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 Core Case Study The Astounding Potential for Wind Power in the US ID: 723903
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Slide1
16
Energy Efficiency and Renewable EnergySlide2
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
Core Case Study: The Astounding Potential for Wind Power in the U.S.Slide3
Fig. 16-1a, p. 402
Gearbox
Electrical generator
Power cable
Wind turbineSlide4
Fig. 16-1b, p. 402Slide5
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
16-1 Why Is Energy Efficiency an Important Energy Resource?Slide6
Energy efficiency A measure of how much useful work we get from each unit energy we use.
Advantages of reducing energy waste
Usually the cheapest way to provide more energyReduces pollution and degradationSlows global warming
Increases economic and national security
We Use Energy InefficientlySlide7
Four widely used devices that waste energyIncandescent light bulb
Motor vehicle with internal combustion engine
Nuclear power plantCoal-fired power plant
We Use Energy Inefficiently (cont’d.)Slide8
Fig. 16-2, p. 403
Energy Inputs
System
Outputs
9%
7%
41%
85%
U. S. economy
43%
8%
Nonrenewable fossil fuels
Useful energy
Renewable (hydropower, geothermal, wind, solar, biomass)
Energy waste
3%
Petrochemicals
Unavoidable energy loss
Nonrenewable nuclearSlide9
Fig. 16-4, p. 404
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 jobsSlide10
Cogeneration
Involves using combined heat and power (CHP) system
Two forms of energy from same fuel source; 75%-90% efficiency. Replace energy-wasting electric motorsRecycle materialsSwitch from low-efficiency incandescent lighting to higher-efficiency fluorescent and LED lighting
We Can Improve Energy Efficiency in Industry and UtilitiesSlide11
Current electrical grid system – outdated and wastefulSmart grid
Ultra-high-voltage
Super-efficient transmission linesDigitally controlledResponds to local changes in demand and supplyEasier to buy renewable energy
Case Study: Saving Energy and Money with a Smarter Electrical GridSlide12
Hidden prices in gasolineShould be $12/gallon
Car manufacturers and oil companies lobby to prevent laws to raise fuel taxes
Build or expand mass transit and high speed railEncourage biking
We Can Improve Energy Efficiency and Save Money in TransportationSlide13
Superefficient and ultralight carsGasoline-electric hybrid car
Plug-in hybrid electric vehicle
Energy-efficient diesel carElectric vehicle with a fuel cell
More Energy-Efficient Vehicles Are on the WaySlide14
Stepped Art
Conventional hybrid
Fuel tank
Battery
Internal combustion engine
Transmission
Electric motor
Plug-in hybrid
Fuel tank
Battery
Internal combustion engine
Transmission
Electric motor
Fig 16-6, p. 406Slide15
Green architectureLiving or green roofs
With specially designed soil and vegetation
SuperinsulationNo need for heating systemU.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED)
We Can Design Buildings That Save Energy and MoneySlide16
Fig. 16-7, p. 408Slide17
Conduct an energy audit:Insulate and plug leaks
Use energy-efficient windows
Stop other heating and cooling lossesHeat houses more efficientlyUse energy-efficient appliancesUse energy-efficient lighting
Use motion sensors to turn lights on and off
We Can Save Money and Energy in Existing BuildingsSlide18
Fig. 16-9, p. 410Slide19
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.
Bathroom• Install water-saving toilets,
faucets, and shower heads.• Repair water leaks promptly.
Stepped Art
Attic
• Hang reflective foil near
roof to reflect heat.
• Use house fan.
• Be sure attic insulation is
at least 30 centimeters
(12 inches).
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.
