SUSTAINING THE
MILLER/SPOOLMAN
EARTH | G. TYLER MILLER | SCOTT E. SPOOLMAN
11e
10
Energy Efficiency and
Renewable Energy
© Cengage Learning 2015
Just as the 19th century belonged to coal
and the 20th century to oil,
the 21st century will belong to
the sun, the wind, and
energy from within the earth.
Lester R. Brown
© Cengage Learning 2015
© Cengage Learning 2015
10-1 Why Is Energy Efficiency an
Important Energy Resource?
• Why is energy efficiency an important
energy resource?
– Energy efficiency
• Each energy unit saved eliminates the need to
produce that energy and saves money
– Reducing waste is the quickest, cleanest, and
usually the cheapest way to provide more
energy, reduce pollution and environmental
degradation, slow global warming, and
increase economic and national security
© Cengage Learning 2015
We Waste Huge Amounts of Energy
• Energy is wasted by:
– Huge data centers (electronic clouds) filled
with racks of electronic servers
– Internal combustion engines
– Nuclear power plants
– Coal-fired power plants
© Cengage Learning 2015
Energy Inputs
System
Outputs
9%
7%
41%
85%
U. S.
economy
43%
8%
3%
Nonrenewable fossil fuels
Nonrenewable nuclear
Renewable (hydropower,
geothermal, wind, solar,
biomass)
Fig. 10-1
Useful energy
Petrochemicals
Unavoidable energy
loss
Energy waste
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. 10-2
We Can Save Energy and Money in
Industry and Utilities
• Cogeneration or combined heat and power
(CHP)
– Two energy forms from the same fuel source
• Replace energy-wasting electric motors
• Recycle materials
• Switch from low-efficiency incandescent
lighting to
– Higher-efficiency fluorescent and LED lighting
© Cengage Learning 2015
Case Study: Saving Energy and Money
with a Smarter Electrical Grid
• Electrical grid system: outdated and
wasteful
• Convert and expand into a smart grid
– Two-way energy and information flow
between producers and users
• Smart meters
• Smart appliances
• Remote control
• Save $100 billion/yr in the U.S.
© Cengage Learning 2015
We Can Save Energy and Money in
Transportation
• Transportation in the U.S.
– 28 percent of energy consumed
– Two-thirds of the oil consumption
• Hidden costs in gasoline: true cost $12 to
$16 per gallon
– Include subsidies and tax breaks
– Paid by the consumer but not at the gas pump
© Cengage Learning 2015
More Energy Efficient Vehicles Are Hitting
the Roads
• Super-efficient cars
– Gasoline–electric hybrid cars
– Plug-in hybrid electric vehicles
– All-electric vehicles
– Main deterrent is high cost of batteries
• Cars made of ultralight and ultrastrong
composite materials
– Significantly improves fuel efficiency
© Cengage Learning 2015
Conventional hybrid
Fuel tank
Plug-in hybrid
Fuel tank
Battery
Battery
Internal
combustion
engine
Transmission Electric motor
Stepped Art
Fig. 10-2
Internal
combustion
engine
Transmission Electric motor
We Can Design Buildings That Save
Energy and Money
• Green architecture
– Energy-efficient, money-saving designs
• Natural lighting
• Solar energy
• Wastewater recycling
• Energy-efficient appliances and lighting
– Living roofs (green roofs)
• Superinsulation
© Cengage Learning 2015
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.
Stepped Art
Fig. 10-4
Outside
Plant deciduous trees to block
summer sun and let in winter
sunlight.
Other rooms
• Use compact fluorescent
light bulbs 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.
Why Are We Still Wasting So
Much Energy?
• Energy remains artificially cheap
– Government subsidies
– Tax breaks
– Prices don’t include true costs
• Few large and long-lasting motivations
– Tax breaks
– Rebates
– Other economic incentives
© Cengage Learning 2015
We Can Use Renewable Energy to
Provide Heat and Electricity
• Renewable energy
– Solar energy: direct or indirect
– Geothermal energy
• Renewable energy more attractive if we
eliminate
– Inequitable subsidies
– Inaccurate prices
– Artificially low pricing of nonrenewable energy
© Cengage Learning 2015
10-2 What Are the Advantages and
Disadvantages of Using Solar Energy?
