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TRANSCRIPT
17TH MILLER/SPOOLMAN
LIVING IN THE ENVIRONMENT
Chapter 16
Energy Efficiency and Renewable Energy
Core Case Study: Amory Lovins and The Rocky Mountain Institute (1)
• Amory Lovins, energy analyst
• Rocky Mountain Institute • Nonprofit and nonpartisan
• Research and consulting on energy, energy efficiency, and renewable energy
• Consults with 80 major corporations and 50 foreign countries
Core Case Study: Amory Lovins and The Rocky Mountain Institute (2)
• Location: Snowmass, CO (U.S.)
• No conventional heating system
• Heating bills: <$50/year
• How is this possible?
Sustainable Energy: Rocky Mountain Institute in Colorado, U.S.
Fig. 16-1, p. 397
16-1 Why Is Energy Efficiency an Important Energy Resource?
• Concept 16-1 Improving energy efficiency can save the world at least a third of the energy it uses, and it can save the United States up to 43% of the energy it uses.
We Waste Huge Amounts of Energy (1) • Energy efficiency
• Advantages of reducing energy waste: • Quick and clean
• Usually the cheapest to provide more energy
• Reduce pollution and degradation
• Slow global warming
• Increase economic and national security
We Waste Huge Amounts of Energy (2) • Four widely used devices that waste energy
1. Incandescent light bulb
2. Motor vehicle with internal combustion engine
3. Nuclear power plant
4. Coal-fired power plant
Flow of Commercial Energy through the U.S. Economy
Fig. 16-2, p. 399
Fig. 16-2, p. 399
Energy Inputs System Outputs
9%
7%
41% 85%
U. S. economy
43%
8%
4%
Nonrenewable fossil fuels Useful energy
Hydropower, geothermal, wind, solar Unnecessary energy
waste
3%
Petrochemicals
Unavoidable energy waste
Nonrenewable nuclear
Biomass
Advantages of Reducing Energy Waste
Fig. 16-3, p. 399
Fig. 16-3, p. 399
Solutions
Reducing Energy Waste
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
16-2 How Can We Cut Energy Waste?
• Concept 16-2 We have a variety of technologies for sharply increasing the energy efficiency of industrial operations, motor vehicles, and buildings.
We Can Save Energy and Money in Industry and Utilities (1)
• Cogeneration or combined heat and power (CHP)
• Two forms of energy from same fuel source
• Replace energy-wasting electric motors
• Recycling materials
• Switch from low-efficiency incandescent lighting to higher-efficiency fluorescent and LED lighting
LEDs
Fig. 16-4, p. 401
We Can Save Energy and Money in Industry and Utilities (2)
• Electrical grid system: outdated and wasteful
• Utility companies switching from promote use of energy to promoting energy efficiency
• Spurred by state utility commissions
Case Study: Saving Energy and Money with a Smarter Electrical Grid
• Smart grid
• Ultra-high-voltage
• Super-efficient transmission lines
• Digitally controlled
• Responds to local changes in demand and supply
• Two-way flow of energy and information
• Smart meters show consumers how much energy each appliance uses
• U.S cost -- $200-$800 billion; save $100 billion/year
Proposed U.S. Smart Grid
Figure 20, Supplement 8
We Can Save Energy and Money in Transportation
• Corporate average fuel standards (CAFE) standards
• Fuel economy standards lower in the U.S. countries
• Fuel-efficient cars are on the market
• Hidden prices in gasoline: $12/gallon
• Car manufacturers and oil companies lobby to prevent laws to raise fuel taxes
• Should there be a feebate?