Fig. 16-10, p. 411Slide20
1.Energy remains artificially cheapGovernment subsidies
Tax breaks
Prices don’t include true cost2.Few large and long-lasting incentivesGovernment rebatesLow-interest loans
3.Lack of education
Why Are We Still Wasting So Much Energy and Money?Slide21
Renewable energySolar energy
Geothermal energy
Renewable energy will be cheaper if we eliminate:Inequitable subsidiesInaccurate pricesArtificially low pricing of nonrenewable energy
We Can Use Renewable Energy to Provide Heat and ElectricitySlide22
Fig. 16-11, p. 412
Available Energy Flow (
exajoules
per year)
World energy use (2010)
Direct solar
Wind
Geothermal
Biomass
Hydropower
Ocean
<1
500
600
527
>1,000
50
<250 Slide23
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
16-2 What Are the Advantages and Disadvantages of Solar Energy?Slide24
Passive solar heating systemAbsorbs and stores heat from the sun directly within a well-insulated structure
Active solar heating system
Captures energy from the sun by pumping a heat-absorbing fluid through special collectors, usually mounted on a roof or on special racks to face the sun.
We Can Heat Buildings and Water with Solar EnergySlide25
Fig. 16-14, p. 415
Trade-Offs
Passive or Active Solar Heating
Advantages
Disadvantages
Net energy is moderate (active) to high (passive)
Need access to sun 60% of time during daylight
Very low emissions of CO
2
and other air pollutants
Sun can be blocked by trees and other structures
High installation and maintenance costs for active systems
Very low land disturbance
Moderate cost (passive)
Need backup system for cloudy daysSlide26
Technologies availableOpen windows when cooler outside
Use fans
Superinsulation and high-efficiency windowsOverhangs or awnings on windowsLight-colored roofGeothermal pumps
We Can Cool Buildings NaturallySlide27
Solar thermal systems (CSP)Collect sunlight to boil water and produce steam to generate electricity
1% of world deserts could supply all the world’s electricity
Require large amounts of waterWet coolingDry cooling
Low net energy yields
We Can Concentrate Sunlight to Produce High-Temperature Heat and ElectricitySlide28
Fig. 16-15, p. 416Slide29
Fig. 16-16, p. 416
Solar Thermal Systems
High potential for growth
Low net energy and high costs
Advantages
Disadvantages
No direct emissions of CO
2
and other air pollutants
Needs backup or storage system on cloudy days
Source of new jobs
Can disrupt desert ecosystems
Trade-Offs
Lower costs with natural gas turbine backup Slide30
Photovoltaic (PV) cells, aka solar cells Convert solar energy to electric energy
Design of solar cells
Thin wafers of purified silicon (Si) or polycrystalline silicon with trace amounts of metals that allow them to conduct electricity.Sunlight hits cells and releases electrons into wires, producing electrical power
We Can Use Solar Cells to Produce ElectricitySlide31
Key problemsHigh cost of producing electricity
Need to be located in sunny desert areas
Fossil fuels used in productionSolar cells contain toxic materialsCost could drop with:Mass production and new designs
Government subsidies and tax breaks
We Can Use Solar Cells to Produce Electricity (cont’d.)Slide32
Fig. 16-18, p. 418Slide33
Fig. 16-19, p. 418Slide34
Fig. 16-21, p. 419
Solar Cells
Advantages
Disadvantages
Medium net energy yield
Need access to sun
Little or no direct emissions of CO
2
and other air pollutants
Need electricity storage system or backup
Easy to install, move around, and expand as needed
Costs high for older systems but dropping rapidly
Solar-cell power plants could disrupt desert ecosystems
Competitive cost for newer cells
Trade-Offs
Some designs have low net energy yield Slide35
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
16-4 What Are the Advantages and Disadvantages of Using Hydropower Slide36
Hydropower
Uses kinetic energy of moving
water to produce electricity.Indirect form of solar energy; depends on heat from the sun evaporating water, which is deposited as rain or snow at higher elevations where it can flow to lower elevations in rivers
World’s leading renewable energy source used to produce
electricity
We Can Produce Electricity from Falling and Flowing Water Slide37
Fig. 16-22, p. 420
Large-Scale Hydropower
Advantages
Disadvantages
High net energy yield
Large land disturbance and displacement of people
Low-cost electricity
High CH
4
emissions from rapid biomass decay in shallow tropical reservoirs
Low emissions of CO
2
and other air pollutants in temperate areas
Disrupts downstream aquatic ecosystems
Trade-Offs
Large untapped potentialSlide38
Produce electricity from flowing waterOcean tides and waves in coastal bays and estuaries
Power systems are limited
Few suitable sitesCitizen opposition High costs
Equipment damaged by storms and
saltwater corrosion
We Can Use Tides and Waves to Produce ElectricitySlide39
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
16-5 What Are the Advantages and Disadvantages of Using Wind Power?Slide40
Tall, long-blade turbines can extract more energy from the wind with less ecological footprint.
