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Chapter 17. Energy Efficiency and Renewable Energy. REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCY. Energy conservation – the reduction or elimination of unnecessary waste energy. Flow of commercial energy through the U.S. economy. - PowerPoint PPT Presentation
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Chapter 17Chapter 17
Energy Efficiency and Energy Efficiency and Renewable EnergyRenewable Energy
REDUCING ENERGY WASTE AND REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCYIMPROVING ENERGY EFFICIENCY
Energy conservationEnergy conservation – the – the reduction or elimination of reduction or elimination of unnecessary waste unnecessary waste energy.energy.
Flow of commercial Flow of commercial energy through the U.S. energy through the U.S. economy.economy.
84% of all commercial 84% of all commercial energy used in the U.S. is energy used in the U.S. is wasted wasted
41% wasted due to 241% wasted due to 2ndnd law law of thermodynamics.of thermodynamics.
Figure 17-2Figure 17-2
REDUCING ENERGY WASTE AND REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCYIMPROVING ENERGY EFFICIENCY
Four widely used devices waste large amounts of energy:Four widely used devices waste large amounts of energy: Incandescent light bulbIncandescent light bulb: 95% is lost as heat.: 95% is lost as heat. Internal combustion engineInternal combustion engine: 94% of the energy in its fuel is wasted.: 94% of the energy in its fuel is wasted. Nuclear power plantNuclear power plant: 92% of energy is wasted through nuclear fuel : 92% of energy is wasted through nuclear fuel
and energy needed for waste management.and energy needed for waste management. Coal-burning power plantCoal-burning power plant: 66% of the energy released by burning : 66% of the energy released by burning
coal is lost.coal is lost.
Why do we waste so much energy?Why do we waste so much energy?
Low-priced fossil fuels and few government tax breaks or other Low-priced fossil fuels and few government tax breaks or other financial incentives for saving energy promote energy waste.financial incentives for saving energy promote energy waste.
Fig. 17-3, p. 386
Solutions
Reducing Energy Waste
Prolongs fossil fuel supplies
Reduces oil imports
Very high net energy
Low cost
Reduces pollution and environmental degradation
Buys time to phase in renewable energy
Less need for military protection of Middle East oil resources
Creates local jobs
Net Energy Efficiency: Net Energy Efficiency: Honest AccountingHonest Accounting
Comparison of net energy Comparison of net energy efficiency for two types of efficiency for two types of space heating.space heating.
Figure 17-4Figure 17-4
WAYS TO IMPROVE ENERGY EFFICIENCYWAYS TO IMPROVE ENERGY EFFICIENCY
We can save energy in…We can save energy in… Industry Industry
Produce both heat and electricity from one energy source Produce both heat and electricity from one energy source Use more energy-efficient electric motors and lighting.Use more energy-efficient electric motors and lighting.
TransportationTransportation Increase fuel efficiency Increase fuel efficiency Make vehicles from lighter and stronger materials.Make vehicles from lighter and stronger materials.
Construction/BuildingsConstruction/Buildings Get heat from the sun, Get heat from the sun, Super-insulate buildingsSuper-insulate buildings Use plant covered green roofs.Use plant covered green roofs. Plug leaksPlug leaks Use energy efficient heating and cooling systems, appliances, and lightingUse energy efficient heating and cooling systems, appliances, and lighting
Passive Solar HousePassive Solar House
The heating bill for this energy-efficient passive solar radiation office in The heating bill for this energy-efficient passive solar radiation office in Colorado is $50 a year.Colorado is $50 a year.
Figure 17-1Figure 17-1
Strawbale HouseStrawbale House
Strawbale is a superinsulator that is made from bales of low-Strawbale is a superinsulator that is made from bales of low-cost straw covered with plaster or adobe. Depending on the cost straw covered with plaster or adobe. Depending on the thickness of the bales, its strength exceeds standard thickness of the bales, its strength exceeds standard construction.construction.
Figure 17-9Figure 17-9
Living RoofsLiving Roofs
Roofs covered with plants Roofs covered with plants have been used for have been used for decades in Europe and decades in Europe and Iceland.Iceland.
