3. What is energy?

4. What is energy?
Energy can be defined as the ability to do work. It exists in many forms and can be changed from one form to another.
For example:
Chemical energy in food is converted to thermal energy and kinetic energy by our bodies.
Gravitational potential energy in a ball is converted to kinetic energy when it falls to the ground.
Photo credit: © 2008 Jupiterimages Corporation
What other energy transfers can you think of?
In all these transfers the energy is not lost, it is conserved. Energy cannot be destroyed or created.

5. Different types of energy
There are many different types of energy:
thermal
light
sound
elastic
gravitational
kinetic
electrical
chemical
nuclear
Photo credit: © 2008 Jupiterimages Corporation
Can you think of examples of each type of energy?

6. Different types of energy

7. Converting energy
Energy Resources Worksheet 1 accompanies this slide

9. Energy and the Sun
The Sun is the original source of most energy resources.
Plants store the Sun’s energy through photosynthesis.
leaf
caterpillar
bird
fox
Plants are eaten by animals, which are then eaten by other animals, so the energy is passed on.

10. Energy resources from the Sun
The energy in all these energy resources originated from the Sun.
coal
oil
wind
biomass
natural gas
food

11. Non-renewable energy resources
Oil, coal and natural gas are examples of fossil fuels. They were formed from biological deposits over the course of millions of years.
gas
oil
coal
Photo credit: © 2008 Jupiterimages Corporation
The amount of fossil fuel on Earth is limited. Once fossil fuels are used they cannot be replaced and will eventually run out, so they are called non-renewable.

12. Coal formation

13. Early stages of oil and gas formation
Oil and gas are also biological in origin. Millions of years ago, tiny animals lived in the sea. Like today, their ecosystem was dependent on heat and light from the Sun and photosynthesis by plants.
When they died, the animals fell into mud and sand at the bottom of the sea, but did not rot away.
Over millions of years they were buried deeper by the mud and sand.

14. Later stages of oil and gas formation
The temperature and pressure (caused by the weight of the sediments and deep burial) changed the mud and sand into rock, and the dead animals into crude oil and natural gas.
The oil and gas is extracted from the seabed or under the ground, by drilling oil wells.
Photo credit: © 2008 Jupiterimages Corporation
Oil wells drilled at sea are supported by oil platforms.

15. Fossil fuels summary

16. Generating electricity from fossil fuels

17. Labelling parts of a power station

18. How is electricity generated?

19. Environmental effects of burning fossil fuels
Using fossil fuels to produce electricity has consequences for the environment.
Burning some fossil fuels creates chemicals like sulfur dioxide, which cause acid rain.
Burning fossil fuels also produces carbon dioxide which is released into the atmosphere.
Photo credit: © 2008 Jupiterimages Corporation
Carbon dioxide is a greenhouse gas.

20. Environmental effects of burning fossil fuels

22. Why are alternatives to fossil fuels needed?
Burning fossil fuels has many bad effects on the environment. 50
100
150
200
250
300
Coal
Oil
Gas
Years left
However, environmental damage is not the only problem with continuing to rely on fossil fuels to supply our energy needs.
What does this chart show?
Governments and scientists are trying to develop alternative sources of energy to replace fossil fuel power stations.

23. What are renewable energy sources?
Renewable energy resources will not run out because they can easily be generated anew. The photograph shows a dam built for the generation of hydroelectric power.
Other examples of renewable energy resources are:
wind power
solar power
tidal power
biomass
Photo credit: © 2008 Jupiterimages Corporation
Only 4% of the UK’s energy comes from renewable sources. Why do you think this is?

24. How can the wind generate electricity?

25. How is solar energy used?
There are a number of methods of generating electricity from the Sun’s energy.
Passive solar heaters heat water directly using sunlight. Why are they black?
Solar panels convert sunlight into electricity directly. They are used on some new houses and also on calculators.
Photo credits: © 2008 Jupiterimages Corporation
Mirrors can be used to focus sunlight onto pipes containing water. The hot water drives a generator.