Rapidly growing power source
U.S., Europe, and ChinaFuture is offshore wind farmsWind power has potential to produce 40 times of the world’s current electricity used
Using Wind to Produce Electricity Is an Important Step toward SustainabilitySlide41
Wind is abundant, widely distributed, and inexhaustibleHigh net energy yield
Drawbacks:
Largest potential areas are usually ruralWinds can die down – need backup power source
Using Wind to Produce Electricity Is an Important Step (cont’d.)Slide42
Fig. 16-25, p. 423
Trade-Offs
Wind Power
Advantages
Disadvantages
High net energy yield
Needs backup or storage system when winds die down
Low electricity cost
Visual pollution for some people
Low-level noise bothers some people
Can kill birds if not properly designed and located
Widely available
Easy to build and expand
Little or no direct emissions of CO
2
and other air pollutantsSlide43
Biomass
Consists of p
lant materials and animal waste we can burn or turn into biofuelsWood, wood wastes, charcoal made from wood, are burned mostly for heating and cooking
Production of solid mass fuel
Plant fast-growing
trees in biomass plantations
Collect crop residues and animal manureWe Can Produce Energy by Burning Solid BiomassSlide44
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
Biomass
as an Energy SourceSlide45
Fig. 16-26, p. 424
Solid Biomass
Advantages
Disadvantages
Widely available in some areas
Contributes to deforestation
Clear-cutting can cause soil erosion, water pollution, and loss of wildlife habitat
No net CO
2
increase if harvested, burned, and replanted sustainably
Medium net energy yield
Plantations can help restore degraded lands
Trade-Offs
Increases CO
2
emissions if harvested and burned unsustainably
Can open ecosystems to invasive species
Moderate costsSlide46
We can use liquid biofuels, ethanol and biodiesel,
derived from biomass to lessen our dependence on oil-based fuels, but creating biofuel plantations can:Degrade soil and biodiversityIncrease greenhouse gas emissions
Lead to higher food prices
Biomass
as an Energy Source (cont’d.)Slide47
Ethanol
Can be made from sugarcane, corn, switchgrass, and various wastes
United States largest producerMade from corn; low net energy yieldBrazil secondSugarcane has medium net energy yield
Cellulosic
ethanol
Possible alternative to corn-based ethanolProduced from
cellulose needs more research!Case Study: Is Ethanol the Answer?Slide48
Problems with cellulosic ethanolChemical processes still being developed
Growing enough switchgrass would require too much land
Evaluating use of algae and bacteriaCase Study: Is Ethanol the Answer? (cont’d.)Slide49
BiodieselProduced from vegetable oil
European Union countries produce 95% of the world’s biodiesel
Crops require large amounts of landProduction requires fossil fuels
Case Study: Is Biodiesel the Answer?Slide50
Fig. 16-28, p. 426
Liquid Biofuels
Advantages
Disadvantages
Reduced CO
2
emissions for some crops
Fuel crops can compete with food crops for land and raise food prices
Medium net energy yield for biodiesel from oil palms
Fuel crops can be invasive species
Low net energy yield for corn ethanol and for biodiesel from soybeans
Medium net energy yield for ethanol from sugarcane
Higher CO
2
emissions from corn ethanol
Trade-OffsSlide51
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
16-7 What Are the Advantages and Disadvantages of Geothermal Energy?Slide52
With geothermal energy, heat is stored in:Soil
Underground rocks
Fluids in the earth’s mantleGeothermal heat pump systemEnergy efficient and reliableEnvironmentally clean
Cost effective to heat or cool a space
We Can Get Energy by Tapping the Earth’s
Internal HeatSlide53
Hydrothermal reservoirs Drill wells and extract various
steams and water
