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| What do you use the Internet
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| Asked by:
Anonymous on Feb-09-2008 14:26:01 | |
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| Answer
1 Contributor: Anonymous on Feb-10-2008 10:38:37 |
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| solar energy is what makes life on Earth possible! Without the sun's energy to warm our planet, this planet would be much much colder. Of course, the sun's energy is also put to work in a variety of other ways too. For instance, plants use sunlight to grow with photosynthesis (note that fossil fuels, such as coal and oil, are really formed from solar energy because these fuels came from plants which used sunlight to grow millions of years ago!). Solar energy can also be used to heat things (just think of a car on a hot sunny day with the windows closed). Often sunlight is focused down using mirrors or lenses and this focused energy can be used to heat things to extremely high temperatures (thousands of degrees!). This heat can be used for a variety of things, such as turning water to steam and turning a turbine to make electricity, and even to cause chemical reactions to happen that require high temperature. Using solar energy to heat something very hot and using that heat to make electricity is called "solar thermal" electricity, and is in fact the most common way to make electricity from sunlight.
On the other hand, when most people think of solar power, they think of solar panels. Technically, these systems are knowns as photovoltaics. These panels, that you can sometimes see on people's roofs (and are often used to power emergency telephone boxes along side of highways in the US) don't use the sun's heat as energy. Rather, the panel absorbs the sunlight and makes electricity from it. This is also the same type of solar panels that are commonly used on satellites in outer space to power them. The conversion of sunlight to electricity can be an extremely efficient process in fact. The main limitation to photovoltaics today is their relatively high cost (compared for instance to burning coal to make electricity). However, with the threat of global warming from carbon dioxide emissions, you may see more and more solar energy being used! |  Report
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