Flashcards in P1 4 Nuclear And Fossil Fuels Deck (25)
What is burned in a fossil fuel powered station?
Coal, oil and natural gas are burned in fossil fuel power stations.
What are the fuels used on a nuclear power station?
Uranium or plutonium are the fuels. Much more energy is released per kg of uranium or plutonium than from fossil fuels.
What are biofuels?
Biofuels are renewable sources of energy. Biofuels such as methane and ethanol can be used to generate electricity.
Characteristics of biofuels:
Renewable, its biological source continues to exist and never dies out as species.
Carbon neutral, the carbon it takes in for respiration as carbon dioxide is balanced by he amount released when it is burned.
How is electricity obtained from a nuclear power station?
The nucleus of either plutonium or uranium is unstable and it can split into two. Energy is released as this happens. This is called nuclear fission since the uranium atoms in the core become very hot.
The energy of the core is transferred to the coolant which is pumped through the core. The energy of the coolant is used to turn water to steam in the heat exchanger. This steam drives a turbine which turns electricity generators.
Nuclear power advantages and disadvantages
•Has radioactive waste
•An explosion at a nuclear reactor can cause radioactive materials to spread over wide areas.
•No greenhouse gases
•Lots of energy released per kg
Fossil fuel power advantages and disadvantages
Less energy released per kg than nuclear fuels
Fossil fuels produce gases such as CO2 when they burn which contribute to global warming
Can also produce sulphur dioxide when burned which leads to acid rain
Non-renewable, soon enough alternative sources need to be found.
No radioactive waste
More energy released than renewable sources
A much more reliable source of energy than renewable sources.
What is a wind turbine?
An electricity generator on top of a tall tower.
How do waves generate electricity?
By turning a floating generator.
How do hydroelectric sources generate electricity?
The generators are turned by water running downhill. Rainwater is collected in a reservoir and then it flows downhill. This flowing water drives turbines that turn electricity generators at the foot of the hill. The water is then pumped back up.
How do tidal power stations generate electricity?
The station traps each high tide and uses it to turn generators.
What are solar cells?
Solar cells are flat solid cells that convert solar energy directly into electricity.
What are solar heating panels?
Solar heating panels use the sun's energy to heat water.
Where does geothermal energy come from?
Geothermal energy comes from the energy released by radioactive substances deep inside the earth. Geothermal energy is energy from hot rocks.
How does a geothermal power station work?
Water is pumped into hot rocks underground which turns the water to steam. The steam is collected and used to drive turbines which generate electricity.
Renewable energy advantages and disadvantages
•They will never run out
•They don't produce greenhouse gases or acid rain
•They don't create radioactive waste products
•They can be used where connection to the National Grid is uneconomic, Eg: road signs
•Wind turbines create a whirring noise that upsets people nearby and some people think they are an eyesore
•Tidal barrages affect river estuaries and the habitats of creatures and plants there
•Hydroelectric schemes need a lot of water which can affect nearby animal and plant life. Habitats are often flooded to create dams
•Solar cells would need to cover large areas to generate large amounts of power
What is The National Grid?
The National Grid is a network of cables and transformers that distributes electricity to our homes from distant power stations and renewable energy generators.
What do step-up transformers do?
Step-up transformers are used to step-up power station voltages to the grid voltage so less current is needed to transfer the same amount of power.
They raise the voltage and lower the current.
What do step-down transformers do?
Step-down transformers are used to step the grid voltage down for use in our homes. This reduces energy loss in cables.
They lower the voltage and raise the current.
What does a high grid voltage do?
A high grid voltage reduces energy loss in the cables and makes the system more efficient.
Underground cables advantages and disadvantages
•Overhead cables spoil the landscape
•Electric currents produce electric and magnetic fields that could affect people from overhead pylons.
•Overhead pylons could be damaged by extreme weather.
•Much more expensive to implement
•Difficult to repair/ maintenance
•Difficult to bury where they cross canals, bridges and roads
•Underground cables are closer to people so they could affect them more
Power stations' start up times
Natural gas, oil, coal, nuclear
Unreliable renewable energy
Hydroelectric- upland reservoir could dry.
Wind, waves- wind and waves are too weak on very calm days.
Tidal- height of tide varies both on a monthly and yearly cycle.
Solar- no solar energy at night and variable during the day.
How is the demand for electricity met?
Nuclear, coal and oil-fired power stations provide a constant supply, this is called the base load demand.
When there is extra demand, gas and pumped storage schemes are used.
When demand is high, renewables are used and when conditions are met: Eg- a very windy day, wind turbines are used.
When demand is very low, renewable energy is used.