“The use of solar energy has not been opened up because the oil industry does not own the sun.”
- Ralph Nader
1
 Nonrenewable energy,
including fossil fuels
and nuclear power,
make up the vast
majority of the U.S.
energy portfolio.
 In the long-term, there
are two major issues
with this reliance on
nonrenewable energy:
 Dwindling supplies.
 Environmental
pollution.
2
 Nonrenewable resources, by definition, are finite and
will eventually be used up.
 Most of the easily recoverable sources of coal, oil, and
natural gas have already been tapped.
 As supplies of these resources tighten, or they become
more expensive to extract, price will increase.
3
 Deep-ocean drilling of oil and hydraulic fracturing of
natural gas are examples of resource extraction that
would not have been economically viable in the past.
4
 The extraction, transport, and burning of fossil fuels is
also a highly polluting process.
5
 Fossil fuels have a
lot of modern
applications.
 Electricity
 Fuel for
transportation
 Heat
 The strategies for
replacing them is
going to vary for
each.
6
 Electricity works by passing electrons from a power
source through a series of wires, called a circuit.
 Within the circuit there are devices that use the energy
released by the electrons to do work (as light, heat, etc)
7
 Electric power is measured in watts, the rate at which
electrons moving through a circuit are doing work.
 A standard incandescent
light bulb consumes 60W
of power.
 A medium-sized car will
consume about 100,000W.
8
 Electricity consumption is measured in kilowatt-hours.
 This includes both power and running-time.
 The charge per kilowatt-hour in this bill is 10.7 cents.
9
 At the rate shown in this bill, running a 60-watt light
bulb for an hour would cost…
60watts x 1 kilowatt/ 1000 watts = 0.06 kilowatts
0.06 kilowatt-hours x $0.107/kwh = $0.00642 or 0.662 cents.
10
 The greatest renewable source of electricity production
currently in use is hydroelectricity.
11
 Hydroelectric power plants use running water to spin a
turbine and generate electricity.
 Hydroelectricity is very economical, with costs per
kilowatt-hour similar to coal.
 No pollution is produced.
12
 The construction of the dam has major ecological impacts.
 Regular flooding downstream stops, preventing deposition of
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silt and nutrients.
The reservoir can experience sedimentation, where particles of
soil in the river settle to the bottom of the reservoir.
The ecosystem immediately behind the dam becomes flooded.
River water, when stopped, warms faster and begins to
evaporate.
Fish and other organisms can no longer move upstream.
14
 Any cities or villages in the area of the reservoir will have
to be abandoned.
The Three Gorges Dam in China, completed in 2008,
displaced 1.13 million people from the Yangtze River region.
15
 Another issue with dams is that they produce a constant,
steady stream of electricity that cannot be easily adjusted
to meet demand.
 Some dams have pumped storage, where water will be sent
and stored during low-demand times, then returned back
through the dam’s turbines when demand is higher.
Kinzua Dam
and Seneca
pumped
storage
generating
station,
Mead, PA
16
 Wind energy is similar to hydroelectricity, except that
moving air provides the force to spin the generator.
17
 Wind turbines are able to orient themselves to face the
oncoming wind.
 As the air passes through, the blades rotate.
 These are attached to a shaft, which connects to the
turbine.
18
 A single wind turbine can generate 1-7 megawatts of
energy per year, not enough for a large population.
 Wind farms are large numbers of wind turbines clustered
together.
The Gansu Wind Farm in China produces 6 billion kilowatt-hours of
electricity per year.
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 Wind power is comparable in cost to coal.
 Possible negative impacts of wind turbines include:
 Disruption of bird and bat migration pathways.
 Noise.
 Disruption of scenery.
21
TRADE-OFFS
Wind Power
Advantages
Moderate to high
net energy yield
High efficiency
Moderate capital
cost
Low electricity cost
(and falling)
Very low
environmental
impact
No CO2 emissions
Quick construction
Easily expanded
Disadvantages
Steady winds needed
Backup systems
needed when winds
are low
Plastic components
produced from oil
Environmental costs
not included in market
price
High land use for
wind farm
Visual pollution
Can be located at sea
Noise when located
near populated areas
Land below turbines
can be used to grow
crops or graze
livestock
Can kill birds and
interfere with flights of
migratory birds
Fig. 16-23, p. 421
23
 Geothermal power, like nuclear and coal, works by
boiling water to steam.
 Naturally-occurring
heat from the Earth
is used in place of
fuel.
 At a geothermal plant,
two wells are drilled.
 One injects cold
water towards the
underground heat.
 The second directs
steam to the turbine.
