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All over the world in the twenty-first century, people can get new energy in many ways.
Energy from the wind.People use the power of the wind．It is a clean source(来源) of energy, and there is lots of it. However, if the wind does not blow, there is no wind energy.
Energy from the water.When water moves from a high place to a lower place, it has the power to make electricity. Waterpower produces enough energy for 40, 000 people in a town. Waterpower gives energy without pollution. However, people have to build dams(大坝) to use this energy, and building dams is very expensive.
Energy from the earth. There is heat in the rocks under the earth. Scientists use the heat to make geothermal(地热的) energy. San Francisco gets half of the energy from geothermal power. This kind of energy is cheap, but it is only possible in a few places in the world.
Energy from the sun. Solar panels(太阳能电池板) on the roofs of houses and buildings can turn energy from the sun into electricity. These panels can create enough energy to heat the whole house during winter. Solar power is clean and plentiful(丰富的), but when the weather is bad, it can't produce power．
