Physics - P1.4 - Generating Electricity - Revision Cards in GCSE Physics

P1.4.1 - Fuel for Electricity

Most power stations - water heated to produce steam -> steam drives a turbine, coupled to an electrical generator that produces electricity
Energy from burning fossil fuels - long-dead biological material
Some gas-fired power stations - hot gas power drive turbine - switched on/off quickly
Biofuel - fuel obatained from (recently) living organisms - used in small scale gas-fired power stations - renewable
Nuclear power station - uranium(/plutonium) used as fuel - uranium atom can undergo nuclear fission - releases lots of energy - lots of uranium nuclei = lots of fission reactions - energy used to heat water -> steam
Energy released/kg in nuclear power station > energy released/kg in gas-fired power station
Nuclear power stations - no greenhouse gases, radioactive waste

1 of 7

Renewable energy - never be used up
Use energy from wind and water to drive turbines directly
Wind - wind passes over blades -> rotate -> drive generator
Water - obtained from falling water, waves or tides, hydroelectric power - water collected in a reservoir -> water flows downhill -> turns turbines -> times of low demand, surplus electricity used to pump water back to top - energy is stored
Wave - movement of waves on sea used to generate electricity - movement drivesfloating turbine -> turns generator -> electricity delivered to grid system by onshore cable
Tidal - barrage built across river estuary -> water at high tide trapped behind it -> released to fall to lower sea -> drives turbines

2 of 7

Solar energy - travels from sun to earth as electromagnetic radiation
Solar cell - transfer sun energy -> electrical energy, each cell only produces small amount of energy - useful to power small devices (eg. watches, calculators), can join large numbers together to form solar panel
Water heated directly by sun as it flows through solar heating panel
Solar power tower - uses thousands of mirrors to reflect sunlight onto water tank to heat water -> steam
Geothermal energy - produced instide the earth by radioactive processes - heats surrounding rock - in volcanic areas, deep holes drilled -> cold water pumped down to hot rocks -> heated -> returns to surface as steam -> drive turbines that turn generators
In few parts of the world - hot water comes to surface naturally - used to heat nearby buildings

3 of 7

Coal, oil, gas and uranium - non-renewable - rate they are being used > rate they are being produced
Oil and gas - run out in ~50 years, coal will last longer
Renewable energy sources - won't run out - can be produced as fast as they're used
Scientists investigating ways to reduce environmental impact of using fossil fuels - eg. sulfur removed from fuel before burning, capturing CO2 and storing in old oil and gas fields, instead of releasing it into atmosphere

4 of 7

Coal - bigger reserve, reliable, non-renewable, produces CO2 and SO2
Oil - reliable, non-renewable, produces CO2 and SO2
Gas - reliable, non-renewable, produces CO2
Nuclear - no polluting gases, reliable, non-renewable, hazardous nuclear waste, (small) risk of nuclear accident
Wind - renewable, no polluting gases, free, requires turbines, not reliable
Falling water - renewable, no polluting gases, free, reliable where wet, only works in certain areas, damming - floods and affects local ecology
Waves - renewable, no polluting gases, free, reliable, few suitable areas, building barrages affects local ecology
Solar - renewable, no polluting gases, free, reliable, need many solar cells
Geothermal - renewable, no polluting gases, free, economically viable in few places, drilling is difficult and expensive

5 of 7

National Grid - dristributes electricity in Britain, network of pylons and cables that connect power stations to homes, schools, factories and other buildings, whole country connected - power stations switched in/out of grid according to demand
Cables carried over long distances in countryside, supported by overhead pylons, in towns - cables buried underground
National Grid voltage - 132000V, power station electricity - 25000V
Step-up transformers - increase voltage before electricity is transmitted across National Grid - transmission at high voltage = decreased wasted energy = efficient system
Step-down transformers - reduces voltage (230V) to be sent into homes - dangerous to supply electricity at high voltages

6 of 7

Constant amount of electricity provided by nuclear, coal- and oil-fired power stations - base load demand
Electricity demand varies over summer and winter (heating)
Variable demand met using gas-fired power stations, pumped storage schemes and renewable energy resources
Low demand - energy stored by pumping water to top of reservoir of pumped storage schemes
Start up times - different for each power station - gas-fired have shortest -> oil -> coal -> nuclear power stations have longest

7 of 7