Energy Efficiency and Renewable Energy

Transcription

1 LIVING IN THE ENVIRONMENT, 18e G. TYLER MILLER SCOTT E. SPOOLMAN 16 Energy Efficiency and Renewable Energy

2 Core Case Study: The Astounding Potential for Wind Power in the U.S. Wind energy wind farms convert to electrical energy Wind power is inexhaustible Could meet electricity needs of the lower 48 states Texas and California are top producers

3 Electrical generator Gearbox Power cable Wind turbine Fig. 16-1a, p. 402

4 Fig. 16-1b, p. 402

5 16-1 Why Is Energy Efficiency an Important Energy Resource? Improvements in energy efficiency could save at least a third of the energy used in the world and up to 43% of the energy used in the United States We have a variety of technologies for sharply increasing the energy efficiency of industrial operations, motor vehicles, appliances, and buildings

6 We Use Energy Inefficiently Energy efficiency How much useful work we get from each unit energy Advantages of reducing energy waste Usually the cheapest way to provide more energy Reduces pollution and degradation Slows global warming Increases economic and national security

7 We Use Energy Inefficiently (cont d.) Four widely used devices that waste energy Incandescent light bulb Motor vehicle with internal combustion engine Nuclear power plant Coal-fired power plant

8 Energy Inputs System Outputs 9% 7% 85% U. S. economy 41% 43% 8% 3% Nonrenewable fossil fuels Nonrenewable nuclear Renewable (hydropower, geothermal, wind, solar, biomass) Useful energy Petrochemicals Unavoidable energy loss Energy waste Fig. 16-2, p. 403

9 Solutions Improving Energy Efficiency Prolongs fossil fuel supplies Reduces oil imports and improves energy security Very high net energy yield Low cost Reduces pollution and environmental degradation Buys time to phase in renewable energy Creates local jobs Fig. 16-4, p. 404

10 We Can Improve Energy Efficiency in Industry and Utilities Cogeneration Combined heat and power (CHP) Two forms of energy from same fuel source Replace energy-wasting electric motors Recycle materials Switch from low-efficiency incandescent lighting to higher-efficiency fluorescent and LED lighting

11 Case Study: Saving Energy and Money with a Smarter Electrical Grid Current electrical grid system outdated and wasteful Smart grid Ultra-high-voltage Super-efficient transmission lines Digitally controlled Responds to local changes in demand and supply Easier to buy renewable energy

12 We Can Improve Energy Efficiency and Save Money in Transportation Hidden prices in gasoline Should be $12/gallon Car manufacturers and oil companies lobby to prevent laws to raise fuel taxes Build or expand mass transit and high speed rail Encourage biking

13 More Energy-Efficient Vehicles Are on the Way Superefficient and ultralight cars Gasoline-electric hybrid car Plug-in hybrid electric vehicle Energy-efficient diesel car Electric vehicle with a fuel cell

14 Conventional hybrid Fuel tank Plug-in hybrid Fuel tank Internal combustion engine Transmission Electric motor Battery Internal combustion engine Transmission Electric motor Battery Stepped Art Fig 16-6, p. 406

15 We Can Design Buildings That Save Energy and Money Green architecture Living or green roofs With specially designed soil and vegetation Superinsulation No need for heating system U.S. Green Building Council s Leadership in Energy and Environmental Design (LEED)

16 Fig. 16-7, p. 408

17 We Can Save Money and Energy in Existing Buildings Conduct an energy audit: Insulate and plug leaks Use energy-efficient windows Stop other heating and cooling losses Heat houses more efficiently Use energy-efficient appliances Use energy-efficient lighting Use motion sensors to turn lights on and off