26. Other renewable energy sources
What other forms of renewable energy are there?
Geothermal energy uses heat stored beneath the Earth’s surface to create steam. This is then used to power turbines.
Biomass fuels are made of processed plant remains and are used in the same way as fossil fuels. More crops are grown to replace those used.
Tidal currents can be used to generate electricity. The moving water is forced through turbines, which generate electricity.
Waves can generate electricity by causing buoys to rise and fall. This kinetic energy is converted to electrical energy.

27. Other renewable energy sources

28. Renewable energy: summary
Energy Resources Worksheet 2 accompanies this slide.

29. Comparing fuels
How can we compare the energy content of renewable and non-renewable fuels?
Choose some different fuels, such as wood and methylated spirits. Set up the apparatus as shown in the diagram.
Weigh each of the fuels.
Place one of the fuels in the container or spirit burner, light with the match, then record the maximum temperature reached by the water.
Repeat for each of the types of fuel.

31. Energy from atoms
Albert Einstein is perhaps the most famous physicist of all time. He first came up with the idea of getting energy from atoms.
Scientist found that large amounts of energy could be produced by a process known as fission, which involves splitting atoms of uranium.
Towards the end of the Second World War, the USA dropped two uranium bombs on Japanese cities – the effects were devastating.
Photo credit: © 2008 Jupiterimages Corporation

32. Nuclear energy
Nuclear power stations use fission in a controlled way to generate electricity.
The process is similar to that used to generate electricity from fossil fuels.
national grid
turbines
boiler
Teachers Notes
Nuclear energy is not renewable as there is only a finite amount of Uranium in the world. However, uranium supplies are likely to last a long time because only a small amount is required by a reactor.
generator
nuclear reactor
Unfortunately, fission reactions create dangerous radioactive waste products. Is nuclear energy renewable?

33. Nuclear fusion
Fusion (joining atoms) is the opposite idea to fission (splitting atoms). The Sun and all other stars are powered by fusion reactions.
Fusion produces no harmful waste and generates enormous amounts of energy.
Unfortunately, it needs very high pressures, and temperatures as hot as the sun to get it started.
Photo credit: EFDA-JET Interior of the JET vacuum vessel.
JET is the largest nuclear fusion experimental reactor. It is located in Culham, Oxfordshire.
More information about the JET fusion reactor is available at

34. New ways of generating useful energy
Hydrogen is now being used to power cars in California, where you can fill up with the gas just like petrol. It is converted by the car’s fuel cells into water and electricity.
At present however, the production of hydrogen is expensive and often requires a lot of energy.
Methane is a waste product from animals and from rotting plant and animal material.
The gas can be collected and burned in a power station.
Photo credit (cows): © 2008 Jupiterimages Corporation
Photo credit (car): © BMW AG 08/2006. For press purposes only.
Photo shows BMW Hydrogen 7 – Winter 2006.
P BMW Group PressClub.

35. Energy sources for the future

37. Glossary
biomass – Energy stored inside living or once-living materials such as wood.
energy – The ability to do work. It exists in different forms such as chemical, electrical, heat and light.
fission – The splitting of atoms, usually of uranium. Used to generate electricity in nuclear power stations.
fossil fuel – A fuel such as coal, oil and gas that forms from animal and plant matter over millions of years. The world's supply of fossil fuels is running out fast.
fuel cell – A device that reacts hydrogen with oxygen to produce water and electricity.
fusion – The joining of atoms. These reactions power the Sun and could be used to generate electricity in the future.
geothermal – Using the heat inside the earth to warm water or produce steam.
greenhouse effect – The warming of the earth caused by greenhouse gases in the atmosphere trapping the Sun's energy.
hydrogen – Fuel which can be used to power cars. The gas is converted to electricity and water by fuel cells.
methane – Natural gas. It can be extracted from deep underground or produced by the decomposition of plant and animal remains. It is also produced in the guts of animals.
nuclear energy – Energy stored inside atoms, which are the building blocks of everything around you.
renewable – An energy resource that can be replaced and will not run out.
solar energy – Energy obtained from the Sun.

38. Anagrams

39. Multiple-choice quiz