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Fossil fuels were formed in the ground from the remains of living organisms from millions of years ago and are now burned to produced heat energy, making up for most of the electricity generated in the world. Some examples of fossil fuels are coal, natural gas and oil. They are very widely used for their high power output, cheap price and how easily they can be obtained. However, fossil fuels are non-renewable, meaning that at some point in the future they will run out. They also produce carbon dioxide, which contributes to global warming and the greenhouse effect, and sulfur dioxide, which can cause difficulties in breathing and contribute to acid rain, while burning.
Nuclear fuels are used to release energy through nuclear reactions, which is used to boil water and the steam produced to spin turbines which generate electricity. The main types of nuclear fuels are uranium and platonium. Nuclear fuels are reliable, have a high power output and produces no greenhouse or harmful gases. However, nuclear fuels are a non-renewable source of energy and they also produce radioactive decay which will take thousands of years to decay.
One renewable source of energy is biofuels. Biofuels are burned as raw materials to produce heat which is used to run turbines to generate electricity. Biofuels are fuels made from plant materials, which is what makes them renewable, as well as reliable, as they can be grown anywhere. Two examples of biofuels are bioethanol, which is fermented sugar and wheat, and biodiesel, which is made from plant oils. Using biofuels is a sustainable substitute for fossil fuels, as they produce less carbon emissions, since the plant approximately takes in as much carbon during its life as it releases when it is burned. However, growing biofuels takes up land space and resources that could have been used to grow food and does not produce a high power output, and thus can only be used on a small scale.
The energy from the sun drives wind currents. The kinetic energy of this wind is a renewable source of energy and can be used to generate electricity using turbines. Turbines have blades attached to a big tower, which spin due to the wind. These blades are connected to a nacelle in the centre, which holds gears that are linked to a generator. Thus when the blades spin, the generator also spins and electricity is produced. Wind energy is a very sustainable source of energy, as it is renewable and produces no harmful gases. However, the wind is not a reliable source of energy, since it depends on the strength of it and whether or not there is wind. Also, wind turbines can become noisy and spoil the land and views that they are placed on.
There are three ways in which water energy can be used to generate electricity. The first way is usnig waves: waves move the surface of the water up and down, and wave machines use the kinetic energy from this movement to drive electricity generators. The second way is using tides, which works just as waves; tides cause water to rush through a tidal barrage which contains a generator, and thus producing electricity. The third way is hydroelectric power, which uses water coming from behind a dam that has high gravitational potential energy. Tubes are set up inside the dam, in which the water's gravitational potential energy is transferred to kinetic energy when the water goes through the tubes. This water drives generators inside the dam, thus producing electricity. Water energy is a renewable and reliable source of energy, which produces no hamrful gases. However, machinery that will produce great amounts of electricity is difficult to design. Animal habitats are also destroyed when dams and machinery are set up and these may also cause flooding, which will drive people away from these areas. Underwater vegetation in dams also rots, causing methane to be released, which is a greenhouse gas.
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