1. Chapter 18 Renewable Energy

2. Section 18-1 Renewable Energy Today

3. Discussion Prompt List 3 reasons you think we have not completely switched over to renewable energy to meet our energy needs. List 3 reasons you think we have not completely switched over to renewable energy to meet our energy needs.

4. Renewable Energy Renewable energy: energy from sources that are constantly being formed Renewable energy: energy from sources that are constantly being formed Solar Solar Wind Wind Moving water Moving water Geothermal (Earth’s heat) Geothermal (Earth’s heat)

5. Solar Energy Sun: medium-sized star that radiates energy from nuclear fusion reactions in its core. Sun: medium-sized star that radiates energy from nuclear fusion reactions in its core. Only a small fraction of this energy reaches the Earth yet it is enough to power the wind, plant growth, and the water cycle. Only a small fraction of this energy reaches the Earth yet it is enough to power the wind, plant growth, and the water cycle. Already commonly used Already commonly used Water cycle Water cycle Photosynthesis Photosynthesis Wind Wind Sunshine warming a room Sunshine warming a room Solar cells Solar cells

6. Passive Solar Heating Passive solar heating: Use sun to heat something directly Passive solar heating: Use sun to heat something directly Example: Northern hemisphere homes Example: Northern hemisphere homes Large, south facing windows absorb heat in winter Large, south facing windows absorb heat in winter Overhangs block sunlight in the summer Overhangs block sunlight in the summer Helps save money on energy bills Helps save money on energy bills Insulation is important also Insulation is important also

7. Active Solar Heating Active Solar Heating: Sun’s energy is gathered by collectors to heat a building or water Active Solar Heating: Sun’s energy is gathered by collectors to heat a building or water A liquid is heated by the sun and flows through solar collectors A liquid is heated by the sun and flows through solar collectors Solar water heaters Solar water heaters Water heated on roof Water heated on roof Hot water used to heat water supply Hot water used to heat water supply

8. Active Solar Heating, cont. Photovoltaic cells: convert the sun’s energy into electricity Photovoltaic cells: convert the sun’s energy into electricity No moving parts, no pollution No moving parts, no pollution Need many cells to produce decent yields Need many cells to produce decent yields Great potential in developing countries which have lesser energy demands Great potential in developing countries which have lesser energy demands Store energy in batteries Store energy in batteries

9. Wind Power Air is heated unevenly by the sun, creating wind Air is heated unevenly by the sun, creating wind Wind power is the fastest growing source of energy Wind power is the fastest growing source of energy Quadrupled between 1985 and 2000 Quadrupled between 1985 and 2000 Cost effective to build wind turbines Cost effective to build wind turbines Cost of wind power has declined Cost of wind power has declined

10. Wind Farms See Figure 7 on p. 495 See Figure 7 on p. 495 280,000 homes in CA powered by wind 280,000 homes in CA powered by wind Take up little space Take up little space Farmers add windmills to farm Farmers add windmills to farm Sell power to cities Sell power to cities

11. Currently Underused Windiest areas on earth could generate 10 times the energy used worldwide. Windiest areas on earth could generate 10 times the energy used worldwide. Difficult to transport the energy Difficult to transport the energy Wind farms may make hydrogen from water in the future. Hydrogen could be used as fuel. Wind farms may make hydrogen from water in the future. Hydrogen could be used as fuel.

12. Biomass Biomass Fuel: Plant material, manure, other organic matter used as fuel Biomass Fuel: Plant material, manure, other organic matter used as fuel Different than fossil fuels which are nonrenewable Different than fossil fuels which are nonrenewable Ex: wood and dung Ex: wood and dung Half of wood cut down is used for heating and cooking (developing countries) Half of wood cut down is used for heating and cooking (developing countries) Challenges Challenges Trees – renewable, but must be managed Trees – renewable, but must be managed Burning wood or manure – air pollution Burning wood or manure – air pollution

13. Methane Methane (CH 4 ) is created when bacteria decompose organic wastes Methane (CH 4 ) is created when bacteria decompose organic wastes Can be burned for heat or electricity Can be burned for heat or electricity China – 6 million homes use methane for heating and cooking China – 6 million homes use methane for heating and cooking England – Methane from cow manure as fuel for electricity England – Methane from cow manure as fuel for electricity USA – electricity from methane generated by landfills USA – electricity from methane generated by landfills

14. Alcohol Ethanol: made by fermenting fruit or agricultural waste Ethanol: made by fermenting fruit or agricultural waste Corn is a major source in the US Corn is a major source in the US Gasohol Gasohol mix of gasoline and ethanol mix of gasoline and ethanol Produces less pollution when burned Produces less pollution when burned Some states require (including GA) Some states require (including GA)

15. Hydroelectricity Hydroelectricity: Energy produced from moving water Hydroelectricity: Energy produced from moving water 20% of world’s electricity 20% of world’s electricity How it works (see p. 497) How it works (see p. 497) Reservoir behind a dam holds water Reservoir behind a dam holds water Flowing water turns turbines Flowing water turns turbines Turbines’ energy transferred to generator Turbines’ energy transferred to generator Generator turns movement into electricity Generator turns movement into electricity

16. Benefits of Hydroelectricity Expensive to build but cheap to operate Expensive to build but cheap to operate No air pollution No air pollution Last longer Last longer Flood control Flood control Water for drinking, agriculture, industry, and recreation Water for drinking, agriculture, industry, and recreation

17. Disadvantages of Hydroelectricity Disrupts river flow Disrupts river flow Ecosystems flooded behind dam Ecosystems flooded behind dam River flow diminished below dam River flow diminished below dam Displaces people Displaces people Farmland downstream less productive Farmland downstream less productive Decay in reservoir releases greenhouse gases Decay in reservoir releases greenhouse gases