18 Fig. 16-9, p. 410

19 Attic Hang reflective foil near roof to reflect heat. Use house fan. Be sure attic insulation is at least 30 centimeters (12 inches). Bathroom Install water-saving toilets, faucets, and shower heads. Repair water leaks promptly. Kitchen Use microwave rather than stove or oven as much as possible. Run only full loads in dishwasher and use low- or no-heat drying. Clean refrigerator coils regularly. Basement or utility room Use front-loading clothes washer. If possible run only full loads with warm or cold water. Hang clothes on racks for drying. Run only full loads in clothes dryer and use lower heat setting. Set water heater at 140 if dishwasher is used and 120 or lower if no dishwasher is used. Use water heater thermal blanket. Insulate exposed hot water pipes. Regularly clean or replace furnace filters. Outside Plant deciduous trees to block summer sun and let in winter sunlight. Other rooms Use compact fluorescent lightbulbs or LEDs and avoid using incandescent bulbs wherever possible. Turn off lights, computers, TV, and other electronic devices when they are not in use. Use high efficiency windows; use insulating window covers and close them at night and on sunny, hot days. Set thermostat as low as you can in winter and as high as you can in summer. Weather-strip and caulk doors, windows, light fixtures, and wall sockets. Keep heating and cooling vents free of obstructions. Keep fireplace damper closed when not in use. Use fans instead of, or along with, air conditioning. Stepped Art Fig , p. 411

20 Why Are We Still Wasting So Much Energy and Money? Energy remains artificially cheap Government subsidies Tax breaks Prices don t include true cost Few large and long-lasting incentives Government rebates Low-interest loans Lack of education

21 We Can Use Renewable Energy to Provide Heat and Electricity Renewable energy Solar energy Geothermal energy Renewable energy will be cheaper if we eliminate: Inequitable subsidies Inaccurate prices Artificially low pricing of nonrenewable energy

22 Available Energy Flow (exajoules per year) World energy use (2010) 527 Direct solar >1,000 Wind 600 Geothermal 500 Biomass <250 Hydropower 50 Ocean <1 Fig , p. 412

23 16-3 What Are the Advantages and Disadvantages of Solar Energy? Passive and active solar heating systems can heat water and buildings effectively The costs of using direct sunlight to produce high-temperature heat and electricity are coming down

24 We Can Heat Buildings and Water with Solar Energy Passive solar heating system Absorbs and stores heat from the sun directly within a well-insulated structure Active solar heating system Captures energy from the sun in a heatabsorbing fluid

25 Trade-Offs Passive or Active Solar Heating Advantages Net energy is moderate (active) to high (passive) Disadvantages Need access to sun 60% of time during daylight Very low emissions of CO 2 and other air pollutants Very low land disturbance Sun can be blocked by trees and other structures High installation and maintenance costs for active systems Moderate cost (passive) Need backup system for cloudy days Fig , p. 415

26 We Can Cool Buildings Naturally Technologies available Open windows when cooler outside Use fans Superinsulation and high-efficiency windows Overhangs or awnings on windows Light-colored roof Geothermal pumps

27 We Can Concentrate Sunlight to Produce High-Temperature Heat and Electricity Solar thermal systems Collect sunlight to boil water, generate electricity 1% of world deserts could supply all the world s electricity Require large amounts of water Wet cooling Dry cooling Low net energy yields

28 Fig , p. 416

29 Trade-Offs Solar Thermal Systems Advantages High potential for growth No direct emissions of CO 2 and other air pollutants Lower costs with natural gas turbine backup Source of new jobs Disadvantages Low net energy and high costs Needs backup or storage system on cloudy days Can disrupt desert ecosystems Fig , p. 416

30 We Can Use Solar Cells to Produce Electricity Photovoltaic (PV) cells Convert solar energy to electric energy Design of solar cells Sunlight hits cells and releases electrons into wires What are the benefits of using solar cells?

31 We Can Use Solar Cells to Produce Electricity (cont d.) Key problems High cost of producing electricity Need to be located in sunny desert areas Fossil fuels used in production Solar cells contain toxic materials Cost could drop with: Mass production and new designs Government subsidies and tax breaks

32 Fig , p. 418

33 Fig , p. 418

34 Trade-Offs Solar Cells Advantages Medium net energy yield Little or no direct emissions of CO 2 and other air pollutants Easy to install, move around, and expand as needed Competitive cost for newer cells Disadvantages Need access to sun Some designs have low net energy yield Need electricity storage system or backup Costs high for older systems but dropping rapidly Solar-cell power plants could disrupt desert ecosystems Fig , p. 419

35 16-4 What Are the Advantages and Disadvantages of Using Hydropower We can use water flowing over dams, tidal flows, and ocean waves to generate electricity However, environmental concerns and limited availability of suitable sites may limit the use of these energy resources

