solar energy
All people may know that the sun is the fundamental energy source for the Earth. It can produce enormous power, called solar energy. This energy is a necessary condition for life because ˇ§[a]ll life on earth depends on energy from the sun. ... ˇ¨(ˇ§Solar energyˇ¨, n. ... Because it can be obtained directly and furnishes adequate energy to people, it has attracted lots of attention during the 20th century (ˇ§Solar energyˇ¨, n. ... Therefore, solar energy, which is now more widely used, can provide a lot of positive effects. There are many factors that cause people to utilize solar energy. ... Generally, people can not live without water, heat and electricity, which come from many kinds of energy sources, such as coal, fuel, gas and so on, so it is inevitable to consume them. Due to the fact that the global population is growing constantly, the demand of energy is greater. ... However, most natural resources are limited on earth, so people may face a big energy crisis. ... As a result, people have started to use solar energy as supplement. Another reason is that some energy sources influence the environment.