18. Modern Hydroelectricity No new dams in the USA No new dams in the USA Brazil, India, and China still building large dams (developing countries) Brazil, India, and China still building large dams (developing countries) Micro-hydropower: small streams are used to move turbines without building dams Micro-hydropower: small streams are used to move turbines without building dams Cheaper Cheaper Can provide energy to remote areas Can provide energy to remote areas

19. Geothermal Energy Geothermal Energy: Energy from the heat in Earth’s crust Geothermal Energy: Energy from the heat in Earth’s crust How it works (see p. 498) How it works (see p. 498) Steam rises to turn turbines through a well Steam rises to turn turbines through a well Steam drives turbines, generating electricity Steam drives turbines, generating electricity Leftover liquid water pumped back into hot rock Leftover liquid water pumped back into hot rock The Geysers in CA powers 1.7 million homes (US uses more than any country) The Geysers in CA powers 1.7 million homes (US uses more than any country) Philippines, Iceland, New Zealand, Japan, Mexico, and Italy Philippines, Iceland, New Zealand, Japan, Mexico, and Italy Renewable, but must be managed Renewable, but must be managed

20. Geothermal Heat Pumps See Figure 12 on p. 499 See Figure 12 on p. 499 Temperature underground is constant Temperature underground is constant Pumps use stable underground temperatures to warm and cool homes Pumps use stable underground temperatures to warm and cool homes Loop of fluid in a pipe underground and into house Loop of fluid in a pipe underground and into house In summer, the fluid in the loop is cooler, so it cools the home In summer, the fluid in the loop is cooler, so it cools the home In winter, the fluid in the loop is warmer, so it warms the home In winter, the fluid in the loop is warmer, so it warms the home

21. Section 18-2: Alternative Energy and Conservation Discussion Prompt: Contrast alternative energy, renewable energy, and nonrenewable energy. Discussion Prompt: Contrast alternative energy, renewable energy, and nonrenewable energy.

22. Alternative energy Alternative Energy: Still in development Alternative Energy: Still in development Some renewable energy was once alternative energy (Ex: geothermal). Some renewable energy was once alternative energy (Ex: geothermal). Government investments are vital to development. Government investments are vital to development. Need to research Need to research

23. Tidal Power Tides are the movement of water caused by the gravitational attraction between the Earth, sun, and moon Tides are the movement of water caused by the gravitational attraction between the Earth, sun, and moon Currently used in France, Russia, and China Currently used in France, Russia, and China Benefits Benefits Tides happen 2 times a day Tides happen 2 times a day Generates electricity like hydroelectric dams Generates electricity like hydroelectric dams Drawbacks Drawbacks Expensive Few suitable locations

24. Ocean Thermal Energy Conversion (OTEC) Energy is created from the difference in temp. of the surface of ocean water and deep ocean water Energy is created from the difference in temp. of the surface of ocean water and deep ocean water Benefits Benefits Cold water boils at low temp in vacuum chamber Cold water boils at low temp in vacuum chamber Steam can turn a turbine Steam can turn a turbine Drawbacks Drawbacks Not cost effective Uses 1/3 of the energy it produces to pump the cold water up to the surface to be boiled Environmental effects unknown

25. Hydrogen Can be burned as fuel Can be burned as fuel Benefits Benefits The most abundant element in the universe The most abundant element in the universe No air pollutants when burned No air pollutants when burned Obtain by running electricity through water or from plants (more cost effective) Obtain by running electricity through water or from plants (more cost effective) Drawbacks Drawbacks Generating it uses energy, money, and makes pollution Takes a lot of hydrogen to create as much energy as gasoline so it must be compressed dangerous Explosive and dangerous

26. Fuel Cells See Figure 16 on p. 502 See Figure 16 on p. 502 Produce electricity chemically Produce electricity chemically Combine H 2 and O 2 and electricity is produced. Combine H 2 and O 2 and electricity is produced. Water is only byproduct Water is only byproduct Space shuttles use Space shuttles use

27. Energy Efficiency Energy Efficiency: percentage of energy put into a system that does useful work Energy Efficiency: percentage of energy put into a system that does useful work What you get out vs. what you put in What you get out vs. what you put in %Energy efficiency = %Energy efficiency = Read p. 502 to 503 and summarize energy efficiency today Read p. 502 to 503 and summarize energy efficiency today Useful energy out Energy in x 100

28. Efficient Transportation Read p. 503. Read p. 503. Describe how transportation could be made more efficient. Describe how transportation could be made more efficient.

29. Cogeneration Production of 2 useful forms of energy from 1 fuel source Production of 2 useful forms of energy from 1 fuel source Example: use waste heat from a furnace to turn a turbine Example: use waste heat from a furnace to turn a turbine

30. Energy Conservation Energy Conservation: saving energy Energy Conservation: saving energy Use energy efficient devices Use energy efficient devices Wasting less energy Wasting less energy Read about on p. 504 and 505 Read about on p. 504 and 505

31. Cities and Towns Osage, IA Osage, IA 3,600 people saved $1 million/year 3,600 people saved $1 million/year Sealed doors and windows Sealed doors and windows New efficient furnaces New efficient furnaces Insulated water heaters Insulated water heaters Businesses moved to the area Businesses moved to the area Unemployment is down Unemployment is down

32. Around the Home Spend $1,500/year on energy costs Spend $1,500/year on energy costs Much is wasted Much is wasted Insulation Insulation Efficient windows Efficient windows Weather stripping Weather stripping Wash clothes in cold water Wash clothes in cold water