Average Fuel Economy of New Vehicles Sold in the U.S. and Other Countries
Fig. 16-5, p. 402
Fig. 16-5a, p. 402
30
Cars
25
20 Trucks
15
Ave
rage
fu
el e
con
om
y (m
iles
pe
r ga
llon
)
10
1975 1980 1985 1990 1995 2000 2005 2010
Year
Fig. 16-5b, p. 402
50
45 Europe
40 Japan
35 China
Mile
s p
er
gallo
n (
mp
g)
(co
nve
rte
d t
o U
.S. t
est
eq
uiv
alen
ts)
30 Canada
25
20
United States
2002 2004 2006 2008
Year
Stepped Art
25 Cars
20 Cars, trucks, and SUVs
Trucks and SUVs 15
Ave
rag
e f
ue
l e
co
no
my (
mil
es
pe
r g
all
on
)
10
1975 1980 1985 1990 1995 2000 2005
Year
50
45 Europe
40 Japan
35 China
Mile
s p
er
ga
llo
n (
mp
g)
(co
nve
rte
d t
o U
.S. te
st
eq
uiv
ale
nts
)
30 Canada
25 United
States 20
2002 2004 2006 2008
Year
Fig. 16-5, p. 402
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
Solutions: A Hybrid-Gasoline-Electric Engine Car and a Plug-in Hybrid Car
Fig. 16-6, p. 403
Fig. 16-6, p. 403
Conventional hybrid Fuel tank
Battery
Internal combustion engine
Transmission Electric motor
Fig. 16-6, p. 403
Plug-in hybrid Fuel tank
Battery
Internal combustion engine
Transmission Electric motor
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. 403
Light-Weight Carbon Composite Concept Car
Fig. 16-7, p. 405
Science Focus: The Search for Better Batteries
• Current obstacles • Storage capacity
• Overheating
• Flammability
• Cost
• In the future
• Lithium-ion battery
• Viral battery
• Ultracapacitor
We Can Design Buildings That Save Energy and Money
• Green architecture
• Living or green roofs
• Superinsulation
• U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED)
A Green Roof in Chicago
Fig. 16-8, p. 405
We Can Save Money and Energy in Existing Buildings (1)
• Conduct an energy survey
• Insulate and plug leaks
• Use energy-efficient windows
• Stop other heating and cooling losses
• Heat houses more efficiently
We Can Save Money and Energy in Existing Buildings (2)
• Heat water more efficiently
• Use energy-efficient appliances
• Use energy-efficient lighting
A Thermogram Shows Heat Loss
Fig. 16-9, p. 406
Individuals Matter: Ways in Which You Can Save Money Where You Live
Fig. 16-10, p. 407
Fig. 16-10, p. 407
Attic Outside • Hang reflective foil near roof to reflect heat.
Plant deciduous trees to block summer sun and let in winter sunlight.
• 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. Other rooms
• Use compact fluorescent lightbulbs or LEDs and avoid using incandescent bulbs.
Kitchen • Use microwave rather than stove or oven as much as possible.
• Turn off lights, computers, TV, and other electronic devices when they are not in use.
• Run only full loads in dishwasher and use low- or no-heat drying. • Use high efficiency
windows; use insulating window covers and close them at night and on sunny, hot days.
• Clean refrigerator coils regularly.
• Set thermostat as low as you can in winter and as high as you can in summer.
Basement or utility room • Use front-loading clothes washer. If possible run only full loads with warm or cold water.
• Weather-strip and caulk doors, windows, light fixtures, and wall sockets.
• If possible, hang clothes on racks for drying.
• Run only full loads in clothes dryer and use lower heat setting. • Keep heating and cooling vents free of obstructions. • Set water heater at 140°F if dishwasher is used and 120°F or lower if
no dishwasher is used. • Keep fireplace damper closed when not in use. • Use water heater thermal blanket.
• Insulate exposed hot water pipes. • Use fans instead of, or along with, air conditioning. • 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.
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. 407
Why Are We Still Wasting So Much Energy?
• Energy remains artificially cheap • Government subsidies
• Tax breaks
• Prices don’t include true cost
• Few large and long-lasting incentives • Tax breaks
• Rebates
• Low-interest loans
We Can Use Renewable Energy to Provide Heat and Electricity
• Renewable energy • Solar energy: direct or indirect
• Geothermal energy
• Benefits of shifting toward renewable energy
• Renewable energy cheaper if we eliminate • Inequitable subsidies
• Inaccurate prices
• Artificially low pricing of nonrenewable energy
16-3 What Are the Advantages and Disadvantages of Solar Energy?
• Concept 16-3 Passive and active solar heating systems can heat water and buildings effectively, and the costs of using direct sunlight to produce high-temperature heat and electricity are coming down.