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TRADE-OFFS
Geothermal Energy
Advantages
Disadvantages
Very high efficiency
Scarcity of suitable sites
Moderate net energy
at accessible sites
Lower CO2 emissions
than fossil fuels
Can be depleted if used
too rapidly
Environmental costs
not included in market
price
CO2 emissions
Low cost at
favorable sites
Moderate to high local
air pollution
Low land use and
disturbance
Noise and odor (H2S)
Moderate
environmental
impact
High cost except at the
most concentrated and
accessible sources
Fig. 16-29, p. 428
 An enormous amount of energy (over 1,000 watts per
square meter) hits the Earth every day.
 This energy is very diffuse, spread out across the entire
surface area of the planet.
 Two separate technologies have been developed to
convert solar energy into electricity.
26
 Parabolic solar collection involves using curved reflective
surfaces that collect light and focus it onto a concentrated
point.
 The heat is absorbed and used to boil water into steam,
which spins a turbine.
27
 Photovoltaic cells
capture solar energy and
convert it directly to
electrical current.
 Solar electricity tends to
be 1.5-2 times the cost of
electricity from coal or
other renewable sources.
 Not available on
overcast days or at
night.
28
TRADE-OFFS
Passive or Active Solar Heating
Advantages
Energy is free
Net energy is
moderate (active) to
high (passive)
Quick installation
No CO2 emissions
Very low air and water
pollution
Very low land
disturbance (built
into roof or windows)
Moderate cost
(passive)
Disadvantages
Need access to sun
60% of time
Sun can be blocked
by trees and other
structures
Environmental costs
not included in market
price
Need heat storage
system
High cost (active)
Active system needs
maintenance and repair
Active collectors
unattractive
Fig. 16-11, p. 412
TRADE-OFFS
Solar Cells
Advantages
Disadvantages
Fairly high net
energy yield
Need access to sun
Work on cloudy days
Quick installation
Need electricity
storage system or
backup
Easily expanded or
moved
No CO2 emissions
Environmental costs
not included in market
price
Low environmental
impact
Last 20–40 years
Low land use (if on
roof or built into walls
or windows)
Reduces dependence
on fossil fuels
Low efficiency
High costs (but
should be competitive
in 5–15 years)
High land use (solarcell power plants)
could disrupt desert
areas
DC current must be
converted to AC
Fig. 16-20, p. 417
 Electricity generation by solar, wind, hydrokinetic, or
geothermal plants is restricted by the natural geography
of the United States.
32
 The Great Plains have the highest average wind speeds
and the greatest potential for wind power.
33
 Areas with significant elevation differences and river
courses are ideal for hydroelectricity generation.
34
 The western states are the most favorable for geothermal
energy production.
35
 The deserts of the southwest are ideal for solar electricity
generation.
36
 Besides electricity,
significant amounts
of fossil fuels are
burned for heat,
especially natural
gas.
37
 Traditionally, humans have relied on burning biomass,
such as wood, charcoal, and dung as a source of heat.
 These fuels will replenish, but produce similar levels of
pollution to fossil fuels.
 Excess demand can also lead to deforestation.
38
TRADE-OFFS
Solid 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, burned,
and replanted
sustainably
Plantation can
be located on
semiarid land
not needed for
crops
Plantation can help
restore degraded
lands
Can make use
of agricultural,
timber, and
urban wastes
Environmental costs
not included in market
price
Increases CO2
emissions if
harvested and burned
unsustainably
Low photosynthetic
efficiency
Soil erosion, water
pollution, and loss of
wildlife habitat
Plantations could
compete with cropland
Often burned in
inefficient and polluting
open fires and stoves
Fig. 16-24, p. 422
 Energy from the sun can also be gathered to use as a
source of heat.
 Passive solar heat structures have no moving parts, but
use south-facing windows to gather and absorb as much
solar heat as possible.
40
 Active solar heat structures
pump water or another
liquid through a collector.
 Can be used for household
radiant heating, or as a
source of hot water for
showers and cooking.
Image source: www.almeriaspas.com
41
 The third major energy need is fuel for transportation.
 Most of the cars, planes, and ships of the world run on
petroleum products – gasoline, diesel, etc.
42
 Vehicles can be run on other fuels besides petroleum-
based ones.
 Biofuels, like ethanol, are generated from using bacteria
or yeast to ferment plant matter.
 Currently, the biggest
source of this plant
matter is corn. This
can influence food
prices.
