UNIT FIVE: Electricity and Magnetism  Chapter 16 Electricity  Chapter 17 Magnetism

Chapter Seventeen: Magnetism  17.1 Properties of Magnets  17.2 Electromagnets  17.3 Electric Motors and Generators  17.4 Generating Electricity

Chapter 17.4 Learning Goals  Review the meaning of mechanical power and liken it to electrical power.  Compare and contrast renewable and nonrenewable sources of electrical energy.  Discuss methods of electrical energy conservation.

17.4 Generating Electricity  Electricity is made in a power plant.  Most power plants burn fossil fuels (natural resources like coal, oil, or natural gas) to produce heat.

17.4 Generating Electricity  Next, this heat is used to boil water.  The steam from the boiling water turns a turbine.  The turbine turns a generator which produces electricity.

17.4 Electricity from fossil fuels  A nonrenewable resource is not replaced as it is used.  Because it takes so long for these resources to form, someday we will not have enough fossil fuels to produce the electricity we need.  The three major fossil fuels are coal, oil, and natural gas.

The United States gets about 19% of its electricity production from nuclear power plants.

17.4 Electricity from nuclear energy  The main advantage of using nuclear energy to produce electricity is that it doesn’t pollute the air like fossil fuel power plants do.

17.4 Electricity from nuclear energy  Storage of nuclear waste has always been a major disadvantage of nuclear power plants.  Uranium fuel from the reactor stays dangerously radioactive for a long time.

17.4 Electricity from renewable resources  A renewable resource can be replaced naturally in a relatively short period of time.  The Sun and wind are renewable resources that can be used as energy sources.

17.4 Electricity from renewable resources  It is also possible to use:  moving water (hydroelectric)  hot spots near Earth’s surface (geothermal)  fuels made from once-living things like wood or corn (called biomass) or  tides to produce electricity.

17.4 Hydroelectric power  A hydroelectric (or hydropower) plant uses energy from falling water to generate electricity.

17.4 Geothermal and biomass  Geothermal power plants use Earth’s internal heat energy, in the form of water or steam, to produce electricity.  A geothermal heat pump system takes advantage of the relatively constant temperature of Earth’s shallow ground.

17.4 Geothermal and biomass  Biomass is organic material from plants or animals.  In waste-to-energy plants, renewable solid waste is burned to produce electricity, which also creates some air pollution.

17.4 Wind and solar energy  California was the first U.S. state to build large wind farms.  Wind farms can disturb natural habitats, and can perhaps scar a large area of scenery.

17.4 Wind and solar energy  The Sun’s energy is often called solar energy.  A solar cell (also known as a photovoltaic cell) can convert solar energy to electricity.

17.4 Electrical power  Electrical power is measured in watts, just like mechanical power.  Electrical power is the rate at which electrical energy is changed into other forms of energy such as heat, sound, or light.

17.4 Electrical power  Utility companies charge customers for the number of kilowatt-hours (kWh) used each month.  A kilowatt-hour is a unit of energy.  The number of kilowatt-hours used equals the number of kilowatts multiplied by the number of hours the appliance was turned on.

17.4 Electrical power  There are many simple things you can do to use less electricity.  When added up, these simple things can mean many dollars of savings each month.

Under the Sea  Have you ever wondered what it would be like to take a “walk” on the seafloor? Engineer Jim Varnum gets to go “down under” regularly, because he is a pilot of an extremely complex robot called Jason II. This robot dives deep into the ocean and is used to take pictures and collect data from the seafloor.