These roofs are built from a These roofs are built from a blend of light-weight blend of light-weight compost, mulch and compost, mulch and sponge-like materials that sponge-like materials that hold water.hold water.
Figure 17-10Figure 17-10
Saving Energy in Existing BuildingsSaving Energy in Existing Buildings
About one-third of the heated air in typical U.S. homes and About one-third of the heated air in typical U.S. homes and buildings escapes through closed windows and holes and buildings escapes through closed windows and holes and cracks.cracks.
Figure 17-11Figure 17-11
USING RENEWABLE SOLAR ENERGY TO USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ELECTRICITYPROVIDE HEAT AND ELECTRICITY
A variety of renewable-energy resources are available but A variety of renewable-energy resources are available but their use has been hindered by a lack of government support their use has been hindered by a lack of government support compared to nonrenewable fossil fuels and nuclear power.compared to nonrenewable fossil fuels and nuclear power.
Direct solar Direct solar Moving water Moving water Wind Wind GeothermalGeothermal
Solar CellsSolar Cells
It is possible to get electricity from solar cells that convert It is possible to get electricity from solar cells that convert sunlight into electricity.sunlight into electricity.
Can be attached like shingles on a roof.Can be attached like shingles on a roof. Can be applied to window glass as a coating.Can be applied to window glass as a coating. Can be mounted on racks almost anywhere.Can be mounted on racks almost anywhere.
Heating Buildings and Water with Solar EnergyHeating Buildings and Water with Solar Energy
We can heat buildings by orienting them toward the sun or We can heat buildings by orienting them toward the sun or by pumping a liquid such as water through rooftop collectors.by pumping a liquid such as water through rooftop collectors.
Figure 17-12Figure 17-12
Passive Solar HeatingPassive Solar Heating
Passive solar heating system Passive solar heating system absorbs and stores heat from absorbs and stores heat from the sun directly within a the sun directly within a structure without the need for structure without the need for pumps to distribute the heat.pumps to distribute the heat.
Figure 17-13Figure 17-13
Fig. 17-13, p. 396
Direct Gain
Summer sunHot air
Warm air
Super-insulated windows
Winter sun
Cool air
Earth tubes
Ceiling and north wall heavily insulated
Fig. 17-13, p. 396
Greenhouse, Sunspace, or Attached Solarium
Summer cooling vent
Warm air
Insulated windows
Cool air
Fig. 17-13, p. 396
Earth Sheltered
Reinforced concrete, carefully waterproofed walls and roof
Triple-paned or superwindowsEarth
Flagstone floor for heat storage
Fig. 17-14, p. 396
Trade-Offs
Passive or Active Solar Heating
Advantages Disadvantages
Energy is free Need access to sun 60% of time
Net energy is moderate (active) to high (passive)
Sun blocked by other structures
Need heat storage system
Quick installation
No CO2 emissions
Very low air and water pollution High cost (active)
Very low land disturbance (built into roof or window)
Active system needs maintenance and repair
Moderate cost (passive)
Active collectors unattractive
Cooling Houses NaturallyCooling Houses Naturally
We can cool houses by:We can cool houses by: Superinsulating them.Superinsulating them. Taking advantages of breezes. Taking advantages of breezes. Shading them.Shading them. Having light colored or green roofs.Having light colored or green roofs. Using geothermal cooling.Using geothermal cooling.
Using Solar Energy to Generate High-Using Solar Energy to Generate High-Temperature Heat and ElectricityTemperature Heat and Electricity
Large arrays of solar Large arrays of solar collectors in sunny collectors in sunny deserts can produce deserts can produce high-temperature heat to high-temperature heat to spin turbines for spin turbines for electricity, but costs are electricity, but costs are high.high.
Figure 17-15Figure 17-15
Producing Electricity with Solar CellsProducing Electricity with Solar Cells
Solar cells convert Solar cells convert sunlight to electricity.sunlight to electricity.
Their costs are high, but Their costs are high, but expected to fall.expected to fall.
