The whole world needs energy . Without it people could not cook their food, heat their homes, or run their machines. All of the countries today depend heavily on petroleum, coal, and natural gas provided electricity and supply fuel for heat. Natural gas is also used for cooking. Cars, trucks, and machines run on petroleum .
Coal first became an important fuel in the 1800s. Natural gas and petroleum became important during the 1900s. None was expensive then. People could easily afford them. It seemed that the fuels were also plentiful. Most people didn't worry about the possibility of using them up. They also rarely though to ask whether the energy was clean or safe. Much of it wasn't.
When petroleum and coal are burned, they put harmful gases and soot into the air. Nuclear power , which began to be used in the late 1950s, can also damage the environment. Nuclear fuels give off invisible radiation that is poisonous to people, animals, plants, air and water. Some wastes from nuclear fuel continue to give off radiation for thousands of years. These wastes must be kept perfectly sealed for all that time. Otherwise, poisonous radiation could leak out. There is still o absolute safe way to do this.
By the 1970s, people had begun to see that there was an energy problem . They recognized great hazards to health and safety. They also saw that the earth's supplies of petroleum, coal, and natural gas couldn't last forever. They began looking for new energy sources, and for safe and clean ways to use them. The wind is one safe and unlimited source of energy. Moving air can turn the blades of windmills. Windmills have been used for centuries to pump water and grind grain. Some newer windmills can make great amounts of electricity . Falling water is another energy source. Like wind, it can make blades spin. That movement can be turned into electricity. Electricity created by falling water is called hydroelectric power .
There are also some energy sources that might surprise you. One is the movement of ocean tides . Another is the steam or hot water trapped under the earth's surface. Even common garbage can be converted into fuel. Direct use of the sun's rays is one new way to heat homes and buildings. A solar collector is put on the roof. The heat it collects can be used right away of safely stored for future use. With the help of small device called a photovoltaic cell , the sun's rays can also produce electricity. When sunlight falls on a photovoltaic cell, the result is electricity. This process is already being used to make electricity in small parts of the world.
So far, solar energy has been used only to a limited extent. But researchers are developing it more extensively now. It is necessary to find cheaper energy sources. As coal, natural gas, and petroleum become scarcer, their prices go up. But the cost of solar energy is coming down every year. People are interested in learning how to make greater use of solar power, of wind and falling water, of tides and underground steam. These newer energy sources are clean and safe. And they can never be used up.
note: originally posted at Exposeknowledge.com under the same author.
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