Chapter 4 - Generating Electricity Flashcards
How is energy released from uranium
Nucleus of uranium undergoes nuclear fission
Advantage and disadvantage of nuclear power stations compared to fossil fuel power stations
Advantage:
•Much more energy is released per kg or ur soul undergoing fission reactions that from each kg of fossil fuel burnt
•Nuclear power stations do not release any greenhouse gases
Disadvantage:
•Nuclear power stations produce radioactive waste that must be stored for a long period of time
What fuel is used in nuclear power stations
Uranium
What is a biofuel
A fuel obtained from living or recently living organisms. They are renewable resources
What process does the nucleus of a uranium atom undergo
Nuclear fission
How does a wind turbine work
Wind passing over blades makes them rotate and drives a generator at the top of the tower
How does hydroelectric power work
At hydroelectric power station, water is collected in a reservoir. Water is allowed to flow downhill and turn turbines at bottom of hill.
What happens in a pumped storage system
At times of low demand surplus energy is used to pump the water back up the hill to the top of the reservoir. This means energy can be stored. Then at times of high demand the water can be released to fall through the turbines and transfer the stored energy to electrical energy
How does wave power work
Movement of waves drives a floating turbine that turns a generator. Electricity is delivered to the grid system on a shore by a cable.
How does tidal power work
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 level, it drives turbines
What does solar energy travel as
Electromagnetic radiation
What does a solar cell do
Transfer solar energy into electrical energy
How does a solar power tower work
Uses thousands of mirrors to reflect sunlight onto a water tank to heat the water and produce steam
How is geothermal energy produced
It is produced inside the earth by radioactive processes and this beats the surrounding rock. In volcanic or other suitable areas, very deep holes are drilled and cold water is pumped down to the hot rocks. There it is heated and comes back to the surface as steam. The steam is used to drive turbines that turn generators and electricity is produced
How could carbon dioxide be captured so that it isn’t released into the atmosphere
Storing it in old oil and gas fields
What are the disadvantages of nuclear energy
It produces hazardous nuclear waste, which is difficult to dispose of safely
There is also a small risk of a big nuclear accident
What are the disadvantages of wind power
Requires many large turbines
Not reliable as wind does not always blow
What are the disadvantages of falling water
Only works in wet and hilly areas
Damming the areas causes flooding and affects local ecology.
What are the disadvantages of wave power
Can be hazardous to boats
What are the disadvantages of solar power
Solar cells only produce a small amount of electricity
Unreliable
What are the disadvantages of tidal power
Only a few river estuaries are suitable
Building a barrage affects the local ecology
What are the disadvantages of geothermal energy
Only economically viable in very few places
Drilling through a large depth of rock is difficult and expensive
What are the disadvantages to all renewable sources
They are unreliable (apart from tidal)
What are the advantages of overhead cables compared to underground cables
They are easier to repair and are cheaper
What is the mains voltage in homes
230V
Why are step up transformers used
Because transmissions at high voltage reduces the energy wasted in the cables, making the system more efficient.
Why are step down transformed used
To reduce the voltage to 230 V for use in homes and offices as supplying electricity to consumers at very high voltages would be dangerous.
What is the base load demand
The constant amount of electricity provided by nuclear, coal fired and oil fired power stations.
