How can we get rid of garbage? How can we get rid of garbage (垃圾)? Do we have enough energy sources to meet our future energy needs? These are two important questions that many people are asking today. Some people think that we might be able to solve both problems at the same time. They suggest using garbage as an energy source. For a long time people have buried garbage or dumped (倾倒) it on empty land. Now while empty land is getting scarce, more and more garbage is being produced each year. Fortunately, garbage can be a good fuel to use. The things in garbage do not look like coal, petroleum, or natural gas; but they are chemically similar to these fossil fuels. As we use up our fossil-fuel supplies, we might be able to use garbage as an energy source. Burning garbage is not a new idea. Some cities in Europe and America have been burning garbage for years. The heat that is produced by burning garbage is used to boil water. The steam that is produced is used to make electricity or to heat nearby buildings. In Paris, France, some power plants burn almost 2 million tons of the city's garbage each year. The amount of energy produced is the same as would be produced by burning almost a half million barrels (桶) of oil! But there are problems m using garbage as a fuel. Some garbage-that burns easily, like food scraps and paper, must be separated from metals, glass, and other materials that do not burn easily. This separation process is normally costly. Another problem is that burning garbage can pollute the air. Our fossil fuel supplies are limited. Burning garbage might be one kind of energy source that we can use to help meet our energy needs. This method could also reduce the amount of garbage piling up on the earth.