energy: generators are driven by the up and down motion of the waves at sea.
 -advantage: does not produce greenhouse gases
 -disadvantage: difficult to build
•geothermal resources: water is pumped down to hot rocks deep underground and rises as steam.
 -advantage: no carbon dioxide is produced
 -disadvantage: deep drilling is difficult and expensive
•nuclear fission: uranium atoms are split by shooting neutrons at them.
-advantage: produces a lot of energy from using very little resources
-disadvantage: producing radioactive waste
•solar cells: are made of materials that can deliver an electrical current when they absorb light energy •solar panels: absorb the energy and use it to heat water
-advantage: does not produce carbon dioxide
 -disadvantage: variable amounts of sunshine in some countries