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science PRESENTATION ENERGY RESOURCES. The sun is 75% hydrogen. It releases energy by a process called nuclear fusion, in which the nuclei of hydrogen atoms are pushed together to form helium. The energy resources we use on Earth can be renewable or non-renewable.
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The sun is 75% hydrogen. • It releases energy by a process called nuclear fusion, in which the nuclei of hydrogen atoms are pushed together to form helium.
The energy resources we use on Earth can be renewable or non-renewable. • For example, wood is a renewable fuel. Once used, more can be grown to replace it. • Oil, on the other hand, is non-renewable. It took millions of years to form in the ground, and cannot be replaced.
FOSSIL FUELS • Coal, oil, and natural gas are called fossil fuels because they formed from the remains of plants and tiny sea creatures that lived millions of years ago. • They are a very concentrated sources of energy.
Oil is especially useful because petrol, diesel, and jet fuelcan be extracted from it. • It is also the raw material from which most plastics are made.
When the fuels burn, their waste gases pollute the atmosphere. • Probably the most serious concern is the amount of carbon dioxide produced. • This may be adding to global warming.
NUCLEAR FUELS • Most contain uranium. • 1 kg of nuclear fuel stores as much energyas 55 tones of coal. • In nuclear power stations, the energy is released by fission, a process in which the nuclei of uranium atoms are split.
High safety standards are needed. • The waste of from nuclear fuel is very dangerous and stays radioactive for thousands of years. • Nuclear power stations are expensive to build, and expensive to decommission.
HYDROELECTRIC ENERGY • A river fills a lake behind a dam. • Water flowing down from the lake turns generations. • Expensive to build. • Few areas of the world are suitable. • Flooding land and building a dam causes environmental damage.
TIDAL ENERGY • Similar to hydroelectric energy, but a lake fills when the tide comes in and empties when it goes out. • As for hydroelectric energy.
WIND ENERGY • Generators are driven by windturbines (windmills). • Large, remote,windy sites are needed. Wind are variable. The wind turbines are noisy and can spoil the landscape.
WAVE ENERGY • Generators are driven by the up-and-down motion of waves at sea. • Difficult to built-few devices have been successful.
GEOTHERMAL ENERGY • ‘Geothermal’ means heat from the Earth. • Water is pumped down to hot rocks deep underground and rises as steam. • In areas of volcanic activity, the steam comes naturally from hot springs. • Deep drilling is difficult and expensive.
Solar Energy • Solar panels absorb this energy and use it to heat water. • Solar cells are made from materials that can deliver an electric current when they absorb the energy in light. • Variable amounts of sunshine in some countries. Solar cells are expensive, and must be large to deliver useful amounts of power. A cell area of around 10m is needed to power an electric kettle.
BIOFUELS • These are fuels made from plant or animal matter, sometimes called biomass. • They include wood, alcohol made from sugar cane,and methane gas from rotting waste. • Huge areas of land are needed to grow plants.
SAVING ENERGY • Burning fossil fuels causes pollution. • But the alternatives have their own environmental problems. • That is why many people think that we should be less wastefull with energy.
Methods could include using public transport and bicycles instead of cars, manufacturing goods that last longer, and recycling more waste materials. • Also, better insulation in buildings would mean less need for heating in cold countries and for air conditioning in hot ones.
