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Learn about different types of energy, how energy can be converted from one form to another, and the importance of renewable energy sources. Discover the environmental effects of burning fossil fuels and explore alternative energy options.
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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. 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.
Different types of energy There are many different types of energy: • thermal • light • sound • elastic • gravitational • kinetic • electrical • chemical • nuclear Can you think of examples of each type of energy?
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.
Energy resources from the Sun coal oil wind biomass natural gas food The energy in all these energy resources originated from the Sun.
Non-renewable energy resources oil coal gas Oil, coal and natural gas are examples offossil fuels. They were formed from biological deposits over the course of millions of years. 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.
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.
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. Oil wells drilled at sea are supported by oil platforms.
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. Carbon dioxide is a greenhouse gas.
300 250 200 Years left 150 100 50 0 Coal Oil Gas Why are alternatives to fossil fuels needed? Burning fossil fuels has many bad effects on the environment. 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.
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 Only 4% of the UK’s energy comes from renewable sources.Why do you think this is?
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. Mirrors can be used to focus sunlight onto pipes containing water. The hot water drives a generator.
Other renewable energy sources What other forms of renewable energy are there? Geothermalenergy 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. Wavescan generate electricity by causing buoys to rise and fall. This kinetic energy is converted to electrical energy.
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.
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.
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 generator nuclear reactor Unfortunately, fission reactions create dangerous radioactive waste products. Is nuclear energy renewable?
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.
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.