• We can heat buildings and water with
solar energy
– Passive solar heating systems
– Active solar heating systems
© Cengage Learning 2015
Summer
sun
White or light-colored
roofs reduce overheating
Vent allows
hot air to
escape in
summer
Heavy
insulation
Winter
sun
Superwindow
Superwindow
Stone floor and wall for heat storage
Fig. 10-5
PASSIVE
Fig. 10-5 (cont’d.)
Fig. 16-12b, p. 414
We Can Concentrate Sunlight to Produce
High-Temperature Heat and Electricity
• Types of solar thermal systems
– Central receiver system
• Power tower (central receiver)
• Heliostats
– System with curved solar collectors
• Collects and focuses sunlight on oil-filled pipes
• Produce steam for driving electricity-generating
turbines
– Solar cookers to cook food and sterilize water
© Cengage Learning 2015
We Can Use Sunlight to Produce
Electricity
• Photovoltaic (PV) cells (solar cells)
– Convert solar energy to electric energy
• Design of solar cells
– Sunlight hits cells and releases electrons
• Benefits of using solar cells
• Solar-cell power plants around the world
• World’s fastest growing way to produce
electricity
© Cengage Learning 2015
Trade-Offs
Solar Cells
Advantages
Disadvantages
Medium net
energy yield
Need access to sun
Little or no direct
emissions of CO2
and other air
pollutants
Easy to install,
move around,
and expand as
needed
Competitive cost
for newer cells
Fig. 10-9
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
10-3 What Are the Advantages and
Disadvantages of Using Hydropower?
• We can produce electricity from falling and
flowing water
– Hydropower
• Indirect form of solar energy
• Uses kinetic energy of moving water
• Most common approach involves a high dam
across a large river
– Advantages and disadvantages
– Micro-hydropower generators
© Cengage Learning 2015
Hydroelectric
Power Plant
Trade-Offs
Large-Scale Hydropower
Advantages
Disadvantages
High net energy
yield
Large land
disturbance and
displacement of
people
Large untapped
potential
Low-cost
electricity
Low emissions of
CO2 and other air
pollutants in
temperate areas
Fig. 10-10
High CH4 emissions
from rapid biomass
decay in shallow
tropical reservoirs
Disrupts downstream
aquatic ecosystems
10-4 What Are the Advantages and
Disadvantages of Using Wind Power?
• Using wind to produce electricity is an
important step toward sustainability
– Wind: indirect form of solar energy
• Captured by turbines
• Converted into electrical energy
– Second fastest-growing energy source
– Wind farms: on land and offshore
– Advantages and disadvantages
© Cengage Learning 2015
Wind
Energy
Potential
Trade-Offs
Wind Power
Advantages
Disadvantages
High net energy
yield
Needs backup or
storage system when
winds die down
Widely available
Low electricity
cost
Little or no direct
emissions of CO2
and other air
pollutants
Easy to build
and expand
Fig. 10-12
Visual pollution for
some people
Low-level noise
bothers some people
Can kill birds if not
properly designed
and located
10-5 Advantages and Disadvantages of
Using Biomass as an Energy Source
• We can produce energy by burning solid
biomass
– Biomass: plant materials and animal wastes
• 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
© Cengage Learning 2015
Trade-Offs
Solid Biomass
Advantages
Disadvantages
Widely available
in some areas
Contributes to
deforestation
Moderate costs
Medium net
energy yield
Clear-cutting can
cause soil erosion,
water pollution, and
loss of wildlife habitat
No net CO2
increase if
harvested,
burned, and
replanted
sustainably
Can open
ecosystems to
invasive species
Plantations can
help restore
degraded lands
Fig. 10-13
Increases CO2
emissions if harvested
and burned
unsustainably
We Can Convert Plants and Plant Wastes
to Liquid Biofuels
• Liquid biofuels
– Examples: biodiesel and ethanol
• Biggest producers of biofuel
– Brazil
– United States
– European Union
– China
• Advantages and potential problems
© Cengage Learning 2015
Case Study: Is Ethanol the Answer?
• Ethanol from plants and from agricultural,
forestry, and municipal wastes
• Brazil produces ethanol from sugarcane
– Environmental consequences
• United States: most ethanol from corn
• Cellulosic ethanol
• Debates over greenhouse gas emissions
© Cengage Learning 2015
Trade-Offs
Liquid Biofuels
Advantages
Disadvantages
Reduced CO2
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
Medium net
energy yield for
ethanol from
sugarcane
Fig. 10-14
Low net energy yield
for corn ethanol and
for biodiesel from
soybeans
Higher CO2
emissions from
corn ethanol
Waste
(Garbage)
34
• Waste is a major source of biomass and other
burnable materials produced by society.
