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Sources of Energy. Where does it all come from?. Originally: The sun. Our primary energy source. Provides almost 1,000,000 Joules of energy per square metre of Earth every day. The sun’s energy.
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Sources of Energy Where does it all come from?
Originally: The sun. Our primary energy source. Provides almost 1,000,000 Joules of energy per square metre of Earth every day.
The sun’s energy. • Sunlight is converted to food (chemical energy) by green plants through a process called photosynthesis. • Heat energy from the sun keeps us warm. • The sun heats up the land & sea, which produces wind & waves. • The sun’s heat evaporates water from the sea, which causes rain. • Solar panels & cells capture the sun’s energy directly.
Energy sources can be divided into two groups: • Non-renewable sources – sources that will eventually run out, like fossil fuels.
Energy sources can be divided into two groups: • Renewable sources – sources that won’t run out eventually, like • solar power. • Hydro-electricity. • Wind energy. • Nuclear power. • Tidal and wave energy. • Geothermal energy. • Biomass energy.
Fossil fuels • Oil • Coal • Gas • Turf • Advantages: • Easy to get. • Reasonably cheap. • Disadvantages: • Causing greenhouse gas emissions. • Polluting the atmosphere, • E.g. Acid rain, smog, etc. • Plants make food from sunlight and animals eat them. • When they die, over millions of years, become fossil fuels.
Solar energy Solar energy is taken straight from the rays of the sun. We convert solar energy to electrical energy using solar cells. We also convert solar energy to heat using solar panels.
Solar energy Solar energy is taken straight from the rays of the sun. We convert solar energy to electrical energy using solar cells. We also convert solar energy to heat using solar panels. • Advantages: • It’s free. • It doesn’t cause pollution. • Disadvantages: • Efficiency of solar cells needs to be improved. • Solar cells are expensive to make.
Hydro-electricity By building a dam we store water behind it. This water has potential energy when stored behind the dam. When the water is released it has kinetic energy. This kinetic energy is then converted to electrical energy.
Hydro-electricity By building a dam we store water behind it. This water has potential energy when stored behind the dam. When the water is released it has kinetic energy. This kinetic energy is then converted to electrical energy. • Advantages: • Doesn’t cause pollution. • Cheap way to produce electricity. • Disadvantages: • Flooding can destroy plant & animal habitats. • Building dams can flood valleys where people live.
Wind Energy On a windy day, the moving air has a large amount of kinetic energy. The idea is to change this kinetic energy into electrical energy.
Wind Energy On a windy day, the moving air has a large amount of kinetic energy. The idea is to change this kinetic energy into electrical energy. • Advantages: • Does not cause pollution. • Wind energy is free. • Disadvantages: • No electricity produced on a calm day. • Large propeller masts are noisy & spoil the natural beauty of the countryside.
Nuclear Energy Nuclear fission uses Uranium as a fuel, which will eventually run out, but nuclear fusion only needs water as a fuel. Unfortunately, nuclear fusion technology isn’t available yet.
Nuclear Energy Nuclear fission uses Uranium as a fuel, which will eventually run out, but nuclear fusion only needs water as a fuel. Unfortunately, nuclear fusion technology isn’t available yet. • Advantages: • There’s plenty of water to use as a fuel. • Would reduce greenhouse gas emissions. • Disadvantages: • Danger of nuclear explosion. • Harmful effects of radioactivity.
Other Renewable Energy Sources. • Tidal and wave energy: The kinetic energy of the waves & tide is converted to electrical energy. • Geothermal energy: Heat energy can be trapped under the Earth’s surface. The heat is used to directly heat homes or converted to electricity. • Biomass energy: The oil of fast-growing plants is converted to alcohol and used instead of petrol or to methane, which can be used as a biogas.
Homework. • P. 302, Q. 39.6 – 39.10 • (Information on pages 293 – 294. • Read and prepare pages 295 – 298. • Research: • How many Joules of energy does Ireland use every day?
