Transcript Chapter 16
Chapter 16
Nonrenewable Energy
Chapter Overview Questions
What
are the advantages and disadvantages
of conventional oil and nonconventional
heavy oils?
What are the advantages and disadvantages
of natural gas?
What are the advantages and disadvantages
of coal and the conversion of coal to gaseous
and liquid fuels?
Chapter Overview Questions (cont’d)
What
are the advantages and disadvantages
of conventional nuclear fission, breeder
nuclear fission, and nuclear fusion?
Core Case Study:
How Long Will the Oil Party Last?
Saudi
Arabia - 10 year oil supply
Alaska’s North Slope - 6 months (U.S.: 3
years).
Alaska’s Arctic National Wildlife Refuge
(ANWR) - 1-5 months (U.S.: 7-25 months).
Core Case Study:
How Long Will the Oil Party Last?
Three
options:
Look for more
Use or waste less
Use something else.
Figure 16-1
TYPES OF ENERGY RESOURCES
99%
of the energy warms us comes from the
sun and the other 1% comes mostly from
burning fossil fuels.
Solar energy indirectly supports wind power,
hydropower, and biomass.
76%
of commercial energy comes from
nonrenewable fossil fuels (oil, natural gas,
and coal)
The remainder comes from renewable
TYPES OF ENERGY RESOURCES
Nonrenewable energy resources and geothermal
energy in the earth’s crust.
TYPES OF ENERGY RESOURCES
Commercial
energy use by source for the
world and the U.S.
Animation: Energy Use
PLAY
ANIMATION
TYPES OF ENERGY RESOURCES
Net energy = the amount of high-quality usable
energy available from a resource (minus) the
energy needed to make it available
Net Energy Ratios
The
higher the net energy ratio, the greater
the net energy available.
Ratios < 1 indicate a net energy loss.
OIL
Crude
oil (petroleum):
thick liquid containing hydrocarbons
extracted from underground deposits
separated through FRACTIONAL DISTILLATION
Only 35-50% can be economically recovered
from a deposit.
About 10-25% more can be recovered from
expensive secondary extraction techniques.
• This lowers the net energy yield.
• Only done when prices rise
OIL
Refining
crude oil:
Based on boiling
points
The most volatile
components with the
lowest boiling points
are removed at the
top.
Fractional Distillation
OIL
Eleven
OPEC (Organization of Petroleum
Exporting Countries) have 78% of the world’s
proven oil reserves and most of the world’s
unproven reserves.
After
global production peaks and begins to
decline, oil prices will rise and could threaten
the economies of countries that have not
shifted to new energy alternatives.
OIL
Inflation-adjusted
price of oil, 1950-2006.
Figure 16-6
Case Study: U.S. Oil Supplies
– world’s largest oil user – has only
2.9% of the world’s proven oil reserves.
U.S oil production peaked in 1974 (halfway
production point).
About 60% of U.S oil imports goes through
refineries in hurricane-prone regions of the
Gulf Coast.
U.S.
OIL
Burning
oil for
transportation
accounts for 43% of
global CO2
emissions.
Figure 16-7
CO2 Emissions
CO2
emissions per unit of energy produced
for various energy resources.
Figure 16-8
Heavy Oils from Oil Sand and Oil Shale:
Will Sticky Black Gold Save Us?
Oil
sand and oil shale could supplement
conventional oil
Environmental problems.
High sulfur content.
Extracting and processing:
• Toxic sludge
• Uses and contaminates larges volumes of water
• Requires large inputs of natural gas (reduces net
energy yield)
Oil Shales
Oil
shales contain
a solid
combustible
mixture of
hydrocarbons
called kerogen.
Heavy Oils
It
takes about 1.8
metric tons of oil
sand to produce
one barrel of oil.
NATURAL GAS
Natural
gas (mostly methane), is often found
above reservoirs of crude oil.
When a natural gas-field is tapped, gasses are
liquefied and removed as liquefied petroleum gas
(LPG).
Coal
beds and bubbles of methane trapped in
ice crystals deep under the arctic permafrost
and beneath deep-ocean sediments are
unconventional sources of natural gas.
NATURAL GAS
Russia
Almost half of the world’s reserves of
conventional gas
Global reserves should last 62-125 years.
Natural
and Iran
gas:
Versatile and clean-burning fuel
Releases the carbon dioxide (when burned) and
methane (from leaks) into the troposphere.
NATURAL GAS
Best
fuel to help make
the transition to
improved energy
efficiency and greater
use of renewable
energy.
COAL
Solid
fossil fuel
Formed in several stages
Buried remains of land plants (300-400mya)
The largest coal-burning power plant in the United
States in Indiana burns 23 metric tons (25 tons) of
coal per minute or three 100-car trainloads of coal per
day and produces 50% more electric power than the
Hoover Dam.
Coal bunker
Waste heat
Cooling tower
transfers waste
heat to
atmosphere
Turbine
Generator
Cooling loop
Stack
Pulverizing
mill
Condenser
Filter
Boiler
Toxic ash disposal
Fig. 16-13, p. 369
COAL
Coal
reserves in the US, Russia, and China
Hundreds to over a thousand years
Proven coal reserves:
• U.S. (27%)
• Russia (17%)
• China (13%)
2005, China & U.S. = 53% global coal consumption
COAL
Most
abundant fossil
fuel
Compared to oil and
natural gas it is not
as versatile
High environmental
impact
Releases much more
CO2 into the
troposphere.
How Would You Vote?
Should coal use be phased out over the next
20 years?
a. No. Coal is an abundant energy source and
we should continue to develop clean ways to use
it.
b. Yes. Mining and combusting coal create
serious environmental impacts.