• The burning of solid waste only makes
economic sense when the cost of waste
disposal is taken into account.
• Using municipal waste as a source of energy:
– Reduces landfill volume.
– Requires large volume and dependable supply,
and must be sorted.
– Produces air pollution, including pollutants not
found in other forms of biomass.
10-6 What Are the Advantages and
Disadvantages of Geothermal Energy?
• 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
© Cengage Learning 2015
Trade-Offs
Geothermal Energy
Fig. 10-15
Advantages
Disadvantages
Medium net energy
yield and high
efficiency at
accessible sites
High cost 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
10-7 The Advantages and Disadvantages
of Using Hydrogen as an Energy Source
• Will hydrogen save us?
– Hydrogen as a fuel
• Eliminate most of the air pollution problems
• Reduce threats of global warming
– Challenges
• Negative net energy yield
• Expensive fuel cells are the best way to use
hydrogen
• Air pollution and CO2 levels dependent on
hydrogen production method
© Cengage Learning 2015
Trade-Offs
Hydrogen
Fig. 10-16
Advantages
Disadvantages
Can be produced
Fuel
from plentiful
cell
water at some sites
Negative net
energy yield
No CO2 emissions
if produced with
use of renewables
CO2 emissions
if produced from
carbon-containing
compounds
Good substitute
for oil
High costs create
need for subsidies
High efficiency in
fuel cells
Needs H2 storage
and distribution
system
10-8 How Can We Make the Transition to
a More Sustainable Energy Future?
• Choosing energy paths
– How will energy policies be created?
– General conclusions
• Gradual shift to smaller, decentralized micropower
systems
• Transition to a diverse mix of locally available
renewable energy resources
• Fossil fuels will still be used in large amounts
© Cengage Learning 2015
Bioenergy power plants
Wind farm
Small solar-cell
power plants
Fuel cells
Solar-cell
rooftop
systems
Rooftop solarcell arrays
Smart electrical
and distribution
system
Commercial
Residential
Small
wind
turbine
Industrial
Stepped Art
Fig. 10-17
Microturbines
Solutions
Making the Transition to a More Sustainable Energy Future
Improve Energy Efficiency
Increase fuel-efficiency
standards for vehicles,
buildings, and appliances
Provide large tax credits or
feebates for buying efficient
cars, houses, and appliances
Reward utilities for reducing
demand for electricity
Greatly increase energy
efficiency research and
development
Fig. 10-18
More Renewable Energy
Greatly increase use of renewable energy
Provide large subsidies and tax credits for use of
renewable energy
Greatly increase renewable energy research and
development
Reduce Pollution and Health Risk
Phase out coal subsidies and tax breaks
Levy taxes on coal and oil use
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
– Emphasize consumer education
© Cengage Learning 2015
Energy Conservation
• There is typically a relationship between the
cost of an item and its energy efficiency.
– Often, poorly designed, energy-inefficient
buildings and machines can be produced
inexpensively.
• The short-term cost (purchase price) is low, but the
long-term cost for upkeep and energy utilization is high.
– Typically, the cost of more efficient buildings or
machines is higher, but the difference in initial
price is made up by savings in energy cost over
several years.
• This is known as the payback period.
Fig. 10-19
Energy Conservation
The Economics and Politics of
Energy Use
• A direct link exists between economic
growth and the availability of inexpensive
energy.
– Most industrial societies want to ensure a
continuous supply of affordable energy.
– The higher the price of energy, the more
expensive goods and services become.
– Subsidies help keep energy costs down.
46
Fuel Economy and Government
Policy
• Automobile fuel efficiency is one
area in which government policy
has had significant impact.
• Most of the differences in gasoline
prices among countries are a result
of taxes and reflect differences in
government policy toward motor
vehicle transportation.
Do cars in the United States
have high or low gas
mileage levels compared to
other countries?
47
49
Fuel Economy and Government Policy
• Governments often charge
road users to help build and
repair roads by taxing fuel.
– Many European countries
raise more money from fuel
taxes than they spend on
building and repairing
roads.
– U.S. only raises 50% of
monies needed for roads
from fuel taxes.
– Low fuel costs in the U.S.
encourage more travel,
which increases road repair
costs.