Transcript Chapter 16

Chapter 16
Nonrenewable Energy Resources
Energy resources
99% of energy used to heat the earth
and all the buildings comes from the
sun
The sun also creates renewable energy
resources – wind, flowing water,
biomass
The rest
 The last 1% comes from fuel resources
 Fossil fuels make up the vast majority
 Petroleum, coal, and natural gas
 A small portion also comes from nuclear sources
Is it getting hot in here?
Which energy source has the highest
net energy ratio for space heating?
Passive solar, yes, just letting in sunlight to
warm a room is the most efficient
 Which energy source has the highest net
energy ratio for high-temperature industrial
uses?
 coal
Beep, Beep
The highest net energy ratio for
transportation
Natural gas
Unfortunately, current NG cars have limited
driving ranges and limited fueling sites.
Oil and Natural Gas
Floating oil drilling
platform
Oil drilling
platform
on legs
Gas well
Oil storage
Oil well
Valves
Pipeline
Pump
Impervious rock
Natural gas
Oil
Water
Coal
Geothermal Energy
Hot water
Contour
storage
strip mining
Geothermal
power plant
Area strip
Pipeline
mining
Drilling
Mined coal
tower
Water
penetrates
Underground
coal mine
down
Water is heated
through
and brought up
the
as dry steam or
rock
wet steam
Coal seam
Hot rock
Water
Magma
Fig. 14.11, p. 332
What is this stuff?
Petroleum is a gooey liquid consisting of
primarily hydrocarbons
Also called crude oil (or just oil)
Oil is widely used because it is cheap, easily
transported and has a high net energy yield
Through distillation we produce many
products - asphalt, heating oil, diesel,
gasoline, grease, wax, natural gas
Shifts in energy usage
worldwide
During the 20th century
Coal use dropped from 55 to 22%
Oil increased from 2 to 30%
Natural gas rose from 1 to 23%
Nuclear rose from 0 to 6%
Renewable (wood and water ) dropped
from 42 to 19%
Way to go US
 The U.S. is the world’s largest energy consumer
 We use 25% of the world’s energy (even though we
only have 4.5% of the total population)
 India with 17% of the population only uses 3% of
the world’s commercial energy
 91% of the U.S.’s energy in nonrenewable
Energy
Net energy refers to the amount of useful
energy minus the energy needed to find,
extract, process, concentrate, and transport
to the users
Nuclear energy has a low net energy ratio
because it is expensive to extract and process
uranium, convert it into a fuel, build and
operate the plant, and dismantle and deal
with radioactive plants and waste
Oil, Oil everywhere and not a
drop to drink
Extracted as crude oil or petroleum, a
thick liquid consisting of hydrocarbons,
and some sulfur, oxygen and nitrogen
impurities
Produced from decayed plant and
animal material over millions of years
Oil continued
Normally crude oil is not found in
underground pools, but is spread out in
the pores and cracks within rock deep
beneath the ground
Primary recovery – drill a hole and
pump out the light weight crude that
fills the hole
Oil continued
Secondary recovery – pumping water into the
well to force oil out of the pores
The oil and water mixture is separated after
pumping
Only about 35% of the oil is removed by
primary and secondary recovery
Oil continued
Tertiary recovery – either a heated gas
or a liquid detergent is pumped into the
well to help remove more oil
Tertiary is expensive
Oil continued
 At the refinery oil is converted into petrochemicals
and used as a resource to create industrial organic
chemicals, pesticides, plastics, synthetic fibers,
paints, medicines and more.
 OPEC – organization of petroleum exporting countries
control 67% of the worlds oil and maintain control
over pricing
Ticket to Ride
Most oil in the US is used for
transportation
Gasoline
Diesel
Lubricant oil and grease
Some as LNG
Gases
Gasoline
Aviation fuel
Heating oil
Heated
crude oil
Diesel oil
Naphtha
Furnace
Grease
and wax
Asphalt
Fig. 14.16, p. 337
Advantages
Ample supply for
42–93 years
Low cost (with
huge subsidies)
High net
energy yield
Easily transported
within and
between countries
Low land use
Disadvantages
Need to find
substitute within
50 years
Artificially low
price encourages
waste and
discourages
search for
alternatives
Air pollution
when burned
Releases CO2
when burned
Moderate water
pollution
Fig. 14.21, p. 340
Oil continued
 Oil shale is a fine grained sedimentary rock containing solid
combustible organic material (waxy hydrocarbons) called
kerogen
 Shale oil is made from heating oil shale
 Tar sand contains bitumen (a high sulfur heavy oil) another
combustible organic material
 Both are more expensive than crude recovery because it
requires more energy, land disruption, and are more difficult to
extract, produce roughly the same oil but with lower net energy
yield
Oh, Canada
 There is a lot of shale oil and tar sands in North
America, particularly in Canada.
 As the price of crude oil goes up, the value of this
heavy oil also goes up and becomes economically
profitable to extract.
