What is Renewable Energy?
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Renewable Energy What is Renewable Energy? Renewable energy means it comes from a source that's constantly renewed - the wind keeps blowing, the sun keeps shining, and the Earth keeps heating underground rocks. This energy will be around for as long as the Earth is, so we don't have to worry about running out of it. And renewable energy sources are also usually less pollutant. There are seven sources of renewable energy: * Solar Energy * Biomass * Wind Energy * Wave Energy * Hydro-electric Energy * Tidal Energy * Geothermal Energy Solar Energy Solar energy is energy taken from the sun's rays. The amount of energy that falls from the sun each day can reach the amount of energy used in total around the world per year. The sun's rays have a low energy density so large panels and collecting devices must be used to gather the energy and convert it into electricity. Solar heating Have you ever sat in a car that was closed up on a sunny day? Did you notice how hot it was in the car? This warmth is just one example of solar heating. We can use the sun to heat other things, including our homes. Today, more than 200,000 houses in the United States have been designed to use features that take advantage of the sun's energy. These homes often use passive solar designs, which do not normally require pumps, fans, or other mechanical equipment to store and distribute the sun's energy.
Hydro-electric Energy The water in rivers and streams can be captured and turned into hydropower, also called hydro-electric power. The most common form of hydropower uses dams on rivers to create large reservoirs of water. Water released from the reservoirs flows through turbines, causing them to spin. The turbines are connected to generators that produce electricity. Hydro-electric power plants in the United States generate enough electricity to power whole towns, cities, and even entire regions of the country. Hydropower currently is one of the largest sources of renewable power, generating about 10 percent of the United States' electricity. Hydropower is also inexpensive, and like many other renewable energy sources, it does not produce air pollution. However, the drawback to hydropower is that damming rivers can change the ecology of the region. For example, the water below the dam is often colder than what would normally flow down the river, so fish sometimes die. The water level of the river below the dam can be higher or lower than its natural state, which affects the plants that grow along the riverbanks. Tidal Energy There are a few places in the world where there is a large enough difference between the high and low tides of the ocean to generate electricity. The gravity of the moon pulls on the earth and causes our tides to rise and fall as it travels in its orbit.
Some of the tiny particles also get caught up in the swirling combustion gases and, along with water vapour, form the smoke that comes out of a coal plant's smokestack. Also coal, like all fossil fuels, is formed out of carbon. All living things - even people - are made up of carbon. But when coal burns, its carbon combines with oxygen in the air and forms carbon dioxide. Carbon dioxide is a colourless, odourless gas, but in the atmosphere, it is one of several gases that can trap the earth's heat. Sounds like coal is a dirty fuel to burn. Many years ago, it was. But things have changed. Especially in the last 20 years, scientists have developed ways to capture the pollutants trapped in coal before the impurities can escape into the atmosphere. Today, we have technology that can filter out 99 percent of the tiny particles and remove more than 95 percent of the acid rain pollutants in coal. Nuclear Nuclear power plants provide about 17 percent of the world's electricity. Some countries depend more on nuclear power for electricity than others. In France, for instance, about 75 percent of the electricity is generated from nuclear power. In the United States, nuclear power supplies about 15 percent of the electricity overall, but some states get more power from nuclear plants than others. There are more than 400 nuclear power plants around the world. Nuclear power stations, unlike coal, do not produce sulphur dioxide and carbon dioxide. However, radioactive waste is very dangerous for thousands of years and safe storage is expensive. By Chris Sampson
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