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© Cengage Learning 2015

LIVING IN THE ENVIRONMENT, 18e G. TYLER MILLER • SCOTT E. SPOOLMAN


15 Nonrenewable Energy


• Oil and natural gas

– Two most widely used natural resources in

the U.S.

• Oil consumption is increasing

– New extractions from oil shale cause

environmental harm

– Burning oil and natural gas will continue

adding greenhouse gases to the atmosphere

Core Case Study: Is the United States

Entering a New Oil and Natural Gas Era?

Fig. 15-1a, p. 374

Nuclear power

8%

Geothermal,

solar, wind

biomass

2%

Hydropower

3%

Natural gas

28%

Coal

22%

Oil

37%

Fig. 15-1b, p. 374


• Energy resources vary greatly in their net

energy yields

15-1 What is Net Energy and Why Is It

Important?


• Net energy yield

– Total amount of useful energy available from a

resource minus the energy needed to make

the energy available to consumers

• Energy return on investment

– Energy obtained per unit energy used to

obtain it

Net Energy Is the Only Energy That Really

Counts


• First law of thermodynamics:

– It takes high-quality energy to get high-quality

energy

• Pumping oil from ground, refining it, and

transporting it

• Second law of thermodynamics

– Some high-quality energy is wasted at every

step

Net Energy Is the Only Energy That Really

Counts (cont’d.)


• Cannot compete in open markets with

alternatives that have higher net energy

yields

– Need subsidies from taxpayers

• Nuclear power

– The uranium fuel cycle is costly

Some Energy Resources Need Help to

Compete in the Marketplace


• Conventional crude oil is abundant and

has a medium net energy yield, but using

it causes air and water pollution and

releases greenhouse gases to the

atmosphere

– Unconventional heavy oil from oil shale rock

and tar sands exists in potentially large

supplies but has a low net energy yield and a

higher environmental impact than

conventional oil

15-2 What Are the Advantages and

Disadvantages of Oil?


• Crude oil (petroleum)

• Peak production – time after which

production from a well declines

– Global peak production for all world oil

• Crude oil cannot be used as it comes out

of the ground

– Must be refined

– Petrochemicals – byproducts

We Depend Heavily on Oil

https://www.youtube.com/watch?v=MdLVzXf7v5E

Fig. 15-4a, p. 377

Lowest Boiling Point Gases

Gasoline

Aviation fuel

Heating oil

Diesel oil

Naphtha

Heated crude oil

Grease and wax

Furnace Asphalt

Highest Boiling Point

Fig. 15-4b, p. 377


• Availability determined by:

– Demand

– Technology

– Rate at which we remove the oil

– Cost of making oil available

– Market price

• Proven oil reserves – available deposits

– Profitable

Are We Running Out of Conventional Oil?


• Unconventional heavy oil

– Higher environmental cost; production cost

• Three major options:

– Live with much higher oil prices

– Extend oil supplies

– Use other energy sources

Are We Running Out of Conventional Oil?

(cont’d.)


Fig. 15-5a, p. 379

Projected U. S. oil consumption

Bar

rels

of

oil

pe

r ye

ar (

bill

ion

s)

Arctic refuge oil output over 50 years

Year


Fig. 15-5b, p. 379


• Land disruption, greenhouse gas

emission, air pollution, water pollution, and

loss of biodiversity

• Burning oil accounts for 43% of global CO2

emissions

Use of Conventional Oil Has

Environmental Costs


Fig. 15-6, p. 380

Trade-Offs

Conventional Oil

Advantages Disadvantages

Ample supply for

several decades

Water pollution from

oil spills and leaks

Net energy yield

is medium but

decreasing

Environmental costs

not included in

market price

Low land

disruption

Releases CO2 and

other air pollutants

when burned

Efficient

distribution

system

Vulnerable to

international supply

interruptions


• The U.S.:

– Produces 9% of the world’s oil and uses 23%

of world’s oil

– Has about 2% of world’s proven oil reserves

– Imports 52% of its oil

• Should we look for more oil reserves?