 Unfortunately, almost all vegetation above the
reserves must be removed to obtain these resources,
so the environmental cost is very high
Domestic Oil
US extraction of oil has decreased since
1985, thus increasing our reliance on
other countries
Switching to alternative fuels sources
helps maintain our economic
independence
Advantages
Moderate existing
supplies
Large potential
supplies
Disadvantages
High costs
Low net energy
yield
Large amount of
water needed to
process
Severe land
disruption from
surface mining
Water pollution
from mining
residues
Air pollution
when burned
CO2 emissions
when burned
Fig. 14.25, p. 342
Natural Gas
Mostly CH4 methane with some ethane,
propane and butane and small amounts
of hydrogen sulfide (toxic)
LPG (liquefied petroleum gas) the
propane and butane are removed from
natural gas and stored under pressure
How long will it last?
Natural gas should last about 125 years
worldwide
About 75 years in the US
Overall about 200-300 years with rising
prices, better technology, and more
discoveries
Advantages
Disadvantages
Ample supplies
(125 years)
Releases CO2
when burned
High net energy
yield
Methane
(a greenhouse
gas) can leak
from pipelines
Low cost (with
huge subsidies)
Less air pollution
than other
fossil fuels
Lower CO2
emissions than
other fossil fuels
Shipped across
ocean as highly
explosive LNG
Sometimes
burned off and
wasted at wells
because of low
price
Moderate environmental impact
Easily transported
by pipeline
Low land use
Good fuel for
fuel cells and
gas turbines
Fig. 14.26, p. 342
The future of power plants
There is currently being developed a
combined cycle natural gas electric
power plant with 60% efficiency
This is much better than 32-40%
efficiency of others (coal, oil, nuke)
What other reasons make it better?
Coal
Solid fuel of combustible carbon, most
formed 285-360 million years ago
Peat – 1st, low heat content
Lignite – 2nd, low heat and low sulfur
Bituminous Coal – 3rd, high heat and
abundant supply, high sulfur
Anthracite – 4th, high heat, low sulfur,
limited supply
Increasing heat and carbon content
Increasing moisture content
Peat
(not a coal)
Lignite
(brown coal)
Bituminous Coal
(soft coal)
Anthracite
(hard coal)
Heat
Heat
Heat
Pressure
Pressure
Pressure
Partially decayed
plant matter in swamps
and bogs; low heat
content
Low heat content;
low sulfur content;
limited supplies in
most areas
Extensively used
as a fuel because
of its high heat content
and large supplies;
normally has a
high sulfur content
Highly desirable fuel
because of its high
heat content and
low sulfur content;
supplies are limited
in most areas
Fig. 14.27, p. 344
Coal for energy
Coal provides about 22% of the
commercial energy in the world
It is used to create 62% of the worlds
electricity
75% of the worlds steel
China is the largest user followed by US
US creates 52% of energy with coal
Advantages
Ample supplies
(225–900 years)
High net energy
yield
Low cost (with
huge subsidies)
Disadvantages
Very high
environmental
impact
Severe land
disturbance, air
pollution, and
water pollution
High land use
(including mining)
Severe threat to
human health
High CO2
emissions
when burned
Releases
radioactive
particles and
mercury into air
Fig. 14.28, p. 344
The cost of coal
 Land disturbance
 Air pollution (especially sulfur dioxide)
 Co2 emissions
 Water pollution
 Electricity production (coal) is the second largest
producer of toxic emissions
 The most deadly emission is mercury
Wonderful coal
60,000 babies annually are born with brain
damage due to mercury exposure, typically
from pregnant mothers eating mercury in fish
Coal also releases more radioactive particles
into the atmosphere than nuclear power
plants
Also, acid rain and methane release
Coal in the US
Air pollutants kill thousands (estimates
are from 60,000 – 200,000)
Cause at least 50,000 cases of
respiratory disease
Cost several billion dollars in property
damage
The good news
Fluidized bed combustion is reducing
the amount of pollution
Hot air is blown under a mix of crushed
limestone and coal while it is burnt
This removes most sulfur dioxide,
reduces Nox and burns the coal more
efficiently and cheaply
Flue gases
Coal
Limestone
Steam
Fluidized bed
Water
Air nozzles
Air
Calcium sulfate
and ash
Fig. 14.29, p. 345
Coal gasification
Solid coal can be converted into
synthetic natural gas (SNG)
It can also be made into synfuels
(liquids) through coal liquefaction
Neither is expected to play a major role
in our future energy needs
Raw coal
Remove dust,
tar, water, sulfur
Air or
oxygen
Raw gases
Steam
2C + O2
Coal
Pulverizer
CO + 3H2
2CO
CH4 + H2O
Methane
(natural gas)
Recover
sulfur
Clean
Methane
gas
Recycle unreacted
carbon (char)
Slag removal
Pulverized coal
Fig. 14.30, p. 345
Advantages
Disadvantages
Large potential
supply
Low to moderate
net energy yield
Vehicle fuel
Higher cost than
coal
High
environmental
impact
Increased surface
mining of coal
High water use
Higher CO2
emissions than
coal
Fig. 14.31, p. 346
Nuclear Energy
Uranium 235 and plutonium 239 are
split (nucleus) to release energy
The reaction rate is controlled
The energy heats water and turns it to
steam
Steam spins turbines connected to
generators which create electricity
LWR light water reactors
All US reactors are of this type, so know
it
Small amounts of Radioactive gases
Uranium fuel input
(reactor core)
Containment shell
Waste heat
Emergency core
Cooling system
Electrical power
Steam
Control
rods
Turbine
Heat
exchanger
Hot coolant
Useful energy
25 to 30%
Generator
Hot water output
Condenser
Pump
Pump
Coolant
Cool water input
Black
Moderator
Water
Pump
Waste
heat
Coolant
passage
Pressure
vessel
Shielding
Periodic removal
and storage of
radioactive wastes
and spent fuel assemblies
Periodic removal
and storage of
radioactive liquid wastes
Waste
Water source
heat
(river, lake, ocean)
Fig. 14.32, p. 346
Nuclear is out of favor (unless
you ask Bush)
The US has not ordered a new nuclear facility
since 1978, and 120 ordered since 1973 were
cancelled
Most countries are phasing out nuclear plants
or are not continuing to expand their
programs, except China who is trying to move
away from dependence on coal
Why is nuclear not meeting
expectations?