We Can Heat Buildings and Water with Solar Energy
• Passive solar heating system
• Active solar heating system
Solutions: Passive and Active Solar Heating for a Home
Fig. 16-11, p. 409
Fig. 16-11a, p. 409
White or light-colored roofs reduce overheating Vent allows hot
air to escape in summer Summer
sun Heavy insulation
Winter sun
Superwindow
Super- window
Stone floor and wall for heat storage
PASSIVE
Fig. 16-11b, p. 409
Solar collector White or light-colored roofs reduce overheating
Heat to house (radiators or forced air duct)
Pump
Heavy insulation Super- window
Hot water tank
Heat exchanger
ACTIVE
Passive Solar Home in Colorado
Fig. 16-12, p. 410
Rooftop Solar Hot Water on Apartment Buildings in Kunming, China
Fig. 16-13, p. 410
Trade-Offs: Passive or Active Solar Heating
Fig. 16-14, p. 411
Fig. 16-14, p. 411
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 CO2 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 days
World Availability of Direct Solar Energy
Figure 22, Supplement 8
U.S. Availability of Direct Solar Energy
Figure 23, Supplement 8
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
We Can Use Sunlight to Produce High-Temperature Heat and Electricity
• Solar thermal systems
• Central receiver system
• Collect sunlight to boil water, generate electricity
• 1% of world deserts could supply all the world’s electricity
• Require large amounts of water – could limit
• Wet cooling
• Dry cooling
• Low net energy yields
Solar Thermal Power in California Desert
Fig. 16-15, p. 411
Trade-Offs: Solar Energy for High Temperature Heat and Electricity
Fig. 16-16, p. 412
Fig. 16-16, p. 412
Solar Energy for High-Temperature Heat and Electricity
Moderate environmental impact
Low net energy and high costs
Advantages Disadvantages
No direct emissions of CO2 and other air pollutants
Needs backup or storage system on cloudy days
Lower costs with natural gas turbine backup
High water use for cooling
Trade-Offs
Solutions: Solar Cooker in India
Fig. 16-17, p. 412
We Can Use Sunlight to Produce Electricity (1)
• Photovoltaic (PV) cells (solar cells)
• Convert solar energy to electric energy
• Design of solar cells
• Sunlight hits cells and releases electrons into wires
• Benefits of using solar cells
• Solar-cell power plants around the world
Solutions: Solar Cells on Rooftop and for Many Purposes
Fig. 16-18, p. 413
Solar Cell Array in Niger, West Africa
Fig. 16-19, p. 413
Solar-Cell Power Plant in Arizona
Fig. 16-20, p. 414
We Can Use Sunlight to Produce Electricity (2)
• 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
• Will the cost drop with
• Mass production
• New designs
• Government subsidies and tax breaks
We Can Use Sunlight to Produce Electricity (3)
• 2040: could solar cells produce 16%?
• Nanosolar: California (U.S.)
• Germany: huge investment in solar cell technology
• General Electric: entered the solar cell market
Global Production of Solar Electricity
Figure 11, Supplement 9
Trade-Offs: Solar Cells
Fig. 16-21, p. 414
Fig. 16-21, p. 414
Solar Cells
Advantages Disadvantages
Moderate net energy yield
Need access to sun
Little or no direct emissions of CO2 and other air pollutants
Need electricity storage system or backup
Easy to install, move around, and expand as needed
High costs for older systems but decreasing rapidly
Solar-cell power plants could disrupt desert ecosystems
Competitive cost for newer cells
Trade-Offs
16-4 What Are the Advantages and Disadvantages of Using Hydropower
• Concept 16-4 We can use water flowing over dams, tidal flows, and ocean waves to generate electricity, but environmental concerns and limited availability of suitable sites may limit the use of these energy resources.