36 We Can Produce Electricity from Falling and Flowing Water Hydropower Uses kinetic energy of moving water Indirect form of solar energy World s leading renewable energy source used to produce electricity What are the advantages and disadvantages? Micro-hydropower generators: floating turbines

37 Trade-Offs Large-Scale Hydropower Advantages High net energy yield Large untapped potential Low-cost electricity Low emissions of CO 2 and other air pollutants in temperate areas Disadvantages Large land disturbance and displacement of people High CH 4 emissions from rapid biomass decay in shallow tropical reservoirs Disrupts downstream aquatic ecosystems Fig , p. 420

38 We Can Use Tides and Waves to Produce Electricity Produce electricity from flowing water Ocean tides and waves in coastal bays and estuaries Power systems are limited Few suitable sites High costs Equipment damaged by storms and corrosion

39 16-5 What Are the Advantages and Disadvantages of Using Wind Power? When we include the environmental costs of using energy resources in their market prices, wind power is the least expensive and least polluting way to produce electricity

40 Using Wind to Produce Electricity Is an Important Step toward Sustainability Tall, long-blade turbines can extract more energy from the wind Rapidly growing power source U.S., Europe, and China Future is offshore wind farms Wind power has potential to produce 40 times of the world s current electricity used

41 Using Wind to Produce Electricity Is an Important Step (cont d.) Wind is abundant, widely distributed, and inexhaustible High net energy yield Drawbacks: Largest potential areas are usually rural Winds can die down need backup power source

42 Trade-Offs Wind Power Advantages High net energy yield Widely available Low electricity cost Little or no direct emissions of CO 2 and other air pollutants Easy to build and expand Disadvantages Needs backup or storage system when winds die down Visual pollution for some people Low-level noise bothers some people Can kill birds if not properly designed and located Fig , p. 423

43 16-6 Advantages and Disadvantages of Using Biomass as an Energy Source Solid biomass is a renewable resource for much of the world s population, but burning it faster than it is replenished produces a net gain in atmospheric greenhouse gases

44 16-6 Advantages and Disadvantages of Biomass as an Energy Source (cont d.) We can use liquid biofuels derived from biomass to lessen our dependence on oilbased fuels, but creating biofuel plantations can: Degrade soil and biodiversity Increase greenhouse gas emissions Lead to higher food prices

45 We Can Produce Energy by Burning Solid Biomass Biomass Plant materials and animal waste we can burn or turn into biofuels Production of solid mass fuel Plant fast-growing trees; biomass plantations Collect crop residues and animal manure What are the advantages and disadvantages of biomass energy?

46 Trade-Offs Solid Biomass Advantages Widely available in some areas Moderate costs Medium net energy yield No net CO 2 increase if harvested, burned, and replanted sustainably Plantations can help restore degraded lands Disadvantages Contributes to deforestation Clear-cutting can cause soil erosion, water pollution, and loss of wildlife habitat Can open ecosystems to invasive species Increases CO 2 emissions if harvested and burned unsustainably Fig , p. 424

47 Case Study: Is Biodiesel the Answer? Biodiesel Produced from vegetable oil European Union countries produce 95% of the world s biodiesel Crops require large amounts of land Production requires fossil fuels

48 Case Study: Is Ethanol the Answer? Ethanol Can be made from sugarcane, corn, switchgrass, and various wastes United States largest producer Made from corn; low net energy yield Brazil second Sugarcane has medium net energy yield Cellulosic ethanol Produced from cellulose

49 Case Study: Is Ethanol the Answer? (cont d.) Problems with cellulosic ethanol Chemical processes still being developed Growing enough switchgrass would require too much land Evaluating use of algae and bacteria

50 Trade-Offs Liquid Biofuels Advantages Reduced CO 2 emissions for some crops Medium net energy yield for biodiesel from oil palms Medium net energy yield for ethanol from sugarcane Disadvantages Fuel crops can compete with food crops for land and raise food prices Fuel crops can be invasive species Low net energy yield for corn ethanol and for biodiesel from soybeans Higher CO 2 emissions from corn ethanol Fig , p. 426

51 16-7 What Are the Advantages and Disadvantages of Geothermal Energy? Geothermal energy has great potential for supplying many areas with heat and electricity, and has a generally low environmental impact However, the sites where it can be produced economically are limited

