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Alternate Energy

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  1. Alternate Energy Energy Efficiency and Renewable Energy

  2. Key Concepts • Energy efficiency • Solar energy • Types and uses of flowing water • Wind energy • Biomass • Geothermal energy • Use of hydrogen as a fuel • Decentralized power systems

  3. The Importance of Improving Energy Efficiency • Energy efficiency • Net energy efficiency Least Efficient • Incandescent lights • Nuclear power plants • Internal combustion engine

  4. Energy Efficiencies

  5. Ways to Improve Energy Efficiency • Cogeneration • Efficient electric motors • High-efficiency lighting • Increasing fuel economy • Alternative vehicles • Insulation • Plug leaks

  6. Hybrid and Fuel Cell Cars • Hybrid electric-internal combustion engine • Fuel cells

  7. 1 2 Hydrogen gas 3 4 H2 Cell splits H2 into protons and electrons. Protons flow across catalyst membrane. 3 1 O2 React with oxygen (O2). 2 Produce electrical energy (flow of electrons) to power car. 4 H2O Emits water (H2O) vapor.

  8. Hybrid Car A C Electric motor Traction drive provides additional power, recovers breaking energy to recharge battery. Combustion engine Small, efficient internalcombustion engine powers vehicle with low emissions. D B Fuel tank Liquid fuel such as gasoline, diesel, or ethanol runs small combustion engine. Battery bank High-density batteries power electric Motor for increased power. E Regulator Controls flow of power between electric Motor and battery pack. F Transmission Efficient 5-speed automatic transmission. B A E F C D Fuel Electricity

  9. Fuel Cell Car Fuel cell stack Hydrogen and oxygen combine chemically to produce electricity. Fuel tank Hydrogen gas or liquid or solid metal hydride stored on board or made from gasoline or methanol. A C D B Turbo compressor Sends pressurized air to fuel cell. E Traction inverter Module converts DC electricity from fuel cell to AC for use in electric motors. Electric motor/transaxle Converts electrical energy to mechanical energy to turn wheels. B A E C D Fuel Electricity

  10. Universal docking connection Connects the chassis with the Drive-by-wire system in the body Body attachments Mechanical locks that secure the body to the chassis Rear crush zone absorbs crash energy Air system management Fuel-cell stack Converts hydrogen fuel into electricity Drive-by-wire system controls Cabin heating unit Side mounted radiators Release heat generated by the fuel cell, vehicle electronics, and wheel motors Front crush zone Absorbs crash energy Hydrogen fuel tanks Electric wheel motors Provide four-wheel drive Have built-in brakes

  11. 1.4 1.2 Energy useper capita 1.0 Index of energy use per capita andper dollar of GDP (Index: 1970=1) 0.8 0.6 0.4 Energy useper dollar of GDP 0.2 0 1970 1980 1990 2000 2010 2020 Year

  12. 30 25 Cars Average fuel economy (miles per gallon, or mpg) 20 Both 15 Pickups, vans, and sport utility vehicles 10 1985 1970 1975 1980 2005 2000 1990 1995 Model Year

  13. 2.2 2.0 1.8 1.6 Dollars per gallon (in 1993 dollars) 1.4 1.2 1.0 0.8 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year

  14. Using Solar Energy to Provide Heat • Passive solar heating • Active solar heating

  15. Net Energy Efficiency Super insulated house(100% of heat R-43) 98% Geothermal heat pumps (100% of heating and cooling)) 96% Passive solar (100% of heat) 90% Passive solar (50% of heat) plus high- efficiency natural gas furnace(50% of heat) 87% Natural gas with high-efficiency furnace 84% Electric resistance heating (electricity from hydroelectric power plant) 82% Natural gas with typical furnace 70% Passive solar (50% of heat) plus high-efficiency wood stove (50% of heat) 65% Oil furnace 53% Electric heat pump (electricity from coal-fired power plant) 50% High-efficiency wood stove 39% Active solar 35% Electric heat pump (electricity from nuclear plant) 30% Typical wood stove 26% Electric resistance heating (electricity from coal-fired power plant) 25% Electric resistance heating (electricity from nuclear plant) 14%

  16. 1 ft2 of collector = 1 gallon of hot water 1 person uses about 20 gallons/day

  17. Active and Passive Solar House in Belmont NY (upstate west of Alfred NY)

  18. Passive Thermal Mass House

  19. Passive Solar Heater

  20. Summer sun Heavy insulation Super window Winter sun Super window Stone floor and wall for heat storage PASSIVE

  21. Heat to house (radiators or forced air duct) Pump Heavy insulation Hot water tank Super- window Heat exchanger ACTIVE

