Chapter 15 Section 3 What are our main energy sources? Objective: Name and describe the main sources of energy.

Key Terms hydroelectric power: electrical energy produced from moving water nuclear energy: energy produced by splitting or combining atoms

Fossil Fuels Fossil Fuels are the world’s main energy source. Oil, coal, and natural gas are fossil fuels. Fossil fuels can generate electricity and heat. They can also run car engines and other types of machinery.

Fossil Fuels However, most of our current energy sources have problems associated with them. Fossil fuels are rapidly being used up. Their use can also harm the environment.

Fossil Fuels People need to find ways to cut down on the use of fossil fuels. Some ways to do this include using energy-efficient cars, carpooling, lowering the heat, and turning off unneeded lights.

What are three fossil fuels? NAME: What are three fossil fuels? Answer: Three fossil fuels are oil, coal and natural gas.

Hydroelectric Power Water stored behind a dam has potential energy. When the water flows downhill, its stored potential energy changes to the energy of motion, which is called kinetic energy. The electrical energy power plants produce from running water is call hydroelectric power. At hydroelectric power plants, the moving water turns the blades of a machine that is called a turbine. The turbine drives an electric generator that produces electricity.

Hydroelectric Power Today, falling water is used to produce about 20 percent of the world’s electricity. Hydroelectric power does not pollute the air. Also, its energy source, moving water, is renewable. However, dams can affect the wildlife living on or near a river by changing the environment. Dams can also alter the natural flow of rivers.

What are two advantages of hydroelectric power plants? 2. DESCRIBE: What are two advantages of hydroelectric power plants? Answer: Two advantages of hydroelectric power plants are that hydroelectric power does not pollute the air and its energy source, moving water, is renewable.

Nuclear Power Energy produced by splitting atoms is nuclear power. The heat given off when atoms split can be used to produce steam. The steam powers generators to make electricity. Uranium is commonly used as fuel.

Nuclear Power There are drawbacks to using nuclear energy. Deadly radiation is produced in nuclear reactors. An accident could release this radiation. Also, a way must be found to safely store the wastes, which remain deadly for thousands of years.

Nuclear Energy Energy can also be released by combining atoms. However, this kind of nuclear energy is very difficult and costly to produce.

3. IDENTIFY: What are some problems with using nuclear energy? Answer: Some problems with using nuclear energy it produces deadly radiation, an accident could release this radiation, and a way must be found to safely store the wastes.

Classwork CHECKING CONCEPTS What is the most commonly used fossil fuel? How can you produce electricity from moving water? What kind of energy does a dam store? How is nuclear energy produced commercially? The most commonly used fossil fuel is oil. Moving water produces electricity by turning the blades of a machine that is called a turbine. The turbine drives an electric generator that produces electricity. A dam stores potential energy. Nuclear energy is produced commercially by using the heat from splitting atoms to produce steam which powers generators to make electricity.

Classwork THINKING CRITICALLY 5. HYPOTHESIZE: How might building a dam affect the living things in an area? Give an example. Possible Answer: Building a dam might affect the living things in an area by cutting off the water supply to animals and plant in the area. This may cause animals and plants to die off.

Classwork THINKING CRITICALLY 6. CLASSIFY: Classify each of the following items as having potential or kinetic energy: a. a book on a shelf b. milk in a bottle c. a book falling to the floor d. a parked car e. juice being poured f. a moving car potential energy potential energy kinetic energy potential energy kinetic energy kinetic energy