Figure 17-16Figure 17-16
Producing Electricity with Solar CellsProducing Electricity with Solar Cells
Photovoltaic (PV) cells can provide electricity for a house of Photovoltaic (PV) cells can provide electricity for a house of building using solar-cell roof shingles.building using solar-cell roof shingles.
Figure 17-17Figure 17-17
Producing Electricity with Solar CellsProducing Electricity with Solar Cells
Solar cells can be used in Solar cells can be used in rural villages with ample rural villages with ample sunlight who are not sunlight who are not connected to an electrical connected to an electrical grid.grid.
Figure 17-18Figure 17-18
Fig. 17-19, p. 399
Trade-OffsSolar Cells
Advantages Disadvantages
Fairly high net energy Need access to sun
Work on cloudy daysLow efficiency
Quick installation
Need electricity storage system or backup
Easily expanded or moved
No CO2 emissions
High land use (solar-cell power plants) could disrupt desert areas
Low environmental impact
Last 20–40 years
Low land use (if on roof or built into walls or windows)
High costs (but should be competitive in 5–15 years)
Reduces dependence on fossil fuels DC current must be converted
to AC
Producing Electricity with Solar CellsProducing Electricity with Solar Cells
PRODUCING ELECTRICITY FROM THE PRODUCING ELECTRICITY FROM THE WATER CYCLEWATER CYCLE
Water flowing in rivers and streams can be trapped in Water flowing in rivers and streams can be trapped in reservoirs behind dams and released as needed to spin reservoirs behind dams and released as needed to spin turbines and produce electricity.turbines and produce electricity.
There is little room for expansion in the U.S. – Dams and There is little room for expansion in the U.S. – Dams and reservoirs have been created on 98% of suitable rivers.reservoirs have been created on 98% of suitable rivers.
Fig. 17-20, p. 400
Trade-OffsLarge-Scale Hydropower
Advantages Disadvantages
Moderate to high net energy High construction costs
Large untapped potential
High environmental impact from flooding land to form a reservoir
High efficiency (80%)
High CO2 emissions from biomass decay in shallow tropical reservoirs
Low-cost electricity
Long life span
No CO2 emissions during operation in temperate areas
Floods natural areas behind dam
May provide flood control below dam
Converts land habitat to lake habitat
Danger of collapse
Provides water for year-round irrigation of cropland
Uproots peopleDecreases fish harvest below dam
Reservoir is useful for fishing and recreation
Decreases flow of natural fertilizer (silt) to land below dam
PRODUCING ELECTRICITY FROM THE PRODUCING ELECTRICITY FROM THE WATER CYCLEWATER CYCLE
Ocean tides and waves and temperature differences Ocean tides and waves and temperature differences between surface and bottom waters in tropical waters are between surface and bottom waters in tropical waters are not expected to provide much of the world’s electrical needs.not expected to provide much of the world’s electrical needs.
Only two large tidal energy dams are currently operating: Only two large tidal energy dams are currently operating: one in La Rance, France and Nova Scotia’s bay of Fundy one in La Rance, France and Nova Scotia’s bay of Fundy where the tidal amplitude can be as high as 16 meters (63 where the tidal amplitude can be as high as 16 meters (63 feet).feet).
PRODUCING ELECTRICITY FROM WINDPRODUCING ELECTRICITY FROM WIND Wind power is the world’s most “promising” energy Wind power is the world’s most “promising” energy
resource resource AbundantAbundant InexhaustibleInexhaustible widely distributedwidely distributed ““Cheap”Cheap” CleanClean emits no greenhouse gasesemits no greenhouse gases
Much of the world’s potential for wind power Much of the world’s potential for wind power remains untapped.remains untapped.
Capturing only 20% of the wind energy at the Capturing only 20% of the wind energy at the world’s best energy sites could meet all the world’s world’s best energy sites could meet all the world’s energy demands.energy demands.
PRODUCING ELECTRICITY PRODUCING ELECTRICITY FROM WINDFROM WIND
Wind turbines can be used individually to produce Wind turbines can be used individually to produce electricity. They are also used interconnected in arrays electricity. They are also used interconnected in arrays on wind farms.on wind farms.
