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  Internal combustion engine  Nuclear power plants

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 3 4 1 2 3 4 H2H2 O2O2 H2OH2O Hydrogen gas Emits water (H 2 O) vapor. Produce electrical energy (flow of electrons) to power car. React with oxygen (O 2 ). Cell splits H 2 into protons and electrons. Protons flow across catalyst membrane.

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

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

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

11. Year 19701980199020002010 0 0.2 0.4 0.6 0.8 1.0 1.2 Index of energy use per capita and per dollar of GDP (Index: 1970=1) 2020 1.4 Energy use per dollar of GDP Energy use per capita

12. 30 25 20 15 10 197019751980 1990 2000 2005 Model Year Average fuel economy (miles per gallon, or mpg) Cars Both Pickups, vans, and sport utility vehicles 1985 1995

13. Year 1920193019401950196019701980199020002010 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 Dollars per gallon (in 1993 dollars)

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

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

17. 1 ft 2 of collector = 1 gallon of hot water 1 person uses about 20 gallons/day

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

19. Passive Thermal Mass House

21. Passive Solar Heater

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

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

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

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

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

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

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

32. We live at about 40 o N and receive about 600 W /m 2 So over this 8 hour day one receives: 8 hr x 600 W /m 2 = 4800 W-hr /m 2 = 4.8 kW-hr / m 2 4.8 kW-hr / m 2 is equivalent to 0.13 gal of gasoline For 1000 ft 2 of horizontal area (typical roof area) this is equivalent to 12 gallons of gas or about 450 kW-h Solar Energy Calculation

33. Photovoltaic Array

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

36. Roof Options Solar Cells Panels of Solar Cells

37. Solar Cell Roof

38. Moderate net energy Moderate environmental Impact No CO 2 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 AdvantagesDisadvantages Trade-Offs Solar Energy for High-Temperature Heat and Electricity

39. Solar Steam Generator Barstow, California

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

41. Moderate to high net energy High efficiency (80%) Large untapped potential Low-cost electricity Long life span No CO 2 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 CO 2 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 AdvantagesDisadvantages Trade-Offs Large-Scale Hydropower

42. Producing Electricity from Wind

43. Wind Turbine Power cable Electrical generator Gearbox

46. 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) Basics of Wind Energy

47. Kinetic Energy (of wind) is: 1/2 * mass * velocity 2 KE = 1/2 mv 2 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= mv 2 *v = mv 3 So Power that can be extracted from the wind goes as velocity cubed (v 3 ) Basics of Wind Energy

48. Power going as v 3 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 /m 2 = 0.0006 v 3 Basics of Wind Energy

49. 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/m 2 Which is equal to 600 W/m 2 This is identical to average solar power per square meter at our latitude. Sample Wind Problem

50. Example calculation: Windmill efficiency = 42% Average wind speed = 10 m/s (20 mph) Power * efficiency = 0.0006 x 1000 x 0.42 = 250 W/m 2 250 W/m 2 / 1000 W/kW = 0.25 kW/m 2 Electricity generated is then 0.25 kW-h/m 2 If wind blows 24 hours per day then annual electricity generated would be about 2200 kW-h/m 2 (0.25 kW-h/m 2 x 24h/d x 365d/yr = 2190kW-h/m 2 ) Sample Wind Problem

51. But, on average, the wind velocity is only this high about 10% of the time. Therefore a typical annual yield is about 220 kW-h/m 2 Sample Wind Problem

52. To Generate 10,000 kWh annual then from a 20 mph wind that blows 10% of the time Windmill area = 10,000 kW-h/220 kW-h/m 2 = 45 /m 2 Make a circular disk of diameter about 8 meters This is not completely out of the question for some homes Even a small windmill (2 meters) can be effective. Sample Wind Problem

53. 20 mph 10% of the time 2500 kW-h annually 40 mph 10% of the time 20000 kW-h annually 20 mph 50% of the time 12500 kW-h annually 4 small windmills at 20 mph 10% of the time 10000 kW-h annually Sample Wind Problem

54. Wind Farm

56. Moderate to high net energy High efficiency Moderate capital cost Low electricity cost (and falling) Very low environmental impact No CO 2 emissions Quick construction Easily expanded Land below turbines can be used to grow crops or graze livestock Steady winds needed Backup systems when needed winds are low High land use for wind farm Visual pollution Noise when located near populated areas May interfere in flights of migratory birds and kill birds of prey AdvantagesDisadvantages Trade-Offs Wind Power

57. Producing Energy from Biomass  Biomass and biofuels  Biomass plantations  Crop residues  Animal manure  Biogas  Ethanol  Methanol

58. High octane Some reduction in CO 2 emissions Lower total air Pollution (30-40%) Can be made from natural gas, agricultural wastes, sewage sludge, and garbage Can be used to produce H 2 for fuel cells Large fuel tank needed Half the driving range Corrodes metal, rubber, plastic High CO 2 emissions if made from coal Expensive to produce Hard to start in cold weather AdvantagesDisadvantages Trade-Offs Methanol Fuel

59. High octane Some reduction in CO 2 emission Reduced CO emissions Can be sold as gasohol Potentially renewable Large fuel tank needed Lower driving range Net energy loss Much higher cost Corn supply limited May compete with growing food on cropland Higher NO emission Corrosive Hard to start in colder weather AdvantagesDisadvantages Trade-Offs Ethanol Fuel