– Extremely difficult

– Expensive and financially risky

Case Study: Oil Production and

Consumption in the United States


• Oil shales contain kerogen

– After distillation – shale oil

• 72% of the world’s reserve is in arid areas

of western United States

– Locked up in rock

– Lack of water needed for extraction and

processing

– Low net energy yield

Heavy Oil From Oil Shale Rock


Fig. 15-7, p. 381


• Tar sand contains bitumen

• Extensive deposits in Canada and

Venezuela

– Oil sands have more oil than in Saudi Arabia

• Extraction

– Serious environmental impact before strip-

mining

– Low net energy yield

Heavy Oil from Tar Sands


Fig. 15-8, p. 381

Fig. 15-10, p. 382

Trade-Offs

Heavy Oils from Oil Shale and Tar Sand


Large potential

supplies

Low net energy yield

Easily

transported

within and

between

countries

Releases CO2 and

other air pollutants

when produced and

burned

Efficient

distribution

system in place Severe land disruption

and high water use


• Conventional natural gas:

– Is more plentiful than oil

– Has a medium net energy yield and a fairly

low production cost

– Is a clean-burning fuel

• However, producing it has created

environmental problems


Disadvantages of Using Natural Gas?


• Natural gas – 50-90% methane CH4

• Conventional natural gas

– Liquefied petroleum gas (LPG)

• Stored in tanks

– Liquefied natural gas (LNG)

• Low net energy yield

• Makes U.S. dependent upon unstable countries

like Russia and Iran

Natural Gas Is a Useful, Clean-Burning,

but Not Problem-Free Fossil Fuel


• The U.S. produces gas conventionally and

from shale rock

– Increasing environmental problems with shale

rock extraction

Natural Gas Is a Useful, Clean-Burning,

but Not Problem-Free Fossil Fuel (cont’d.)

Fig. 15-11, p. 383

Conventional Natural Gas


Versatile fuel


for LNG

Medium net

energy yield

Production and

delivery may emit

more CO2 and CH4 per

unit of energy

produced than coal

Emits less CO2

and other air

pollutants than

other fossil fuels

when burned Potential groundwater

pollution from fracking

Trade-Offs

Fracking uses and

pollutes large

volumes of water

Ample supplies


• Fracking

– Drilling wells; using huge amounts of water,

sand, and chemicals; dealing with toxic

wastewater; transporting the natural gas

• Drinking water contaminated with natural

gas can catch fire

• Fracking has several harmful

environmental effects Fracking

Case Study: Natural Gas Production and

Fracking in the U.S.

https://www.youtube.com/watch?v=qm7e553S7fg

https://www.youtube.com/watch?v=LAxsTJd7VCA


Fig. 15-12, p. 384


Fig. 15-13, p. 385


• Coal bed methane gas

– In coal beds near the earth’s surface; in shale

beds

– High environmental impacts of extraction

• Methane hydrate

– Trapped in icy water; in permafrost

environments; on ocean floor

– Costs of extraction is currently too high

Unconventional Natural Gas


• Conventional coal is plentiful and has a

high net energy yield at low costs, but

using it results in a very high

environmental impact

– We can produce gaseous and liquid fuels

from coal, but they have lower net energy

yields and using them would result in higher

environmental impacts than those of

conventional coal


Disadvantages of Coal?


• Coal

– Solid fossil fuel

• Burned in power plants

– Generates 42% of the world’s electricity

• Abundant – world’s largest coal reserves

– United States

– Russia

– China

Coal Is a Plentiful but Dirty Fuel


• Environmental costs of burning coal

– Severe air pollution

• Sulfur released as SO2

• Large amount of soot

• CO2

• Trace amounts of mercury and radioactive

materials

• Coal Ash - LINK

Coal Is a Plentiful but Dirty Fuel (cont’d.)

https://www.youtube.com/watch?v=lHiGgtP6voM


Fig. 15-14, p. 386

Increasing moisture content Increasing heat and carbon content

Peat

(not a coal)

Lignite

(brown coal)

Bituminous

(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. 15-15a, p. 387

Waste heat

Coal bunker Turbine Cooling tower

transfers waste

heat to

atmosphere

Generator Cooling

loop

Stack

Pulverizing

mill

Condenser Filter

Boiler

Ash disposal

Fig. 15-15b, p. 387


• Coal companies and energy companies

has fought:

– Classifying carbon dioxide as a pollutant

– Classifying coal ash as hazardous waste

– Air pollution standards for emissions

• The 2008 clean coal campaign

– Note: there is no such thing as clean coal

The Clean Coal Campaign


Fig. 15-20, p. 389

Coal


Ample supplies in

many countries

Severe land

disturbance and

water pollution

Fine particle and

toxic mercury

emissions threaten

human health

Medium to high

net energy yield

Emits large amounts

of CO2 and other air

pollutants when

produced and burned

Low cost when

environmental

costs are not

included

Trade-Offs


• Nuclear power has a low environmental

impact and a very low accident risk, but its

use has been limited by:

– A low net energy yield, high costs, fear of

accidents, and long-lived radioactive wastes

– Its role in spreading nuclear weapons

technology


Disadvantages of Using Nuclear Power?