Figure 17-21Figure 17-21
WIND POWER VIDEOSWIND POWER VIDEOSWind Power Wind Power
All AlongAll Along
Vertical Axis Windmill
(New Mexico)
Wind PowerWind PowerIssuesIssues
Types of Wind Types of Wind TurbinesTurbines
Windmills in TX
Windmills in CA
VAWT(California)
Helix Wind Turbine
Wind Farm Noise
Wind Turbine Collapse
(Denmark)
Birds & Wind
Turbines
PRODUCING ELECTRICITY FROM WINDPRODUCING ELECTRICITY FROM WIND
The United States once led the wind power industry, but The United States once led the wind power industry, but Europe now leads this rapidly growing business.Europe now leads this rapidly growing business.
The U.S. government lacked subsidies, tax breaks and other The U.S. government lacked subsidies, tax breaks and other financial incentives.financial incentives.
European companies manufacture 80% of the wind turbines European companies manufacture 80% of the wind turbines sold in the global marketsold in the global market
The success has been aided by strong government subsidies.The success has been aided by strong government subsidies.
Fig. 17-22, p. 403
Trade-Offs
Wind Power
Advantages Disadvantages
Moderate to high net energy Steady winds needed
Backup systems needed when winds are low
High efficiency
Moderate capital cost
Low electricity cost (and falling)High land use for wind farm
Very low environmental impact
No CO2 emissions Visual pollution
Quick constructionNoise when located near populated areasEasily expanded
Can be located at sea
Land below turbines can be used to grow crops or graze livestock
May interfere in flights of migratory birds and kill birds of prey
PRODUCING ENERGY PRODUCING ENERGY FROM BIOMASSFROM BIOMASS
Plant materials and animal Plant materials and animal wastes can be burned to wastes can be burned to provide heat or electricity or provide heat or electricity or converted into gaseous or converted into gaseous or liquid biofuels.liquid biofuels.
Figure 17-23Figure 17-23
PRODUCING ENERGY FROM BIOMASSPRODUCING ENERGY FROM BIOMASS
The scarcity of fuelwood The scarcity of fuelwood causes people to make causes people to make fuel briquettes from cow fuel briquettes from cow dung in India. This dung in India. This deprives soil of plant deprives soil of plant nutrients.nutrients.
Figure 17-24Figure 17-24
Fig. 17-25, p. 405
Trade-OffsSolid Biomass
Advantages Disadvantages
Large potential supply in some areas
Nonrenewable if harvested unsustainably
Moderate costs Moderate to high environmental impact
No net CO2 increase if harvested and burned sustainably
CO2 emissions if harvested and burned unsustainably
Low photosynthetic efficiencyPlantation can be located on semiarid land not needed for crops
Soil erosion, water pollution, and loss of wildlife habitat
Plantation can help restore degraded lands
Plantations could compete with cropland
Often burned in inefficient and polluting open fires and stoves
Can make use of agricultural, timber, and urban wastes
GEOTHERMAL ENERGYGEOTHERMAL ENERGY
Geothermal energy consists of heat stored in soil, Geothermal energy consists of heat stored in soil, underground rocks, and fluids in the earth’s mantle.underground rocks, and fluids in the earth’s mantle.
We can use geothermal energy stored in the earth’s mantle We can use geothermal energy stored in the earth’s mantle to heat and cool buildings and to produce electricity.to heat and cool buildings and to produce electricity.
A geothermal heat pump (GHP) can heat and cool a house by A geothermal heat pump (GHP) can heat and cool a house by exploiting the difference between the earth’s surface and exploiting the difference between the earth’s surface and underground temperatures.underground temperatures.
Geothermal Heat PumpGeothermal Heat Pump
The house is heated in The house is heated in the winter by transferring the winter by transferring heat from the ground into heat from the ground into the house.the house.
The process is reversed The process is reversed in the summer to cool in the summer to cool the house.the house.