43
TRADE-OFFS
Biodiesel
Advantages
Reduced CO
emissions
Reduced CO2
emissions (78%)
High net energy
yield for oil palm
crops
Moderate net
energy yield for
rapeseed crops
Reduced
hydrocarbon
emissions
Better gas
mileage (40%)
Potentially
renewable
Disadvantages
Increased NOx
emissions and
more smog
Higher cost than
regular diesel
Environmental costs
not included in market
price
Low net energy yield
for soybean crops
May compete with
growing food on
cropland and raise
food prices
Loss and degradation
of biodiversity from
crop plantations
Can make engines
hard to start in cold
weather
Fig. 16-25, p. 424
TRADE-OFFS
Ethanol Fuel
Advantages
Disadvantages
High octane
Lower driving range
Some reduction in
CO2 emissions
(sugarcane bagasse)
High net energy
yield (bagasse and
switchgrass)
Reduced CO
emissions
Can be sold as E85
or pure ethanol
Low net energy yield
(corn)
Higher CO2 emissions
(corn)
Much higher cost
Environmental costs
not included in market
price
May compete with
growing food and raise
food prices
Higher NOx emissions
and more smog
Corrosive
Potentially renewable
Can make engines hard
to start in cold weather
Fig. 16-27, p. 426
 Hydrogen fuel cells use a
chemical reaction between
hydrogen and oxygen gas to
generate an electric current.
H2 + O2 → H2O
 Refueling is difficult, as pure
hydrogen is a gas and
difficult to store and
transport safely.
 No waste products are
produced, except for water
vapor.
46
TRADE-OFFS
Hydrogen
Advantages
Can be produced
from plentiful water
Disadvantages
Fuel
cell
Low environmental
impact
Renewable if produced
from renewable energy
resources
No CO2 emissions if
produced from water
Good substitute for
oil
Competitive price if
environmental and
social costs are
included in cost
comparisons
Easier to store than
electricity
Safer than gasoline
and natural gas
Nontoxic
High efficiency (45–
65%) in fuel cells
Not found as H2 in nature
Energy is needed to
produce fuel
Negative net energy
CO2 emissions if
produced from carboncontaining compounds
Environmental costs not
included in market price
Nonrenewable if
generated by fossil fuels
or nuclear power
High costs (that may
eventually come down)
Will take 25 to 50 years
to phase in
Short driving range for
current fuel-cell cars
No fuel distribution
system in place
Excessive H2 leaks may
deplete ozone in the
atmosphere
Fig. 16-31, p. 430
 Cars could be indirectly run on renewable energy if they
had powerful enough batteries to store a charge needed
to run the car for long periods of time.
 Lead-acid batteries, currently in use, are too large and do
not hold enough energy.
 Nickel-Metal Hydride batteries, used in early generation
hybrid cars, have a higher storage capacity, but will quickly
lose a stored charge when not in use.
 Lithium-ion batteries are the smallest and have the best
storage capacity, but are also expensive to produce.
The Tesla Model S runs
on lithium-ion
batteries, with a range
of 265 miles.
48
Basement
heat pump
Fig. 16-28, p. 427
 In addition to finding alternative,
renewable energy sources, it is also
important to reduce energy
consumption.
 Energy Efficiency is a measure of the
percentage of energy consumed that
actually performs the desired work.
 Incandescent light bulbs: 5-10%
efficient
 Compact fluorescent: 20-33%
efficient
 LED: 40-60% efficient
50
 Distributional surcharges are
small charges levied on all
utility customers to help
finance research and
development of renewable
energy.
 A renewable portfolio is a
state mandated minimum
percentage of energy that
utilities must get from
renewable sources.
 Green pricing is the practice
of some electricity suppliers
offering plans (at a premium)
that only use renewable
sources for electricity.
California has enacted a 33 percent
renewable portfolio standard set
for 2020.
51
 The energy star program is a federal initiative to promote
and provide incentives for purchasing more efficient
devices and appliances.
52
 Energy conservation tends to be highly tied to consumer
prices.
 In response to 1970’s oil prices, average U.S. automobile
gas-mileage increased from 13 mpg in 1975 to 28.8 mpg in
1988.
53
 Falling fuel prices in the 1980s-early 2000s discouraged
further improvements in fuel economy.
 The recent popularity of smaller cars, hybrid cars, and
electric cars has improved average MPG again.
54
SOLUTIONS
Making the Transition to a More Sustainable Energy Future
Improve Energy Efficiency
Increase fuel-efficiency
standards for vehicles,
buildings, and appliances
Mandate government
purchases of efficient
vehicles and other devices
Provide large tax credits or
feebates for buying efficient
cars, houses, and appliances
Offer large tax credits for
investments in energy
efficiency
Reward utilities for reducing
demand for electricity
Greatly increase energy
efficiency research and
development
More Renewable Energy
Greatly increase use of renewable energy
Provide large subsidies and tax credits for
use of renewable energy
Include environmental costs in prices for
all energy resources
Encourage government purchase of
renewable energy devices
Greatly increase renewable energy
research and development
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 subsidies, tax
breaks, and loan guarantees
Fig. 16-33, p. 432