1. Unit D Section 4.0 The use of electrical energy affects society and the environment

2. 4.1 – Electricity Sources and Alternatives About 65% of the world’s energy comes from fossil fuels Fossil fuels are formed from dead plants and animals; coal, oil, and natural gas

3. Producing Electricity from Heat Fossil fuel power and nuclear power both produce heat that is used to make steam This high-pressure steam then turns a turbine The turbine then turns a generator, which produces electrical energy

4. A Coal-Fired Power Plant

5. Nuclear Fission Nuclear Fission: is the splitting of atoms, which transforms them into lighter elements and releases large amounts of energy

7. Other Sources of Heat Energy Geothermal energy is energy produced by the Earth itself Geysers, hot springs and thermal vents are all sources of geothermal energy

9. Cogeneration Cogeneration: use of waste energy from a process for another purpose, such as heating or generating electricity

10. Hydroelectricity 20% of the world’s electricity comes from hydroelectricity The force of falling water turns turbines, which in turn operate the generators

11. Renewable vs Non-Renewable Energy Renewable Energy: resource such as water or wind energy that is continually replenished and therefore can be used indefinitely Non-Renewable Energy: a resource, such as coal or natural gas, that cannot be replenished

12. Alternative Energy Sources Tides Wind

13. Sunlight Fuel Cells

14. 4.2 Electricity and the Environment Fly Ash: fine airborne ash produced by burning coal or other solid fuels fly ash contains small amounts of mercury, a poisonous metal that can damage the nervous system.

15. Sustainability If energy is conserved, then less energy is required This puts less of a strain on energy sources As well, a greater demand for fuels and energy drives up prices Therefore, conservation not only reduces environmental impacts, but it also reduces energy demands and the price of energy

16. Sustainability Ultimately, we should hope achieve sustainable energy use (use of resources at a rate that can be maintained indefinitely without depleting the resources or harming the environment) This may involve making compromises regarding how we use energy in the future

17. 4.3 – Electrical Technology and Society Electrical communication originated in 1844 when Samuel Morse sent the first telegraph message Since then, electrical technologies have continually developed and evolved to meet the needs of our society

18. Benefits of Electrical Technologies Speed and convenience

19. Drawbacks of Electrical Technologies Makes sustainability difficult Increase in solid waste materials Expensive for developing countries to adopt

20. Computers and Information Computers have changed since the unveiling of ENIAC in 1946 Now, modern computer chips 0.5 mm square have the same computing power as the room-sized ENIAC

21. Computers use Binary numbers (zeroes and ones) that correspond with the on and off states of the millions of tiny transistors in microcircuits

22. Electricity and Computers Computers use several ways to store information CDs and DVDs have tiny pits on their surface When a laser runs over the pits, it produces a digital signal which the computer then decodes

23. Hard drives use pulses of electricity to encode information onto a magnetic disk which rotates at speed up to 300 km/h The magnetized sections of the disc are read by the computer, which produces a digital signal which is decoded by the computer

25. Electrical Transmission of Information Digital data can easily be transmitted and shared due to advances in technology such as wireless technology and the internet However, these developments have a number of major drawbacks:

26. Privacy and Security Identity Theft: Private Information:

27. Validity of Information Information Sources: Propaganda:

28. Information Overload Searching for Information: