P1 - Generating Electricity Flashcards
How is electricity generated in a power station?
Generators are driven my turbines.
Which fossil fuels are burnt in power stations?
Coal, oil and natural gas
Which elements are used as fuel in nuclear power stations?
Uranium or plutonium
What other fuels can be used to generate electricity?
Biofuels such as methane and ethanol
Describe the process of generating electricity in a …-fired power station.
- Burning fuel heats water in a boiler producing steam.
- Steam drives a turbine.
- Turbine turns generator.
Where do fossil fuels come from?
Long-dead biological material.
Where can methane be sourced from?
Animal manure
Decaying rubbish
Sewage works
Where does biofuel come from generally?
Living or recently deceased organisms.
How is biofuel a renewable energy source?
It’s biological source continues to exist and never dies as a species.
How are biofuels carbon-neutral?
The carbon the organism takes in is equal to the CO2 released when burnt.
Explain nuclear fission.
The nucleus of a U-235 atom is split which releases energy.
Explain how energy is transferred to electricity from nuclear fission.
The energy released from nuclear fission heats a coolant which boils water. The steam then turns a turbine.
Give two advantages of nuclear power
- Lots of energy is released
- There are no greenhouse gases
Give two examples of renewable energy.
Hydroelectric and solar (PV)
What is a wind turbine?
An electricity generator at the top of a tower.
How can waves be used to generate electricity?
The movement of the waves turns a generator.
Give three disadvantages of wave power systems.
- Don’t produce a constant supply of electricity.
- Lots of cable needed.
- Can change tidal flow patterns.
How does a hydroelectric plant work?
Water in a reservoir flows downhill, spinning a turbine.
How does a tidal power station generate electricity?
Water is trapped at high tide then released through turbines.
How efficient are current solar cells?
> 10%
Give three disadvantages of PV cells.
- Low efficiency
- Very expensive
- Need lots to generate usable electricity
How do solar power towers generate electricity?
- Computer-controlled mirrors reflect sunlight onto tank.
- The sunlight heats the water and the steam turns a generator.
What is the source of geothermal energy?
Radioactive substances underground.
How is electricity generated from geothermal energy?
- Radioactive substances heat surrounding rocks.
- Water is poured on hot rocks making steam.
- Steam drives a turbine.
How can buildings be directly heated from geothermal energy?
Ground heat warms water in pipes which is pumped around a building.
How do fossil fuels damage the environment?
Burning fossil fuels releases greenhouse gases which contribute to global warming.
Give one concern people might have about nuclear power?
Nuclear fuels produce radioactive waste.
How can renewable energy sources affect the environment?
They can affect animals’ and plants’ habitats.
How is acid rain caused?
Burning fossil fuels can release sulfur dioxide which dissolves in water vapour in the air.
What is a potential problem with sourcing fossil fuels?
Fossil fuels are non-renewable
Give one way of lowering CO2 emissions.
Carbon capture and storage
Give two advantages of nuclear energy.
- No greenhouse gases.
- More energy per kilogram.
Give two disadvantages of nuclear power.
- Used fuel rods contain radioactive waste that has to be stored.
- An explosion would cause disaster over a wide area.
Give four advantages of renewable energy sources.
- They will never run out.
- They don’t produce greenhouse gases or acid rain.
- They don’t produce radioactive waste.
- Can be used in remote areas.
Give four disadvantages of renewable energy sources.
- Wind turbines make noises and “blot” the landscape.
- Tidal barrages affect plant and animal habitats.
- Habitats are often flooded to create dams for hydroelectric.
- Solar cells have to cover a large area.
What is the National Grid?
A network of cables and transformers that distributes electricity.
What do transformers do in the National Grid?
Step-up transformers increase the voltage into the Grid.
Step-down transformers decrease the voltage out of the Grid.
Why are high voltages used in the Grid?
High voltage reduces energy loss making the system more efficient.
What voltage do power stations generate electricity at?
25,000V (25kV)
What is the voltage of the Grid?
132kV +
What voltage do home appliances take from a plug socket?
230V
Why does a higher voltage make the Grid more efficient?
As the voltage is higher, the current is lower. This reduces the heat energy transferred that is caused by the current.
What type of power stations are used to meet variations in demand for electricity?
Gas-fired power stations as well as pumped storage charged by renewable energy sources.
What power stations are used to meet base-load demand?
Nuclear, coal and oil power stations.
Why are gas fired power stations used to meet variations in demand?
They can be started up instantly.
What happens when there is less demand than the base-load?
Energy is stored for when demand is above base-load.
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