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
• Advantages and disadvantages
• Micro-hydropower generators
Tradeoffs: Dams and Reservoirs
Fig. 13-13, p. 328
Fig. 13-13a, p. 328
Provides irrigation water above and below dam
Flooded land destroys forests or cropland and displaces people
Large losses of water through evaporation
Provides water for drinking
Deprives downstream cropland and estuaries of nutrient-rich silt
Reservoir useful for recreation and fishing
Risk of failure and devastating downstream flooding
Can produce cheap electricity (hydropower)
Reduces down-stream flooding of cities and farms Disrupts
migration and spawning of some fish
Fig. 13-13b, p. 328
Powerlines
Reservoir
Dam
Intake Powerhouse
Turbine
Trade-Offs: Large-Scale Hydropower, Advantages and Disadvantages
Fig. 16-22, p. 415
Fig. 16-22, p. 415
Large-Scale Hydropower
Advantages Disadvantages
Moderate to high net energy
Large land disturbance and displacement of people
Low-cost electricity High CH4 emissions from rapid biomass decay in shallow tropical reservoirs
Low emissions of CO2 and other air pollutants in temperate areas Disrupts downstream
aquatic ecosystems
Trade-Offs
Large untapped potential
Tides and Waves Can Be Used to Produce Electricity
• Produce electricity from flowing water • Ocean tides and waves
• So far, power systems are limited
• Disadvantages • Few suitable sites
• High costs
• Equipment damaged by storms and corrosion
16-5 What Are the Advantages and Disadvantages of Using Wind Power? • Concept 16-5 When we include the environmental
costs of using energy resources in the market prices of energy, wind power is the least expensive and least polluting way to produce electricity.
Using Wind to Produce Electricity Is an Important Step toward Sustainability (1)
• Wind: indirect form of solar energy
• Captured by turbines
• Converted into electrical energy
• Second fastest-growing source of energy
• What is the global potential for wind energy?
• Wind farms: on land and offshore
World Electricity from Wind Energy
Figure 12, Supplement 9
Solutions: Wind Turbine and Wind Farms on Land and Offshore
Fig. 16-23, p. 417
Fig. 16-23a, p. 417
Gearbox
Electrical generator
Power cable
Wind turbine
Fig. 16-23b, p. 417 Wind farm
Fig. 16-23c, p. 417 Wind farm (offshore)
Wind Turbine
Fig. 16-24, p. 417
Using Wind to Produce Electricity Is an Important Step toward Sustainability (2)
• Countries with the highest total installed wind power capacity
• Germany
• United States
• Spain
• India
• Denmark
• Installation is increasing in several other countries
Using Wind to Produce Electricity Is an Important Step toward Sustainability (3)
• Advantages of wind energy
• Drawbacks • Windy areas may be sparsely populated – need to
develop grid system to transfer electricity
• Winds die down; need back-up energy
• Storage of wind energy
• Kills migratory birds
• “Not in my backyard”
Trade-Offs: Wind Power
Fig. 16-25, p. 418
Fig. 16-25, p. 418
Trade-Offs
Wind Power
Advantages Disadvantages
Moderate to 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 CO2 and other air pollutants
Case Study: The Astounding Potential of Wind Power in the United States
• “Saudi Arabia of wind power”
• North Dakota
• South Dakota
• Kansas
• Texas
• How much electricity is possible with wind farms in those states?
• Could create up to 500,000 jobs
United States Wind Power Potential
Figure 24, Supplement 8
16-6 Advantages and Disadvantages of Using Biomass as an Energy Source
• Concept 16-6A 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, and creating biomass plantations can degrade soil biodiversity.
• Concept 16-6B We can use liquid biofuels derived from biomass in place of gasoline and diesel fuels, but creating biofuel plantations can degrade soil and biodiversity and increase food prices and greenhouse gas emissions.
We Can Get 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
• Advantages and disadvantages
Trade-Offs: Solid Biomass
Fig. 16-26, p. 420
Fig. 16-26, p. 420
Solid Biomass
Advantages Disadvantages
Widely available in some areas
Moderate to high environmental impact
Increases CO2 emissions if harvested and burned unsustainably
No net CO2 increase if harvested, burned, and replanted sustainably
Moderate costs
Plantations can help restore degraded lands
Trade-Offs
Often burned in inefficient and polluting open fires and stoves
Clear cutting can cause soil erosion, water pollution, and loss of wildlife habitat
We Can Convert Plants and Plant Wastes to Liquid Biofuels (1)
• Liquid biofuels
• Biodiesel
• Ethanol
• Biggest producers of biofuel
• The United States
• Brazil
• The European Union
• China
We Can Convert Plants and Plant Wastes to Liquid Biofuels (2)
• Major advantages over gasoline and diesel fuel produced from oil
1. Biofuel crops can be grown almost anywhere
2. No net increase in CO2 emissions if managed properly
3. Available now
We Can Convert Plants and Plant Wastes to Liquid Biofuels (3)
• Studies warn of problems:
• Decrease biodiversity
• Increase soil degrading, erosion, and nutrient leaching
• Push farmers off their land
• Raise food prices
• Reduce water supplies, especially for corn and soy
Case Study: Is Biodiesel the Answer?
