MILLER/SPOOLMAN LIVING IN THE ENVIRONMENT€¦ · Coal liquefaction 1.4 Oil shale 1.2 . Energy Resources With Low/Negative Net Energy Yields Need Marketplace Help •Cannot compete

17TH MILLER/SPOOLMAN

LIVING IN THE ENVIRONMENT

Chapter 15

Nonrenewable Energy

Case Study: A Brief History of Human Energy Use

• Everything runs on energy

• Industrial revolution began 275 years ago, relied on

wood, which led to deforestation

• Coal

• Petroleum products

• Natural gas

• All of these are nonrenewable energy resources

Energy Use: World and United States

Fig. 15-1, p. 370

Fig. 15-1, p. 370

Nuclear power 6%

Geothermal, solar, wind 1%

Hydropower 3%

Natural gas 21%

Coal 24% Biomass 11%

Oil 34%

World

Fig. 15-1, p. 370

Nuclear power 8%

Coal 22%

Natural gas 23%

Hydropower, 3%

Oil 40%

Biomass 3%

United States

Geothermal, solar, wind 1%

15-1 What is Net Energy and Why Is It Important?

• Concept 15-1 Net energy is the amount of high-quality energy available from an energy resource minus the amount of energy needed to make it available.

Basic Science: Net Energy Is the Only Energy That Really Counts (1)

• First law of thermodynamics:

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

• Pumping oil from ground, refining it, transporting it

• Second law of thermodynamics

• Some high-quality energy is wasted at every step

Basic Science: Net Energy Is the Only Energy That Really Counts (2)

• Net energy

• Total amount of useful energy available from a resource minus the energy needed to make the energy available to consumers

• Business net profit: total money taken in minus all expenses

• Net energy ratio: ratio of energy produced to energy used to produce it

• Conventional oil: high net energy ratio

It Takes Energy to Pump Petroleum

Fig. 15-2, p. 372

Net Energy Ratios

Fig. 15-3, p. 373

Fig. 15-3a, p. 373

Space Heating

Passive solar 5.8

Natural gas 4.9

Oil 4.5

Active solar 1.9

Coal gasification 1.5

Electric heating (coal-fired plant) 0.4

Electric heating (natural-gas-fired plant)

0.4

Electric heating (nuclear plant) 0.3

Fig. 15-3b, p. 373

High-Temperature Industrial Heat

Surface-mined coal 28.2

Underground- mined coal

25.8

Natural gas 4.9

Oil 4.7

Coal gasification 1.5

Direct solar (concentrated) 0.9

Fig. 15-3c, p. 373

Transportation

Natural gas 4.9

Gasoline (refined crude oil)

4.1

Biofuel (ethanol) 1.9

Coal liquefaction 1.4

Oil shale 1.2

Energy Resources With Low/Negative Net Energy Yields Need Marketplace Help

• Cannot compete in open markets with alternatives that have higher net energy yields

• Need subsidies from taxpayers

• Nuclear power as an example

Reducing Energy Waste Improves Net Energy Yields and Can Save Money

• 84% of all commercial energy used in the U.S. is wasted

• 43% after accounting for second law of thermodynamics

• Drive efficient cars, not gas guzzlers

• Make buildings energy efficient

15-2 What Are the Advantages and Disadvantages of Oil?

• Concept 15-2A Conventional oil is currently abundant, has a high net energy yield, and is relatively inexpensive, but using it causes air and water pollution and releases greenhouse gases to the atmosphere.

• Concept 15-2B Heavy oils from tar sand and oil shale exist in potentially large supplies but have low net energy yields and higher environmental impacts than conventional oil has.

We Depend Heavily on Oil (1)

• Petroleum, or crude oil: conventional, or light oil

• Fossil fuels: crude oil and natural gas

• Peak production: time after which production from a well declines

• Global peak production for all world oil

We Depend Heavily on Oil (2)

• Oil extraction and refining

• By boiling point temperature

• Petrochemicals:

• Products of oil distillation

• Raw materials for industrial organic chemicals

• Pesticides

• Paints

• Plastics

Science: Refining Crude Oil

Fig. 15-4, p. 375

Fig. 15-4a, p. 375

Lowest Boiling Point Gases

Gasoline

Aviation fuel

Heating oil

Diesel oil

Naphtha

Heated crude oil

Grease and wax

Furnace Asphalt

Highest Boiling Point

How Long Might Supplies of Conventional Crude Oil Last? (1)

