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WJEC Physics

Year 10

Generating Electricity

Shwmae! My name is Mr Ridd

Genrating Electricity 3.2

Fossil Fuel Energy

1. this heat is used to change water into steam in the boiler.
2. the steam drives the turbine - heat to kinetic energy
3. this drives the generator to produce electricity - kinetic to electrical energy.

• Industry set up already to process this energy
• Reliable
• Produce a lot of energy
• Cheap
• Will run out someday – non renewable
• Releases CO₂ and other air pollutants
• New drilling by fracking can cause environmental problems to water and animals in surrounding area.

In a thermal power station fuel such as coal, oil or gas is burned in a furnace to produce heat - chemical to heat energy.

Nuclear Energy

• No CO₂, because nothing gets burned
• Can produce large amounts of electricity from a small amount of fuel
• Reliable
• Very few places in the world where you can do this, as no one wants it on heir doorstep.
• Can be very dangerous if things go wrong
• Waste is radioactive for thousands of years and difficult to dispose of.

• heat is used to change water into steam in the boiler.
• the steam drives the turbine (heat to kinetic energy)
• this drives the generator to produce electricity - kinetic to electrical energy.

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The main nuclear fuels are uranium and plutonium. In a nuclear power station nuclear fuel undergoes a controlled chain reaction in the reactor to produce heat - nuclear to heat energy.

Geothermal Energy – energy from the Earth

1. Cold water is pumped below the ground.
2. Hot rocks heat the water, turning it into steam.
3. The steam is used to generate electricity.

• Renewable
• No CO₂, because nothing gets burned
• Doesn’t damage the environment
• No fuel cost
• Reliable
• Very few places in the world where you can do this
• Costs a lot of money to drill deep into the ground
• Can sometimes releases harmful gases
• Possible earthquake or surface cracking when drilling.

Deep underground, the Earth’s rocks are naturally very hot. We can turn their heat energy into electrical energy to use in our homes – we call this ‘geothermal energy’.

Wave Energy – energy from sea waves

• Renewable
• No fuel cost
• Reliable
• No CO₂, because nothing gets burned

The sea’s waves have kinetic energy. Using machines that bob up and down in the waves, this energy can be turned into electrical energy which we can use in our homes.

• Need lots of machines to get a reasonable amount of energy
• The machines costs a lot of money
• The machines can look ugly
• The machines can be damaged by storms
• Can affect marine life

wave energy machines bobbing up and down in the waves

Hydroelectric Energy – energy from rivers

• Renewable
• No CO₂, because nothing gets burned
• We can store the water up high, and then whenever we need the energy we can let the water out
• No fuel cost
• Reliable
• Immediate response to change in electricity demand
• Cheap

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The water flowing in a river has kinetic energy. We can turn this into electrical energy to use in our homes. We usually need to build a dam, and let the water flow through it gradually.

• Costs a lot of money to build a dam
• The dam can ruin the local environment, because it changes where the water naturally flows. Land flooded behind dam
• Can only be located in suitable places

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Tidal Energy – energy from sea tides

1. At high tide, we trap the water behind a dam.
2. At low tide, the water is released, and its energy is used to generate electricity.

• Renewable
• No CO₂, because nothing gets burned
• Reliable, because there are always two tides every day
• Cheap to run, once it’s built

- Costs a lot to build the dam

- The dam may cause local flooding

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If you’ve ever been to the coast, you may have noticed that the sea level goes up and down, because of tides. When the tide is high, the water has lots of gravitational potential energy, which we can turn into electrical energy to use in our homes.

Solar Energy – energy from the Sun

• Renewable
• No CO₂ or other air pollutants
• No fuel cost
• Easy to install
• Little environmental impact when located on buildings
• Solar cells and solar panels are expensive
• Only works if it’s sunny!

The Earth gets heat and light energy from the sun all the time. Can we use it – yes we can! The Sun’s energy can either be:

1. changed into electrical energy to use in homes, using solar cells;
2. or used to heat water for homes, using solar panels.

Wind Energy – energy from the wind

• Renewable
• No CO₂, because nothing gets burned
• Turbines are quite cheap and easy to build, so they can be used even in poor countries
• Turbines can be ugly and noisy
• Only works if it’s quite windy!
• Can be a threat to birds and bats.
• Can only be located in suitable places
• Requires a large area of land to produce enough energy

Using wind turbines, we can turn the kinetic energy of the wind into electrical energy which we can use in our homes. This is ‘wind energy’.

Biomass Energy – energy from plants (Biofuel)

1. Trees absorb the sun’s energy. The trees change this energy into chemical energy, which they store inside themselves.
2. Other forms of Biofuel include manure, food waste and bioethanol.

• Renewable – as long as we keep planting trees to replace the ones we cut down
• Doesn’t need any special equipment, so it can be used very easily, even in poor countries
• Carbon Neutral. Only releases CO₂ that has already been taken out of the atmosphere by photosynthesis.
• Large areas of land are needed to grow enough trees/plants
• Loss of habitat and space to grow crops due to large amount of land needed.

The chemical potential energy stored in things that were once alive (e.g. trees) can be turned into heat energy by burning them. (We can also turn it into electrical energy to use in our homes.)

Microgeneration

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Energy Resources

Renewable or Non?

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Wind, Solar, Nuclear, Geothermal, Biomass, Fossil Fuels, Wave, Tidal, Hydroelectric.

Vs

Fossil Fuel Power station

Comparing Energy Resources

Vs

Comparing Energy Resources

Vs

Comparing Energy Resources

Generating Electricity 3.2

Fuel based Power Station Demo

Fuel based power station

1. fossil fuels are burnt to heat water in the boiler
2. water is turned into steam in the boiler
3. the steam is under pressure and is used to turn/drive/spin the turbine
4. the turbine turns a generator to generate electricity.

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Boiler

Chemical Heat

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Turbine

Heat Kinetic

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Generator

Kinetic Electrical

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Nuclear Power Station

Nuclear reactor

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Using Uranium and Plutonium fuel rods

Generating Electricity 3.2

Representing an energy transfer

Electrical

Light + sound + heat

TV

260J

60J

A

B

TV Sankey Diagram

Questions

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1. Which type of energy is wasted?

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• Which type is usefully transferred? How do you know?

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• How much energy is usefully transferred?

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• How much energy is wasted?

Efficiency

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What do I see?

What is the Science in this?

When a person buys a new home it will have an energy efficiency rating. Look at the diagram and describe what it tells you.

Question

Look at the Diagrams. They show the Energy transfer for 2 different light bulbs.

1. Which is more efficient and why?
2. By considering the diagrams, what do you think efficiency means?

What is Efficiency?

What does this mean?

This Light bulb has an efficiency of 40%

40% of the energy supplied is turned into useful light

YEH!

X 100

Generating Electricity 3.2

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What is the National Grid?

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Answer - Network of power lines, power stations and transformers that transfer electrical energy around the UK

National Grid

(Transmission)

(Generation)

National Grid Demo

The Role of Transformers in the National Grid

Transformers change the Current and voltage Step up, increases the voltage and decreases the current, and step down transformers decreases the voltage and increases the current for safe use in the home.

It is important to have transformers in the national grid because they improve the efficiency of the National grid so that less energy is wasted as heat when transferring electricity. This is important so that less fossil fuels are burnt, which in turn reduces CO2 emissions and global warming. They also reduces the cost of electricity.

Meeting Demand

Generating Electricity 3.2

Calculating Electrical Power

Stars and the Universe

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WJEC Physics Year 11

Stars and the Universe

Sankey Diagram PPQ