MILLER/SPOOLMAN
LIVING IN THE ENVIRONMENT
Chapter 16
Energy Efficiency and
Renewable Energy
17TH
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
Powerlines
Reservoir
Dam
Intake
Powerhouse
Turbine
Fig. 13-13b, p. 328
Trade-Offs: Large-Scale Hydropower,
Advantages and Disadvantages
Fig. 16-22, p. 415
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
Gearbox
Electrical generator
Power cable
Wind turbine
Fig. 16-23a, p. 417
Wind farm
Fig. 16-23b, p. 417
Wind farm (offshore)
Fig. 16-23c, p. 417
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
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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
Case Study: The Astounding Potential of
Wind Power in the United States
• “Saudi Arabia of wind power”
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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
We Can Convert Plants and Plant Wastes
to Liquid Biofuels (1)
• Liquid biofuels
• Biodiesel
• Ethanol
• Biggest producers of biofuel
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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:
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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
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
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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
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
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
Snedeker has been there!!!
Fig. 16-32, p. 425
Trade Offs: Geothermal Energy
Fig. 16-33, p. 426
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
Trade-Offs: Hydrogen, Advantages and
Disadvantages
Fig. 16-35, p. 428
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
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How will energy policies be created?
Hard energy path
Soft energy path
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
Solutions: Making the Transition to a More
Sustainable Energy Future
Fig. 16-37, p. 431
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.