52 We Can Get Energy by Tapping the Earth s Internal Heat With geothermal energy, heat is stored in: Soil Underground rocks Fluids in the earth s mantle Geothermal heat pump system Energy efficient and reliable Environmentally clean Cost effective to heat or cool a space

53 We Can Get Energy by Tapping the Earth s Internal Heat (cont d.) Hydrothermal reservoirs Drill wells and extract various steams, water U.S. is the world s largest producer Geothermal energy problems High cost of tapping hydrothermal reservoirs Dry- or wet-steam geothermal reservoirs could be depleted Could create earthquakes

54 2. Heat from underground spins a turbine to power a generator and produce electricity Generator Steam turbine Heat exchanger 3. Steam from turbine condenses to water and is pumped back down to geothermal reservoir Production well Injection well 1. Hot water or steam is pumped under pressure to the surface from underground Geothermal reservoir Fig a, p. 428

55 Fig b, p. 428

56 Trade-Offs Geothermal Energy Advantages Medium net energy yield and high efficiency at accessible sites Disadvantages High cost except at concentrated and accessible sites Lower CO 2 emissions than fossil fuels Scarcity of suitable sites Low cost at favorable sites Noise and some CO 2 emissions Fig , p. 430

57 16-8 The Advantages and Disadvantages of Using Hydrogen as an Energy Source Hydrogen is a clean energy source as long as it is not produced with the use of fossil fuels However, it has a negative net energy yield

58 Will Hydrogen Save Us? Hydrogen as a fuel Eliminates most of the air pollution problems Reduces threats of global warming

59 Will Hydrogen Save Us? Some challenges Chemically locked in water and organic compounds net negative energy yield Expensive fuel cells are the best way to use hydrogen CO 2 levels dependent on method of hydrogen production

60 Hydrogen gas (H 2 ) in Electrons Anode Polymer electrolyte membrane Cathode Water vapor (H 2 O) out Protons Air (O 2 ) in Fig , p. 430

61 Will Hydrogen Save Us? (cont d.) Production and storage of H 2 Must be produced using other sources of energy Hydrogen-powered vehicles prototypes available Can we produce hydrogen on demand? Larger fuel cells fuel-cell stacks

62 Trade-Offs Hydrogen Advantages Can be produced from plentiful water at some sites No CO 2 emissions if produced with use of renewables Good substitute for oil Fuel cell Disadvantages Negative net energy yield CO 2 emissions if produced from carbon-containing compounds High costs create need for subsidies High efficiency in fuel cells Needs H 2 storage and distribution system Fig , p. 432

63 16-9 How Can We Make the Transition to a More Sustainable Energy Future? We can make the transition to a more sustainable energy future by: Greatly improving energy efficiency Using a mix of renewable energy resources Including the environmental and health costs of energy resources in their market prices

64 Choosing Energy Paths General conclusions: Gradual shift to smaller, decentralized micropower systems Combination of increased energy efficiency and regulated use of natural gas will be the best way to transition to renewable energy Because fossil fuels are cheap we will continue to use them

65 Bioenergy power plants Wind farm Small solar-cell power plants Fuel cells Rooftop solarcell arrays Solar-cell rooftop systems Smart electrical and distribution system Commercial Residential Small wind turbine Industrial Microturbines Stepped Art Fig , p. 433

66 Economics, Politics, Education, and Sustainable Energy Resources Government strategies: Keep the prices of selected energy resources artificially low to encourage their use Keep energy prices artificially high for selected resources to discourage their use Consumer education

67 Fig , p. 434

68 Three Big Ideas We should evaluate energy resources on the basis of: Their potential supplies Their net energy yields Environmental and health impacts of using them

69 Three Big Ideas (cont d.) By using a mix of renewable energy sources we could drastically reduce pollution, greenhouse gas emissions, and biodiversity losses Solar, wind, flowing water, sustainable biofuels, and geothermal energy

70 Three Big Ideas (cont d.) Making the transition to a more sustainable energy future will require: Sharply increasing energy efficiency Using a mix of environmentally friendly renewable energy resources Including the harmful environmental and health costs of energy resources in their market prices

71 Tying It All Together: Wind Power and Sustainability Relying on a diversity of direct and indirect forms of solar energy: Would implement three principles of sustainability Recycle and reuse materials to reduce consumption of energy Mimic nature s reliance on biodiversity by diversifying energy sources