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Earth Science Chapter 5 - Summary Notes
á A natural resource can be renewable or nonrenewable. Renewable resources, like trees, replace themselves quickly. Nonrenewable resources, like coal, take thousands or million of years to replace.
á People use many resources faster than the earth replaces them. Recycling is a process that treats materials for reuse so that we donÕt have to gather as many resources from nature.
á All energy resources can be traced back to the sun. The energy resource we use the most are fossil fuels.
á Fossil fuels are nonrenewable. They form from the remains of dead organisms that are millions of years old.
á Petroleum, or crude oil, is the liquid fossil fuel we get gasoline from.
á Gaseous fossil fuels are natural gases. Natural gases power our kitchen stoves.
á Coal is a solid fossil fuel that comes from buried, decomposed plant material. Coal is also a rock.
á We are always looking for alternative energy sources because obtaining fossil fuels harms the environment. When coal is burned, sulfor dioxide is released and combines with the moisture in the air to make acid rain (sulfuric acid).
á Nuclear energy is an alternative source of energy that comes from splitting the nuclei of atoms. This process is called fission, and it releases a lot of energy that is used to run electric generators in power plants. The waste products are easy to contain, but it is hard to know where to bury them.
á Solar cells, like the ones on calculators, get their energy directly from the sun. Solar energy does not pollute like many other energy resources, but solar panels are very expensive to make.
á Wind is another clean energy source. However, wind turbines are only effective in places where the wind is steady, such as California and north Texas.
á Hydroelectric energy uses the power of falling water to make energy. Like wind energy, hydroelectric energy cannot be harnessed everywhere. Dams built to harness this energy also hurt the fish populations and other wildlife.
á Underground water is hot enough in some places to evaporate into steam. Geothermal energy uses the steam from natural vents called geysers to power electric generators.