 Multi-billion dollar cost of construction
 Strict govt. safety regulations
 High operating costs
 More malfunctions than expected
 Poor management
 Public concern after Chernobyl, and Three Mile Island
 Investor concern about economic feasibility
Advantages
Large fuel
supply
Disadvantages
High cost (even
with large
subsidies)
Low
environmental
impact (without
accidents)
Low net
energy yield
Emits 1/6 as
much CO2 as coal
High
environmental
impact (with major
accidents)
Moderate land
disruption and
water pollution
(without
accidents)
Catastrophic
accidents can
happen
(Chernobyl)
Moderate land use
Low risk of
accidents
because of
multiple
safety systems
(except in 35
poorly designed
and run reactors
in former Soviet
Union and
Eastern Europe)
No acceptable
solution for
long-term storage
of radioactive
wastes and
decommissioning
worn-out plants
Spreads
knowledge and
technology for
building nuclear
weapons
Fig. 14.35, p. 349
Coal
Ample supply
High net energy
yield
Very high air
pollution
High CO2
emissions
65,000 to 200,000
deaths per year
in U.S.
High land
disruption from
surface mining
High land use
Low cost (with
huge subsidies)
Nuclear
Ample supply
of uranium
Low net energy
yield
Low air pollution
(mostly from fuel
reprocessing)
Low CO2
emissions
(mostly from fuel
reprocessing)
About 6,000
deaths per
year in U.S.
Much lower land
disruption from
surface mining
Moderate land
use
High cost (with
huge subsidies)
Fig. 14.36, p. 349
Chernobyl
 In the former Soviet Union, April 26, 1986 the reactor
core went out of control and exploded sending a
cloud of radioactive dust into the atmosphere
 3,576 – 32,000 people died
 400,000 forced to evacuate
 62,000 square miles still contaminated
 More than 500,000 people exposed to high level
radiation
 Cost the govt. $385 billion
Three Mile Island
March 29, 1979 in Harrisburg, Penn.
Coolant failed and core melted
Radioactive material escaped into air
50,000 people evacuated
Luckily the radiation release was
believed to be too low to cause death
or cancer
Cleanup has cost $1.2 billion so far
What do we do with the
waste?
 Low level radioactive waste must be stored for 100500 years until it reaches a safe level (does not give
off harmful ionizing radiation)
 This was done by sealing the waste in steel drums
and dumping it in the ocean
 Today some countries (US) stores the waste at govt.
run landfills, but no one wants to live anywhere near
them
Waste container
2 meters wide
2–5 meters high
Several
steel drums
holding waste
Steel wall
Fig. 14.38a, p. 351
Steel wall
Lead shielding
Up to 60
deep trenches
dug into clay.
As many as 20
flatbed trucks
deliver waste
containers daily.
Barrels are stacked
and surrounded
with sand. Covering
is mounded to aid
rain runoff.
Clay bottom
Fig. 14.38b, p. 351
And the bad stuff?
High level radioactive waste must be
stored for 10,000 to 240,000 years until
it reaches a safe level
Currently most is stored at the reactor
site, sealed in drums, in pools of water
Proposed methods of disposal
 Bury deep underground – this is the leading strategy
currently
 Shoot it into space/Sun
 Bury it deep in the Antarctic ice sheet
 Dump it into descending subduction zones
 Bury in deep mud deposits on ocean floor
 Convert into less harmful isotopes (currently we do
not have the technology)
Storage C ontainers
Fuel rod
P e rso n n e l e le v a to r
2 ,5 0 0 ft.
(7 6 0 m )
deep
Prim ary canister
A ir sh a ft
N u cle a r w a ste s h a ft
O verpack container
sealed
F ig . 1 4 .3 9 b , p . 3 5 2
Fig. 14.39c, p. 352
S lid e 5 2
Slide 53
Fig.
Radioactive contamination
The EPA suggests that there are 45,000
sites in the US (20,000 belong to the
DOE)
It is expected to cost over $230 billion
over the next 75 years
More than 144 highly contaminated
weapons construction sites will never be
completely cleaned