Chapter 6: Electric Energy at Home Unit B: Energy Transformations
6.1 Generating Electric Energy • A generator is a device that makes electricity. • Michael Faraday made the first electric generator in the early 1800s. • Pushing a magnet through a coil of wire generates an electric current, more coils and stronger magnets produce more electric energy. • The large amounts of electricity that we use today are produced by gigantic generators. Input Energy Converter Output Energy Kinetic Energy Generator Electric Energy
6.2 Generating and Distributing Electric Energy • Most electricity is made in a generator. Generators contain one or more turbines. • As the blades of the turbines turn, their kinetic energy is transformed into kinetic energy in the generator. This is what produces energy. • See figure 6.5 on Pg 102 • Hydro-electric: converts kinetic energy of moving water into electric energy • Thermo-electric: converts chemical energy stored in fossil fuels into thermal energy, then to kinetic energy, then to electric energy • Thermonuclear: splits atoms, releasing thermal energy that is converted to kinetic energy, then to electric energy
6.2 Generating and Distributing Electric Energy (Continued) • Coal-fired thermo-electric plants burn coal to generate electric energy. The smoke from burning the coal is put through scrubbers to remove the harmful chemicals. • See Figure 6.8 on Pg 104 • What are the advantages and disadvantages of using fossil fuels like coal, petroleum, and natural gas?
6.2 Generating and Distributing Electric Energy (Continued) • Hydro-electric plants produce much of the electric energy in Canada. • Kinetic energy from falling water is used to generate electric energy • Clean, efficient/little maintenance, little environmental damage, and no emissions • Require large dams which change the ecology of the area
6.2 Generating and Distributing Electric Energy (Continued) • Thermonuclear generation stations split uranium atoms using nuclear fission. This releases a large amount of thermal energy. The energy is then used to make steam and the steam, under pressure, turns a turbine. • See Figure 6.9 on Pg 106 • What are the advantages and disadvantages of nuclear energy?
6.2 Generating and Distributing Electric Energy (Continued) • Thermonuclear and thermo-electric plants are sometimes located close to cities. This lessens the distance to transmit the power, but creates environmental issues. • Electricity must be transmitted through power lines to get to the communities they serve. About 10% of the electricity is converted to thermal energy and wasted. • Power lines can also cause problems because heavy storms may cause damage to the power lines and it could take weeks to repair.
6.3 Electric Energy and Power • Energy is the ability to do work. • Work is defined by force (F) multiplied by distance (d) over which the force is applied. • Work = F × d • The joule is the unit used in measuring work. • Force is measured in newtons. • When a newton of force is applied for one meter of distance (1 N × m), one joule of work is done. • Power is the rate at which energy is transferred. Power tells how fast energy is used or produced. • If a machine useds one watt of power, it uses one joule of energy in one second.
6.3 Electric Energy and Power (Continued) • The consumption of electric energy is measured in watts. The watts are multipled by the time it takes to use them. • Energy = power × time • 1 watt hour (W×h) = 1 watt × hour • The watt hour is a small unit of energy. Electiric utility companies use a unit of energy 1000 times larger. • One kilowatt hour is equal to 1000 watt hour • kW×h
6.4 Efficiency and Saving Energy • Incandescent light bulbs produce light when electricity flowing through the filament makes the thin wire white hot. • Efficiency is a measure of how completely input energy is converted to accomplish the desired output energy. • Incandescent light bulbs produce more heat than flourescent bulbs, so flourescent bulbs are more efficent. Percent efficiency of an electric device = useful energy output × 100 total electric enrgy input
6.4 Efficiency and Saving Energy (Continued) • Efficiency is important to you and the environment. • You: Use less electricity, save on your monthly utility bill. • Environment: Electricity is generated by fossil fuels. • As coal burns, it produces carbon dioxide, sulfur dioxide, and nitrous oxide gases. These are released into the atmosphere and harmful emissions. • Carbon dioxide is linked to global climate change. • Sulfur dioxide and nitrous oxides are the primary causes of acid deposition.