Generating Electricity Flashcards
How do most power stations work?
- Water is heated to produce steam
- The steam drives a turbine, which is coupled to an electrical generator.
- This generator converts the kinetic energy to electrical energy and thus generates electricity
How are fossile fuels obtained/what are they?
Long-dead biological material that has been compressed under high pressure to form carbon compounds. Obtained by drilling/mining (coal)
How do gas fire power stations and hyroelectric (HEP) power stations differ from the standard power station model?
In gas-fired power stations, the hot gas drives the turbin directly.
In HEP, the water drives the turbin (grav. potential -> kinetic -> electric)
What is burned in fossil-fuel powered power stations?
Coal, oil, and gas
What is used as fuel in a nuclear power station?
Uranium or plutonium
What is a biofuel?
A fuel obtained from living or recently living organisms
What type of energy source are biofuels?
Renewable
Where does the energy required to drive the turbines/produce steam come from in a nuclear power station?
Not from burning uranium/plutionium!
- The nucleaus of a uranium atom can undergo nuclear fission, releasing thermal energy (and other waste energy)
- There are lots of uranium nuclei, so lots of fission reactions take place, releasing lots of energy
- This energy is used to heat water, turning it into steam which drives the turbine
Complete the sentence:
Biofuels can be used in…
…small-cale, gas-fired power stations
Which releases more energy per kilogram of fuel burnt:
Uranium undergoing fission OR fossil fuels being burnt?
Uranium undergoing fission - it has a higher fuel density per kg
Nuclear power stations do not release any…
…greenhouse gasses, unlike fossil-fuel power stations
What do nuclear power stations produce that other power stations don’t?
Radioactive waste
What are the negatives of radioactive waste
- It’s radioactive
- It must be safely stored for a long period of time
- It can be used to make nukes (which can be bad… depening on your views)
Draw and label a diagram of a fossil-fuel powered power station
Define ‘renewable energy’
Energy from sources that never run out (or will run out in a very, very long time)
How can wind be used to generate electricity?
- Can be used to drive turbines directly
- In a wind turbine, the wind passing over the blades makes them rotate and drives a generator at the top of a narrow tower
What methods of generating electricity use water?
Electricity can be produced from energy obtained from:
- Falling water - HEP
- Waves - Wave power
- Tides - Tidal power
How does HEP work?
- At a HEP, water is collected in a reservoir.
- This water is allowed to flow downhill and turn turn turbines at the bottom of the hill
- In a pumped storage system, surplus electricity is used at times of low demand to pump the water back up the hill into the reservoir
- This means the energy is stored
- At times of high demand, the water can be released to fall through the turbines and transfer the stored grav. pot. to kinetic, and then to electical energy.
How is wave power used to generate electricity?
- We can use the movement of the waves on the sea to generate electricity
- The movement drives a floating turbine that turns a generator.
- Then, the electricity is delivered to the grid system on shore by a cable
How is tidal power used to generate electricity?
- The level of sea around the coastline rises and falls twice each day
- These changes in sea level are called tides (crazy)
- If a barrage is built across a river estuary, the water at each high tide can be trapped behind it
- When the water is released to fall down to the lower sea lever, it drives turbines.
N.B. This works a bit like HEP, except instead of pumping/releasing water from a reservoir, the tides naturally raise the water level and it can then be released.