1. Warm - Up 1. What is the process called when atoms are split?
2. What is the difference in reactions between a nuclear bomb and a nuclear power plant?
3. What are some advantages of nuclear energy?
4. What are some disadvantages of nuclear energy?

2. Chapter 18
Renewable Energy

3. Renewable Energy
Renewable energy – energy from sources that are constantly being formed
Solar
Wind
Water
Earth’s heat

4. Solar Energy Sun - Medium sized star Nuclear fusion in the core
Fraction reaches the Earth
All renewable energy comes directly or indirectly from the Sun

5. Passive Solar Heating Sun’s energy directly heats
Passive solar buildings – which way are windows (Northern Hemisphere)?
Thick insulation

6. Passive Solar Heating Summer – sun in high in the sky
Overhang cools
Winter – sun low in the sky
Sunlight enters windows

9. Active Solar Heating Sun’s energy is captured in collectors
Roof mounted
Liquid heated in collectors
Heats water for home

12. Photovoltaic Cells Solar cells Convert sun’s energy into electricity
Nonpolluting
Small electrical current
Hundreds of acres of panels to heat a small town

14. Solar Cells
Extended periods of sunlight
Energy stored in batteries

15. Wind Power Fastest growing energy source Cost effective
Erected in 3 months

17. Wind Farms
Windiest spots on Earth – generate more than 10X energy used worldwide
Problem – transporting energy in rural areas to urban areas

20. Biomass Fuel
Plant material, manure, or an other organic material used for energy
Burning dung or wood
Wood is renewable to an extent

22. Methane Bacteria decomposes organic waste – methane
Bio-gas digesters: ferment manure
Dung-fired power station: produces electricity
Decomposition of trash

25. Alcohol and Ethanol Ethanol or alcohol
Fermented fruits or agricultural waste
Corn – U.S.
Gasohol – blend of gas and ethanol

26. Hydroelectricity Energy from moving water Expensive to build
Inexpensive to operate
Last longer than fossil fuel plants
Disadvantages?

27. Micro-hydropower
Small streams
No big dams
Cheaper
More remote areas

29. Geothermal Energy Energy from heat inside the Earth’s crust
Pumps water or steam into a turbine
U.S. in #1

31. Geothermal Heat Pump

32. Alternative Energy
Energy sources that are still in development

33. Tidal Power Tide rises – water flows behind dam
Tide lowers – water trapped behind dam
Released and turns turbine
Expensive

35. OTEC Ocean thermal energy conservation
Differences in water temperatures
Surface – warm
Deep – cold
Water boils at low temperatures in low pressure vacuum
Boiling water  stream  turbine

37. Hydrogen Gas When burnt combines with oxygen – H2O
Produced when electricity splits water

38. Hydrogen Gas
Expensive to produce
Pollution
Must be compressed

39. Fuel Cell Fuel cell - produces electricity chemically
Combines hydrogen fuel with oxygen from the air

40. Energy Efficiency
Energy efficiency (in %) = useful energy out//energy in x 100

41. Cogeneration
Production of two useful forms of energy from same fuel source
Waste heat from industrial furnace to turn turbine

42. Green Gadgets Video Clips