• Biodiesel production from vegetable oil from various sources
• 95% produced by the European Union
• Subsidies promote rapid growth in United States
• Advantages and disadvantages
Trade-Offs: Biodiesel
Fig. 16-27, p. 421
Fig. 16-27, p. 421
Biodiesel
Advantages Disadvantages
Reduced CO and CO2 emissions
Increased NOx emissions and smog
High net energy yield for oil palm crops
Low net energy yield for soybean crops
Competes with food for cropland
Reduced hydrocarbon emissions
Clearing natural areas for plantations reduces biodiversity and increases atmospheric CO2 levels Better mileage (up
to 40%)
Trade-Offs
Case Study: Is Ethanol the Answer? (1)
• Ethanol from plants and plant wastes
• Brazil produces ethanol from sugarcane
• Environmental consequences
• United States: ethanol from corn
• Low net energy yield
• Reduce the need for oil imports?
• Harm food supply
• Air pollution and climate change?
Case Study: Is Ethanol the Answer? (2)
• Cellulosic ethanol: alternative to corn ethanol
• Switchgrass
• Crop residues
• Municipal wastes
• Advantages and disadvantages
World Ethanol Production
Figure 13, Supplement 9
Bagasse is Sugarcane Residue
Fig. 16-28, p. 421
Natural Capital: Rapidly Growing Switchgrass
Fig. 16-29, p. 423
Trade-Offs: Ethanol Fuel
Fig. 16-30, p. 423
Fig. 16-30, p. 423
Ethanol Fuel
Advantages Disadvantages
Some reduction in CO2 emissions (sugarcane bagasse)
Low net energy yield (corn) and higher cost
Higher CO2 emissions (corn)
High net energy yield (bagasse and switchgrass)
Corn ethanol competes with food crops and may raise food prices
Potentially renewable
Trade-Offs
Case Study: Getting Gasoline and Diesel Fuel from Algae and Bacteria (1)
• Algae remove CO2 and convert it to oil
• Not compete for cropland = not affect food prices
• Wastewater/sewage treatment plants
• Could transfer CO2 from power plants
• Algae challenges
1.Need to lower costs
2.Open ponds vs. bioreactors
3.Affordable ways of extracting oil
4.Scaling to large production
Case Study: Getting Gasoline and Diesel Fuel from Algae and Bacteria (2)
• Bacteria: synthetic biology
• Convert sugarcane juice to biodiesel
• Need large regions growing sugarcane
• Producing fuels from algae and bacteria can be done almost anywhere
16-7 What Are the Advantages and Disadvantages of Geothermal Energy? • Concept 16-7 Geothermal energy has great potential
for supplying many areas with heat and electricity, and it has a generally low environmental impact, but sites where it can be used economically are limited.
Getting Energy from the Earth’s Internal Heat (1)
• Geothermal energy: heat 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
Natural Capital: A Geothermal Heat Pump System Can Heat or Cool a House
Fig. 16-31, p. 425
Fig. 16-31a, p. 425
Basement pump
Geothermal heating
Fig. 16-31b, p. 425
Geothermal cooling
Getting Energy from the Earth’s Internal Heat (2)
• Hydrothermal reservoirs • U.S. is the world’s largest producer
• Hot, dry rock
• Geothermal energy problems
• High cost of tapping hydrothermal reservoirs
• Dry- or wet-steam geothermal reservoirs could be depleted
• Could create earthquakes
Geothermal Sites in the United States
Figure 26, Supplement 8
Geothermal Sites Worldwide
Figure 25, Supplement 8
Geothermal Power Plant in Iceland
Fig. 16-32, p. 425
Trade Offs: Geothermal Energy
Fig. 16-33, p. 426
Fig. 16-33, p. 426
Geothermal Energy
Advantages Disadvantages
Moderate net energy and high efficiency at accessible sites
High cost and low efficiency except at concentrated and accessible sites
Lower CO2 emissions than fossil fuels Scarcity of suitable
sites
Low cost at favorable sites
Noise and some CO2 emissions
Trade-Offs
16-8 The Advantages and Disadvantages of Using Hydrogen as an Energy Source
• Concept 16-8 Hydrogen fuel holds great promise for powering cars and generating electricity, but for it to be environmentally beneficial, we would have to produce it without the use of fossil fuels.