Figure 17-31Figure 17-31
GEOTHERMAL ENERGYGEOTHERMAL ENERGY
Deeper more concentrated hydrothermal reservoirs can be Deeper more concentrated hydrothermal reservoirs can be used to heat homes and buildings and spin turbines:used to heat homes and buildings and spin turbines:
Dry steamDry steam: water vapor with no water droplets.: water vapor with no water droplets. Wet steamWet steam: a mixture of steam and water droplets.: a mixture of steam and water droplets. Hot waterHot water: is trapped in fractured or porous rock.: is trapped in fractured or porous rock.
Fig. 17-32, p. 410
Trade-Offs
Geothermal Energy
Advantages Disadvantages
Very high efficiency
Scarcity of suitable sites
Moderate net energy at accessible sites
Depleted if used too rapidly
Lower CO2 emissions than fossil fuels Moderate to high
local air pollutionLow cost at favorable sites
CO2 emissions
Noise and odor (H2S)Low land use
Low land disturbance Cost too high
except at the most concentrated and accessible sources
Moderate environmental impact
A SUSTAINABLE ENERGY STRATEGYA SUSTAINABLE ENERGY STRATEGY
Shifts in the use of commercial energy resources in the U.S. Shifts in the use of commercial energy resources in the U.S. since 1800, with projected changes to 2100.since 1800, with projected changes to 2100.
Figure 17-34Figure 17-34
A SUSTAINABLE ENERGY STRATEGYA SUSTAINABLE ENERGY STRATEGY
A more sustainable energy policy would improve energy A more sustainable energy policy would improve energy efficiency, rely more on renewable energy, and reduce the efficiency, rely more on renewable energy, and reduce the harmful effects of using fossil fuels and nuclear energy.harmful effects of using fossil fuels and nuclear energy.
There will be a gradual shift from large, centralized macropower There will be a gradual shift from large, centralized macropower systems to smaller, decentralized micropower systems.systems to smaller, decentralized micropower systems.
Fig. 17-35, p. 414
Small solar-cell power plantsBioenergy power
plantsWind farm
Rooftop solar cell arrays
Fuel cellsSolar-cell
rooftop systems
Transmission and distribution system
CommercialSmall wind
turbineResidential
Industrial Microturbines
Fig. 17-36, p. 415
More Renewable Energy
Increase renewable energy to 20% by 2020 and 50% by 2050
Provide large subsidies and tax credits for renewable energy
Use full-cost accounting and life-cycle cost for comparing all energy alternatives
Encourage government purchase of renewable energy devices
Greatly increase renewable energy R&D
Reduce Pollution and Health Risk
Cut coal use 50% by 2020
Phase out coal subsidies
Levy taxes on coal and oil use
Phase out nuclear power or put it on hold until 2020
Phase out nuclear power subsidies
Improve Energy Efficiency
Increase fuel-efficiency standards for vehicles, buildings, and appliances
Mandate govern-ment purchases of efficient vehicles and other devices
Provide large tax credits for buying efficient cars, houses, and appliances
Offer large tax credits for invest-ments in energy efficiency
Reward utilities for reducing demand for electricity Encourage indepen-dent power producers Greatly increase energyefficiency research and development
Economics, Politics, Education, and Energy Economics, Politics, Education, and Energy ResourcesResources
Governments can use a combination of subsidies, tax Governments can use a combination of subsidies, tax breaks, rebates, taxes and public education to promote or breaks, rebates, taxes and public education to promote or discourage use of various energy alternatives:discourage use of various energy alternatives:
Can keep prices artificially low to encourage selected energy Can keep prices artificially low to encourage selected energy resources.resources.
Can keep prices artificially high to discourage other energy Can keep prices artificially high to discourage other energy resources.resources.
Emphasize consumer education.Emphasize consumer education.
Fig. 17-37, p. 416
What Can You Do?Energy Use and Waste
• Get an energy audit at your house or office.
• 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.
• Superinsulate 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, up in summer.
• Buy the most energy-efficient homes, lights, cars, and appliances available.
• Turn down the thermostat on water heaters to 43–49°C (110–120°F) and insulate hot water heaters and pipes.