  22. R-60 or higher insulation R-30 to R-43 insulation Small or no north-facing windows or super windows Insulated glass, triple-paned or super windows (passive solar gain) R-30 to R-43 insulation House nearly airtight R-30 to R-43 insulation Air-to-air heat exchanger

  23. Direct Gain Ceiling and north wall heavily insulated Summer sun Hot air Super insulated windows Winter sun Warm air Cool air Earth tubes

  24. Greenhouse, Sunspace, or Attached Solarium Summer cooling vent Warm air Insulated windows Cool air

  25. Earth Sheltered Reinforced concrete, carefully waterproofed walls and roof Earth Triple-paned or super windows Flagstone floor for heat storage

  26. Using Solar Energy to Provide High-Temperature Heat and Electricity • Solar thermal systems • Photovoltaic (PV) cells

  27. Solar Energy Calculation • We live at about 40o N and receive about 600 W /m2 • So over this 8 hour day one receives: • 8 hr x 600 W /m2 = 4800 W-hr /m2 = 4.8 kW-hr / m2 • 4.8 kW-hr / m2 is equivalent to 0.13 gal of gasoline • For 1000 ft2 of horizontal area (typical roof area) this is equivalent to 12 gallons of gas or about 450 kW-h

  28. Photovoltaic Array

  29. Single Solar Cell Boron-enriched silicon Sunlight Junction Cell Phosphorus- enriched silicon DC electricity

  30. Roof Options Panels of Solar Cells Solar Cells

  31. Solar Cell Roof

  32. Trade-Offs Solar Energy for High-Temperature Heat and Electricity Advantages Disadvantages Moderate net energy Moderate environmental Impact No CO2 emissions Fast construction (1-2 years) Costs reduced with natural gas turbine backup Low efficiency High costs Needs backup or storage system Need access to sun most of the time High land use May disturb desert areas

  33. Solar Steam Generator Barstow, California

  34. Producing Electricity from Moving Water • Large-scale hydropower • Small-scale hydropower • Pumped-storage hydropower • Tidal power plant • Wave power plant

  35. Trade-Offs Large-Scale Hydropower Advantages Disadvantages Moderate to high net energy High efficiency (80%) Large untapped potential Low-cost electricity Long life span No CO2 emissions during operation May provide flood control below dam Provides water for year-round irrigation of crop land Reservoir is useful for fishing and recreation High construction costs High environmental impact from flooding land to form a reservoir High CO2 emissions from biomass decay in shallow tropical reservoirs Floods natural areas behind dam Converts land habitat to lake habitat Danger of collapse Uproots people Decreases fish harvest below dam Decreases flow of natural fertilizer (silt) to land below dam

  36. Producing Electricity from Wind

  37. Gearbox Electrical generator Power cable Wind Turbine

  38. Basics of Wind Energy • Velocity measured in meters per second (m/s) • Power is measured in Kilowatts (kW) • 1 m/s is a little more than 2 mile/hr (mph)

  39. Basics of Wind Energy • Kinetic Energy (of wind) is: 1/2 * mass * velocity2 • KE = 1/2 mv2 • The amount of air moving past a given point (e.g. the wind turbine) per unit time depends on the wind velocity. • Power per unit area = KE* velocity or P= mv2*v = mv3 • So Power that can be extracted from the wind goes as velocity cubed (v3)

  40. Basics of Wind Energy • Power going as v3 is a big deal. • 27 times more power is in a wind blowing at • 60 mph than one blowing at 20 mph. • For average atmospheric conditions of density • and moisture content: Power /m2 = 0.0006 v3

  41. Sample Wind Problem • How much energy is there in a 20 mph wind? • 20 mph wind =10 m/s • Power = 0.0006 * v 3 • Power = 0.0006 * (10) 3 • Power = 0.0006 * 1000 = 0.6 kW/m2 • Which is equal to 600 W/m2 • This is identical to average solar power per square meter at our latitude.

  42. Sample Wind Problem • Example calculation: • Windmill efficiency = 42% • Average wind speed = 10 m/s (20 mph) • Power * efficiency = 0.0006 x 1000 x 0.42 = 250 W/m2 • 250 W/m2 / 1000 W/kW = 0.25 kW/m2 • Electricity generated is then 0.25 kW-h/m2 • If wind blows 24 hours per day then annual electricity generated would be about 2200 kW-h/m2 • (0.25 kW-h/m2 x 24h/d x 365d/yr = 2190kW-h/m2 )