60. Large potential supply in some areas Moderate costs No net CO 2 increase if harvested and burned sustainably Plantation can be located on semiarid land not needed for crops Plantation can help restore degraded lands Can make use of agricultural, timber, and urban wastes Nonrenewable if harvested unsustainably Moderate to high environmental impact CO 2 emissions if harvested and burned unsustainably Low photosynthetic efficiency Soil erosion, water pollution, and loss of wildlife habitat Plantations could compete with cropland Often burned in inefficient and polluting open fires and stoves AdvantagesDisadvantages Trade-Offs Solid Biomass

61. Geothermal Energy  Geothermal heat pumps  Geothermal exchange  Dry and wet steam  Hot water  Molten rock (magma)  Hot dry-rock zones

62. Geothermal Power Plant-Geysers, California

64. Covers an area of 70 square kilometers Heat is recovered from the top 2.0 kilometer of crust In this region the temperature is: 240 o C The mean annual surface temperature is: 15 o C The specific heat of the rock is: 2.5 J/cm 3 o C (specific heat is usually expressed in J/g o C) Overall 2 % of the total available thermal energy in this region heats water for steam. The Geysers Geothermal Site

65. How many years can this source provide power for electricity generation at the rate of 2000 MW-yr? (Total Capacity required is rate divided by efficiency) Total Capacity required is 2000 MW-yr/0.02 = 100,000 MW-yr 1 J/s = 1 W; 1 x 10 6 W = 1 MW; 1 yr = 3.15 x 10 7 s 100,000 MW-yr = 1 x 10 5 MWyr 1 x 10 5 MW-yr * 1 x 10 6 W/MW = 1 x 10 11 W-yr 1 x 10 11 W -yr * 3.15 x 10 7 s/yr = 3.15 x 10 18 W-s = 3.15 x 10 18 W-s * 1 J/ W-s = 3.15 x 10 18 J (each year) The Geysers Geothermal Site

66. Volume of rock = 70 km 2 x 2 km = 140 km 3 Change in Temperature ( D T) = 240 o C – 15 o C = 225 o C Heat content (Q) = Volume * specific heat * D T Q = 140 km 3 * 10 15 cm 3 /km 3 * 2.5 J/(cm 3 o C)*225 o C = 8x10 19 J(Total Energy) The Geysers Geothermal Site

67. Hence the lifetime is: Total Energy/ Energy used in a year = Lifetime of Energy Source 8x10 19 J / 3.15 x 10 18 J/yr = 26 yr This shows that we can use this geothermal resource for 26 yr at that rate, after that it is used up. The Geysers Geothermal Site

68. Geothermal Power Plants Dry Steam Flash Steam Binary Cycle

70. Geysers dry steam field, in northern California

72. Binary Plant Soda Lake, Nevada

74. East Mesa, California Flash Steam Plant

75. Hybrid Binary and Flash Plant Big Island of Hawaii

78. Very high efficiency Moderate net energy at accessible sites Lower CO 2 emissions than fossil fuels Low cost at favorable sites Low land use Low land disturbance Moderate environmental impact Scarcity of suitable sites Depleted if used too rapidly CO 2 emissions Moderate to high local air pollution Noise and odor (H 2 S) Cost too high except at the most concentrated and accessible source AdvantagesDisadvantages Trade-Offs Geothermal Fuel

79. MaterialEnergy Density(kW-h/kg) Gasoline 14 Lead Acid Batteries 0.04 Hydro-storage 0.3 / m 3 Flywheel, Steel 0.05 Flywheel, Carbon Fiber 0.2 Flywheel, Fused Silica 0.9 Hydrogen 38 Compressed Air 2 / m 3 Energy Density of Some Materials

80. The Hydrogen Revolution  Extracting hydrogen efficiently  Storing hydrogen  Fuel cells  Environmentally friendly hydrogen

81. The Hydrogen Revolution Utilization Electric utility Transportation Commercial/Residential Industrial Storage Gas and solids Transport Vehicles and pipeline Photo- conversion Electrolysis Reforming Hydrogen Production Electricity Generation Primary Energy Sources Sunlight Fossil fuels Biomass Wind

82. Entering the Age of Decentralized Micropower  Decentralized power systems  Micropower systems

83. Small modular units Fast factory production Fast installation (hours to days) Can add or remove modules as needed High energy efficiency (60–80%) Low or no CO 2 emissions Low air pollution emissions Reliable Easy to repair Much less vulnerable to power outages Increase national security by dispersal of targets Useful anywhere Especially useful in rural areas in developing countries with no power Can use locally available renewable energy resources Easily financed (costs included in mortgage and commercial loan) Decentralized power systems

84. Bioenergy Power plants Wind farm Small solar cell power plants Fuel cells Solar cell rooftop systems Commercial Microturbines Industrial Transmission and distribution system Residential Small wind turbine Rooftop solar cell arrays

85. Wind: 4.3 cents per kWh Coal: 6.2 cents per kWh Photovoltaics: 16.0 cents per kWh Advanced Gas Turbine: 4.6 cents per kWh Price Comparison from 1998 Study Leveled Costs: (includes start-up costs)

86. Solutions: A Sustainable Energy Strategy

87. Drive a car that gets at least 15 kilometers per liter (35 miles per gallon) and join a carpool. Use mass transit, walking, and bicycling. Super insulate your house and plug all air leaks. Turn off lights, TV sets, computers, and other electronic equipment when they are not in use. Wash laundry in warm or cold water. Use passive solar heating. For cooling, open windows and use ceiling fans or whole-house attic or window fans. Turn thermostats down in winter and up in summer. Buy the most energy-efficient homes, lights, cars, and appliances available. Turn down the thermostat on water heaters to 43-49ºC (110-120ºF) and insulate hot water heaters and pipes. What Can You Do? Energy Use ad Waste