Name some energy types and an example?
Kinetic – Walking
Thermal – Sun
Gravitational Potential – A raised apple
Chemical – Food
Sound – Sound waves
Electrical – Electricity in a phone
Elastic Potential – Bungee
Nuclear – Nuclear fission
Radiant – EM from the Sun (used in eV)
What is the conservation of energy?
Total energy in = Total energy out
E in = E out
Energy cannot be created or destroyed, merely transformed from one form to another
How does a simple wind turbine work?
Wind flows and the particles in the air hit the turbine’s blades. The number of collisions is so vast a substantial force can be exerted
The blades are designed so that these collisions cause them to rotate in one direction
Inside the turbine, in a nacelle, the blades turn a low-speed shaft which a gearbox increases the RPM of so a high-speed shaft turns a generator and produces electricity. This can be used locally or exported to the National Grid
What is the UK’s power production mix?
2018/19 - 42% of electricity was produced using natural gas, 18% by nuclear energy and 5% by coal. Then the rest was made up by 18% wind and 6% biomass
Coal was completely phased out by the UK by 2025 and are currently quite reliant on natural gas imports
Describe stage 1 of the generation of electricity in a fossil fuel power plant?
Combustion of the fossil fuel
The fuel is combusted in a furnace to release chemical energy that it contains → thermal energy
Describe stage 2 of the generation of electricity in a fossil fuel power plant?
Evaporation of water
The thermal energy is used to increase the temperature of the water in the furnace, increasing the temperature of the cold water to about 100°C. It evaporates to steam. This steam is ejected from the furnace and directed into the steam turbine
Describe stage 3 of the generation of electricity in a fossil fuel power plant?
Steam used to turn a turbine
The steam turbine turns when the high-pressure steam is forced through it. Steam, which is extremely high velocity water molecules, collides with the fins of the steam turbine causing the turbine to turn
The steam molecules have less energy after each collision. Hence the steam which is entering the steam turbine at its hottest temperature leaves at a lower temperature, but is still hot. The hot steam is now sent to the cooling towers
Describe stage 4 of the generation of electricity in a fossil fuel power plant?
Condensing in the cooling towers
The steam loses energy as it condenses back to a liquid. Then the liquid, which is colder, is circulated back to the furnace and the process is repeated
Issues with the cooling towers in a fossil fuel power plant?
The cooling towers take considerable energy from the steam and eject it to the atmosphere, reducing overall efficiency
Efficiency fluctuates around 40%. CHP is used to prevent this
What are Direct Renewable Energy Sources?
These renewable energies take energy from a renewable source such as wind or waves in the ocean and can convert this into electrical energy directly
Eg: Wind, hydroelectric, wave & tidal
What are Indirect Renewable Energy Sources?
These take energy from a renewable source such as the Sun using a physical characteristic of the material being used and convert this energy into electrical energy
Eg: Solar PV and Biomass
Explain in the E.M Induction in the Generator?
A metallic conductor rotates when the steam turbine rotates as they are connected to a common shaft.
Strong magnets are placed around the metallic conductor so when it rotates the magnetic field lines are cut and an induced current flows, producing electricity
Energy changes in wind?
Wind → Hub → Gearbox → Generator
KE of wind → KE of blades/hub & main shaft → KE of high-speed shaft → Electrical energy
↓ Thermal and sound losses
↓ Thermal and sound losses
↓ Thermal and sound losses
Energy changes in Hydroelectric?
Dam → Moving water → Turbine → Generator
GPE → KE → KE as it rotates → Electrical energy
↓ Thermal & sound losses
↓ Thermal & sound losses
↓ Thermal & sound losses
Energy changes in Solar?
Sun → PV panel
Radiant energy → Electrical energy
↓ Thermal losses
Describe the operation of hydroelectric?
The Sun evaporates water which rises and then condenses to form clouds. As it cools it forms rain which can be collected in high mountainous areas. Rivers can be blocked off to create a large depth of water behind a dam
A door can be opened inside the dam’s turbine shaft allowing water to flow down. As the water travels it turns a generator producing electricity
Describe the operation of tidal?
The gravitational attraction of the moon causes the oceans’ water levels to rise and fall. When the tide comes in through a barrage, the gates along the barrage can be shut at high tide
Maintaining the high water level in the estuary so as the tide returns to its low level again the gates may be opened and the water flows through the turbine shafts to produce electricity
Energy changes in tidal?
Behind tidal barrier → Moving water → Turbine → Generator
GPE → KE → KE as it rotates → Electrical energy
↓ Thermal & sound losses
↓ Thermal & sound losses
↓ Thermal & sound losses
Describe the operation of wave power?
Land rises in temperature faster than water and gains more energy from the sun. Giving the air above land more energy and making it rise, the cooler sea air rushes in to fill this space pushing wind from the ocean to land
The wind rubs against the surface of the water producing waves, causing tubes of a wave generator to oscillate up and down. This causes fluid to flow at the joints between tubes which causes a generator to turn producing electricity
Energy changes of waves?
Sun → Waves → Wave generator → Generator
Radiant energy from the Sun produces wind → KE of wind causes KE of waves → KE of tubes on the surface to gain KE → Electrical energy
↓ Thermal & sound losses
↓ Thermal & sound losses
Energy changes of biomass?
Biomass (fuel) → Burning fuel → Steam → Turbine → Generator
Chemical energy → Thermal energy → Thermal energy → KE → Electrical energy
↓ Thermal losses
↓ Thermal & sound losses
↓ Thermal & sound losses
Describe stage 1 of how the national grid transmits energy?
Electricity is generated in a power station and is at 22 kV or 22,000 V.
Describe stage 2 of how the national grid transmits energy?
Steps up the voltage from 22 kV to somewhere in the 275–400 kV range.
The huge increase in voltage results in a huge decrease in current.
This minimises the heat losses occurring in the cables maintaining a high efficiency.
Describe stage 3 of how the national grid transmits energy?
Materials with low resistance are used to minimise energy losses & the electricity is sent along the national grid at 275–400 kV.
