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Energy Conversion

Energy Conversion. Ex: Flashlight: chemical PE (batteries) → light energy Engine: chemical PE (gasoline) → kinetic energy. Energy resources from the earth’s crust. Energy: Joule (J) Calorie (cal) = 4.2 J 1 cal raises 1 g of H 2 O by 1 o C

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Energy Conversion

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  1. Energy Conversion • Ex: • Flashlight: • chemical PE (batteries)→ light energy • Engine: • chemical PE (gasoline) → kinetic energy

  2. Energy resources from the earth’s crust

  3. Energy: Joule (J) Calorie (cal) = 4.2 J 1 cal raises 1 g of H2O by 1oC British thermal unit (Btu) ~ 250 cal ~ 1000 joules 1 kJ = 1000 J 1 MJ = 1000 kJ =1,000,000 J Power: Power = energy/ unit of time Watt (W) = 1 J/sec kW = 1000 W = 1000 J/sec. 1 MW = 1000 kW = 1,000,000 W Horsepower (HP) ~ 750 W Examples: Hair dryer ~ 1 kW Light bulb ~ 100 W wood ~ 7.5 MJ/lb. coal ~ 15 MJ/lb. oil ~ 150 MJ/gal natural gas ~ 1.4 MJ/cu.ft. 1 barrel (bbl) oil ~ 6 billion J 2 tons coal ~ 6 billion J 4 tons wood ~ 6 billion J 1 gal gasoline ~ 130 MJ U.S. per capita energy consumption ~ 57 bbl oil/year

  4. Oil & Gas • HC (hydrocarbons) • Energy is stored in chemical bonds • Combustion • breaks bonds, releases Energy + CO2 + H2O • Example: • methane (CH4) • CH4 + 2O2 energy + CO2 + 2H2O octane (C8H18)

  5. Power Plant Diagram Sources of Energy 1. Boiler creates steam 2. Steam turns turbine 3.Turbine powers generator

  6. Nuclear Energy • Fission begins a chain reaction • Huge amounts of energy released

  7. Three Mile Island • 1979 - Harrisburg, PA • partial meltdown of reactor • radioactive steam released • 50,000 people evacuated • no immediate deaths • possible increased cancer rates

  8. Chernobyl • 1986 reactor explosion • Ukraine officials - 3,576 deaths • Greenpeace - 32,000 deaths • 400,000 people evacuated • 62,000 sq. mi. contaminated

  9. How Nuke Waste is Handled: • stored in Fuel Pools at each plant

  10. Wind turns turbine • Turbine turns generator • Generator creates electricity

  11. Wind • Cape Cod, MA • proposed wind farm • 130 turbines • 420 MW X

  12. Summary - Wind • Competitive Cost • No pollution • NIMBY • “Not In My Back Yard” • Visual pollution

  13. 1. Geothermal Power Plants • electricity from natural steam • geysers (Old Faithful) and volcanoes (Iceland, Hawaii) • roughly 20 - 50 MW

  14. 3. Geothermal – heat pump • Ground is constant ~ 50 Fo year-round • cools in summer • warms in winter • uses a heat pump • heat from ground to house in winter • heat from house to ground in summer

  15. Solar Energy - Heating 1. Passive system: Absorbs & stores heat from the sun directly 2. Active system: Solar energy heats water used to heat building

  16. 3. Solar Energy - electric generation • Photovoltaic cells • No sun = no power • Example: 14 panels = 850 W

  17. Sources of Energy

  18. Tide Power • “underwater windmills” • prototype - East River, NYC

  19. Fuel Cells • Fuel is hydrogen & oxygen • 2H2 + O2 2H2O + energy • problems: • source of H2? • storage/distribution of H2

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