COAL
Can
be converted into synthetic natural gas
(SNG or syngas) and liquid fuels (methanol
or synthetic gasoline) that burn cleaner than
coal.
Costs are high.
They add more CO2 to the troposphere than
burning coal.
COAL
Since
CO2 is not
regulated as an air
pollutant and costs are
high, U.S. coalburning plants are
unlikely to invest in
coal gasification.
Figure 16-15
NUCLEAR ENERGY
Isotopes
of uranium and plutonium undergo
controlled nuclear fission
Resulting heat produces steam that spins
turbines to generate electricity.
The uranium oxide consists of about 97%
nonfissionable uranium-238 and 3% fissionable
uranium-235.
The concentration of uranium-235 is increased
through an enrichment process.
Small amounts of
radioactive gases
Uranium fuel
Control rods
input (reactor
Containment shell
core)
Heat exchanger
Steam
Turbine
Generator
Electric
power
Waste heat
Hot
water
output
Coolant
Cool
water
input
Moderator
Shielding
Coolant
Pressure
passage
vessel
Periodic removal and
storage of radioactive
wastes and spent fuel
assemblies
Water
Periodic removal
and storage of
radioactive liquid
wastes
Useful energy
25%–30%
Waste heat
Condenser
Water source (river,
lake, ocean)
Fig. 16-16, p. 372
NUCLEAR ENERGY
After
three or four
years in a reactor,
spent fuel rods are
removed and stored
in a deep pool of
water contained in a
steel-lined concrete
container.
NUCLEAR ENERGY
After
spent fuel rods are cooled, they are
sometimes moved to dry-storage containers
made of steel or concrete.
Figure 16-17
Decommissioning
of reactor
Fuel assemblies
Enrichment
of UF6
Conversion of
U3O8 to UF6
Reactor
Fuel fabrication
(conversion of enriched UF6
to UO2 and fabrication of
fuel assemblies)
Uranium-235 as UF6
Plutonium-239 as PuO2
Spent fuel
reprocessing
Temporary storage of
spent fuel assemblies
underwater or in dry
casks
Low-level radiation
with long half-life
Open fuel cycle today
“Closed” end fuel cycle
Geologic disposal
of moderate &
high-level
radioactive
wastes
Fig. 16-18, p. 373
What Happened to Nuclear Power?
More
than 50 years of development
Enormous government subsidies
Still not lived up to its promise
Multi billion-dollar construction costs.
Higher operation costs and more malfunctions
than expected.
Poor management.
Public concerns about safety and stricter
government safety regulations.
Chernobyl Nuclear Power Plant Accident
World’s
worst nuclear power plant accident
occurred in 1986 in Ukraine.
Caused by poor reactor design and human
error.
By 2005, 56 people had died from radiation
released.
4,000 more are expected from thyroid cancer and
leukemia.
Animation: Chernobyl Fallout
PLAY
ANIMATION
NUCLEAR
ENERGY
World
Bank (‘95) said
nuclear power is too
costly and risky.
In 2006, it was found
that several U.S.
reactors were leaking
radioactive tritium into
groundwater.
Figure 16-19
NUCLEAR
ENERGY
A
1,000
megawatt nuclear
plant is refueled
once a year,
whereas a coal
plant requires 80
rail cars a day.
Figure 16-20
NUCLEAR ENERGY
Terrorists
could attack nuclear power plants (especially
poorly protected pools and casks that store spent
nuclear fuel rods.)
could wrap explosives around small amounts of
radioactive materials that are fairly easy to get,
detonate such bombs, and contaminate large
areas for decades.
NUCLEAR ENERGY
Decommissioning
–
When a nuclear reactor reaches the end of its
useful life
highly radioactive materials must be kept from
reaching the environment for thousands of years.
At
least 228 large commercial reactors
worldwide (20 in the U.S.) are scheduled for
retirement by 2012.
Many applying to extend 40-yr license to 60 yrs
Aging reactors - embrittlement and corrosion.
NUCLEAR ENERGY
Does
not lessen dependence on imported oil
Will not reduce CO2 emissions as much as
others
The nuclear fuel cycle contributes to CO2
emissions.
Wind turbines, solar cells, geothermal energy,
and hydrogen contributes much less to CO2
emissions.
NUCLEAR ENERGY
Scientists
disagree about the best methods
for long-term storage of high-level radioactive
waste:
Bury it deep underground.
Shoot it into space.
Bury it in the Antarctic ice sheet.
Bury it in the deep-ocean floor that is geologically
stable.
Change it into harmless or less harmful isotopes.
New and Safer Reactors
Pebble bed
modular
reactor
(PBMR) are
smaller
reactors that
minimize the
chances of
runaway chain
reactions.
Figure 16-21
New and Safer Reactors
Some
oppose the pebble reactor due to :
A crack in the reactor could release radioactivity.
The design has been rejected by UK and
Germany for safety reasons.
Lack of containment shell would make it easier
for terrorists to blow it up or steal radioactive
material.
Creates higher amount of nuclear waste and
increases waste storage expenses.
NUCLEAR ENERGY
Nuclear
fusion is a nuclear change in which
two isotopes are forced together.
No risk of meltdown or radioactive releases.
May also be used to breakdown toxic material.
Still in laboratory stages.
There
is a disagreement over whether to
phase out nuclear power or keep this option
open in case other alternatives do not pan
out.
How Would You Vote?
Should nuclear power be phased out in the
country where you live over the next 20 to 30
years?
a. No. In many countries, there are no suitable
energy alternatives to nuclear fission.
b. Yes. Nuclear fission is too expensive and
produces large quantities of very dangerous
radioactive wastes.