• Controlled nuclear fission reaction in a

reactor

– Light-water reactors

– Very inefficient

• Fueled by uranium ore and packed as

pellets in fuel rods and fuel assemblies

• Control rods absorb neutrons

How Does a Nuclear Fission Reactor

Work?


• Water is the usual coolant

• Containment shell around the core for

protection

• Water-filled pools or dry casks for storage

of radioactive spent fuel rod assemblies

How Does a Nuclear Fission Reactor

Work? (cont’d.)

Fig. 15-22a, p. 390

Small amounts of radioactive gases

Uranium fuel

input (reactor

core) Containment shell

Waste heat

Control rods

Heat exchanger

Steam Turbine Generator

Hot

coolant Useful electrical

energy

about 25% Hot

water

output

Coolant

Moderator Cool

water

input

Waste heat

Shielding Pressure

vessel

Coolant

passage Water Condenser

Periodic removal and storage of

radioactive wastes and spent

fuel assemblies

Periodic removal and

storage of radioactive liquid wastes

Water source

(river, lake, ocean)

LINK

https://www.youtube.com/watch?v=MGj_aJz7cTs

Fig. 15-22b, p. 390


• Mine the uranium

• Process the uranium to make the fuel

• Use it in the reactor

• Safely store the radioactive waste

• Decommission the reactor

What Is the Nuclear Fuel Cycle?

Fig. 15-23, p. 392

Fuel assemblies Decommissioning

of reactor

Enrichment

of UF6

Reactor

Fuel fabrication

(conversion of enriched UF6

to UO2 and fabrication of

fuel assemblies) Temporary storage

of spent fuel

assemblies underwater

or in dry casks Conversion

of U3O8

to UF6 Spent fuel

reprocessing

Uranium-235 as UF6

Plutonium-239 as

PuO2

Low-level radiation with long half-life

Mining uranium

ore (U3O8)

Geologic disposal of moderate and high-level radioactive wastes Open fuel cycle today

Recycling of nuclear fuel


Fig. 15-24, p. 392

Conventional Nuclear Fuel Cycle

Low environmental

impact (without

accidents)



Emits 1/6 as

much CO2 as coal

Produces long-lived,

harmful radioactive

wastes

Low risk of

accidents in

modern plants

Trade-Offs

High overall cost

Promotes spread of

nuclear weapons


Fig. 15-25, p. 393


• High-level radioactive wastes

– Must be stored safely for 10,000–240,000

years

• Where can it be stored?

– Deep burial: safest and cheapest option

– Would any method of burial last long enough?

– There is still no facility

– Shooting it into space is too dangerous

Dealing with Radioactive Nuclear Wastes

Is a Difficult Problem


• Plans in the U.S. to build a repository for

high-level radioactive wastes in the Yucca

Mountain desert region (Nevada)

• Many problems including:

– Cost of $96 billion

– Rock fractures

– Earthquake zone

– Decrease national security


Is a Difficult Problem (cont’d.)


• Dealing with old nuclear power plants:

– Decommission or retire the power plant

– Dismantle the plant and safely store the

radioactive materials

– Enclose the plant behind a physical barrier

with full-time security until a storage facility

has been built

– Enclose the plant in a tomb

• Monitor this for thousands of years


Is a Difficult Problem (cont’d.)


• Nuclear power plants – no CO2 emission

• Nuclear fuel cycle – emits CO2

• Need high rate of building new plants, and

a storage facility for radioactive wastes

Can Nuclear Power Help Reduce Climate

Change?


• Triggered by a major offshore earthquake

and resulting tsunami

• Four key human-related factors:

– No worst-case scenarios

– Seawalls too short

– Design flaws

– Relationship between plant owners and

government

Case Study: The 2011 Nuclear Power

Plant Accident in Japan

Fig. 15-27, p. 396


• Fusion

– Two isotopes fused together to form a heavier

nucleus

– Releases energy

• Technology is very difficult to develop

Is Nuclear Fusion the Answer?

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