Will Hydrogen Save Us? (1)
• Hydrogen as a fuel • Eliminate most of the air pollution problems
• Reduce threats of global warming
• Some challenges • Chemically locked in water and organic compounds = net
negative energy yield
• Expensive fuel cells are the best way to use hydrogen
• CO2 levels dependent on method of hydrogen production
Will Hydrogen Save Us? (2)
• Net negative energy yield
• Production and storage of H2
• Hydrogen-powered vehicles: prototypes available
• Can we produce hydrogen on demand?
• Larger fuel cells – fuel-cell stacks
A Fuel Cell Separates the Hydrogen Atoms’ Electrons from Their Protons
Fig. 16-34, p. 427
Fig. 16-34a, p. 427
Electrons
Hydrogen gas (H2) in Polymer electrolyte
membrane
Anode
Cathode
Protons
Water vapor (H2O) out Air (O2) in
Trade-Offs: Hydrogen, Advantages and Disadvantages
Fig. 16-35, p. 428
Fig. 16-35, p. 428
Trade-Offs
Hydrogen
Advantages Disadvantages
Can be produced from plentiful water at some sites
Fuel cell Negative net energy yield
CO2 emissions if produced from carbon-containing compounds
No direct CO2 emissions if produced from water
Good substitute for oil
High costs require subsidies
High efficiency (45–65%) in fuel cells
Needs H2 storage and distribution system
Science Focus: The Quest to Make Hydrogen Workable
• Bacteria and algae can produce hydrogen through biodegrading organic material
• Use electricity from renewable energy sources to produce hydrogen
• Storage options for hydrogen
16-9 How Can We Make the Transition to a More Sustainable Energy Future?
• Concept 16-9 We can make the transition to a more sustainable energy future if we greatly improve energy efficiency, use a mix of renewable energy resources, and include environmental costs in the market prices of all energy resources.
Choosing Energy Paths (1)
• How will energy policies be created?
• Hard energy path
• Soft energy path
Choosing Energy Paths (2)
• General conclusions • Gradual shift to smaller, decentralized micropower
systems
• Transition to a diverse mix of locally available renewable energy resources
• Improved energy efficiency
• Fossil fuels will still be used in large amounts • Natural gas is the best choice
Solutions: Decentralized Power System
Fig. 16-36, p. 430
Fig. 16-36, p. 430
Small solar-cell power plants Bioenergy power plants Wind farm
Fuel cells
Rooftop solar- cell arrays
Solar-cell rooftop systems
Smart electrical and distribution system
Commercial
Small wind turbine Residential
Industrial Microturbines
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. 16-36, p. 430
Solutions: Making the Transition to a More Sustainable Energy Future
Fig. 16-37, p. 431
Fig. 16-37, p. 431
Solutions
Making the Transition to a More Sustainable Energy Future
Improve Energy Efficiency More Renewable Energy Increase fuel-efficiency standards for vehicles, buildings, and appliances
Greatly increase use of renewable energy
Provide large subsidies and tax credits for use of renewable energy
Provide large tax credits or feebates for buying efficient cars, houses, and appliances
Greatly increase renewable energy research and development
Reduce Pollution and Health Risk
Reward utilities for reducing demand for electricity
Phase out coal subsidies and tax breaks
Levy taxes on coal and oil use Greatly increase energy efficiency research and development Phase out nuclear power subsidies, tax breaks,
and loan guarantees
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
What Can you Do? Shifting to More Sustainable Energy Use
Fig. 16-38, p. 432
Three Big Ideas
1. We should evaluate energy resources on the basis of their potential supplies, how much net useful energy they provide, and the environmental impacts of using them.
2. Using a mix of renewable energy sources—especially solar, wind, flowing water, sustainable biofuels, and geothermal energy—can drastically reduce pollution, greenhouse gas emissions, and biodiversity losses.
Three Big Ideas
3. Making the transition to a more sustainable energy future will require sharply reducing energy waste, using a mix of environmentally friendly renewable energy resources, and including the harmful environmental costs of energy resources in their market prices.