U.S. is the world’s largest producerGeothermal energy problemsHigh cost of tapping hydrothermal reservoirsDry- or wet-steam geothermal reservoirs could be depleted
Could create earthquakes
We Can Get Energy by Tapping the Earth’s
Internal Heat (cont’d.)Slide54
Fig. 16-30a, p. 428
Production well
Geothermal reservoir
Injection well
Heat exchanger
Steam turbine
Generator
2. Heat from underground spins a turbine to power a generator and produce electricity
1. Hot water or steam is pumped under pressure to the surface from underground
3. Steam from turbine condenses to water and is pumped back down to geothermal reservoir Slide55
Fig. 16-30b, p. 428Slide56
Fig. 16-31, p. 430
Geothermal Energy
Advantages
Disadvantages
Medium net energy yield and high efficiency at accessible sites
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
Trade-OffsSlide57
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
16-8 The Advantages and Disadvantages of Using Hydrogen as an Energy SourceSlide58
Hydrogen as a fuelEliminates most of the air pollution problems
Reduces threats of global
warmingH2 is said to be a fuel of the future and Fuel cells that combine H
2
and O
2 to produce electricity and water vapor
Will Hydrogen Save Us?Slide59
Some challenges1. Chemically
locked in water and organic compounds –
has a net negative energy yield2. Expensive fuel cells are the best way to use hydrogen
3. CO
2
levels dependent on method of hydrogen production
Will Hydrogen Save Us?Slide60
Fig. 16-32, p. 430
Electrons
Hydrogen gas (H
2
) in
Polymer electrolyte membrane
Anode
Cathode
Protons
Water
vapor (H
2
O) out
Air (O
2
) inSlide61
Fig. 16-33, p. 432
Trade-Offs
Hydrogen
Advantages
Disadvantages
Can be produced from plentiful water at some sites
Fuel cell
Negative net energy yield
CO
2
emissions
if produced from carbon-containing compounds
No CO
2
emissions if produced with use of renewables
Good substitute for oil
High costs create need for subsidies
High efficiency in fuel cells
Needs H
2
storage and distribution systemSlide62
We can make the transition to a more sustainable energy future by:
Greatly improving energy efficiency
Using a mix of renewable energy resourcesIncluding the environmental and health costs of energy resources in their market prices
16-8
How Can We Make the Transition to a More Sustainable Energy Future?Slide63
General conclusions:1. We will gradually
shift to smaller, decentralized
micropower systems.2. Combination of increased energy efficiency and regulated use of natural gas will be the best way to transition to renewable
energy.
3. Because
fossil fuels are abundant and artificially
cheap we will continue to use them in large quantities. Choosing Energy PathsSlide64
Bioenergy power plants
Smart electrical
and distribution
system
Small solar-cell
power plants
Solar-cell
rooftop
systems
Commercial
Fuel cells
Rooftop solar-
cell arrays
Residential
Small wind
turbine
Stepped Art
Industrial
Microturbines
Wind farm
Fig. 16-
34,
p.
433
© Cengage Learning 2015Slide65
Government strategies:1. Keep
the prices of selected energy resources artificially low
via subsidies to encourage their use1. Keep energy prices artificially high for selected resources
by removing subsidies to
discourage their use
3. Consumer education
Economics, Politics, Education, and Sustainable Energy ResourcesSlide66
Fig. 16-35, p. 434Slide67
We should evaluate energy resources on the basis of:Their potential supplies
Their net energy yields
Environmental and health impacts of using themThree Big IdeasSlide68
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
Three Big Ideas (cont’d.)Slide69
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
Three Big Ideas (cont’d.)Slide70
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
Tying It All Together: Wind Power and Sustainability