• Rapid increase since 1950

• Largest consumers in 2009

• United States, 23%

• China, 8%

• Japan, 6%

How Long Might Supplies of Conventional Crude Oil Last? (2)

• Proven oil reserves

• Identified deposits that can be extracted profitably with current technology

• Unproven reserves

• Probable reserves: 50% chance of recovery

• Possible reserves: 10-40% chance of recovery

• Proven and unproven reserves will be 80% depleted sometime between 2050 and 2100

World Oil Consumption, 1950-2009

Figure 1, Supplement 2

History of the Age of Conventional Oil


OPEC Controls Most of the World’s Oil Supplies (1)

• 13 countries have at least 60% of the world’s crude oil reserves

• Saudi Arabia: 20%

• United States: 1.5%

• Global oil production leveled off in 2005

• Oil production peaks and flow rates to consumers

OPEC Controls Most of the World’s Oil Supplies (2)

• Three caveats when evaluating future oil supplies

1. Potential reserves are not proven reserves

2. Must use net energy yield to evaluate potential of any oil deposit

3. Must take into account high global use of oil

Crude Oil in the Arctic National Wildlife Refuge

Fig. 15-5, p. 376

Fig. 15-5a, p. 376

14

13

12

11

10

9 Projected U. S. oil consumption

8

7

6

5

Bar

rels

of

oil

pe

r ye

ar (

bill

ion

s)

4

3

2 Arctic refuge oil output over 50 years

1

0 2010 2020 2030 2040 2050

Year

2000

The United States Uses Much More Oil Than It Produces

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

• 1.5% of world’s proven oil reserves

• Imports 52% of its oil

• Should we look for more oil reserves? • Extremely difficult

• Expensive and financially risky

U.S. Energy Consumption by Fuel


Proven and Unproven Reserves of Fossil Fuels in North America


Conventional Oil Has Advantages and Disadvantages

• Extraction, processing, and burning of nonrenewable oil and other fossil fuels

• Advantages

• Disadvantages

Trade-Offs: Conventional Oil

Fig. 15-6, p. 377

Fig. 15-6, p. 377

Trade-Offs

Conventional Oil

Advantages Disadvantages

Ample supply for several decades

Water pollution from oil spills and leaks

High net energy yield but decreasing

Environmental costs not included in market price

Low land disruption

Releases CO 2 and other air pollutants when burned

Efficient distribution system

Vulnerable to international supply interruptions

Bird Covered with Oil from an Oil Spill in Brazilian Waters

Fig. 15-7, p. 377

Case Study: Heavy Oil from Tar Sand

• Oil sand, tar sand contains bitumen

• Canada and Venezuela: oil sands have more oil than in Saudi Arabia

• Extraction

• Serious environmental impact before strip-mining

• Low net energy yield: Is it cost effective?

Strip Mining for Tar Sands in Alberta

Fig. 15-8, p. 378

Will Heavy Oil from Oil Shales Be a Useful Resource?

• 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

Oil Shale Rock and the Shale Oil Extracted from It

Fig. 15-9, p. 379

Trade-Offs: Heavy Oils from Oil Shale and Oil Sand

Fig. 15-10, p. 379

Fig. 15-10, p. 379

Trade-Offs

Heavy Oils from Oil

Shale and Tar Sand


Large potential supplies

Low net energy yield

Easily transported within and between countries

Releases CO 2 and other air pollutants when produced and burned

Efficient distribution system in place

Severe land disruption and high water use

15-3 What Are the Advantages and Disadvantages of Using Natural Gas? • Concept 15-3 Conventional natural gas is more

plentiful than oil, has a high net energy yield and a fairly low cost, and has the lowest environmental impact of all fossil fuels.

Natural Gas Is a Useful and Clean-Burning Fossil Fuel

• Natural gas: mixture of gases

• 50-90% is methane -- CH4

• Conventional natural gas

• Pipelines

• Liquefied petroleum gas (LPG)

• Liquefied natural gas (LNG)

• Low net energy yield

• Makes U.S. dependent upon unstable countries like Russia and Iran

Natural Gas Burned Off at Deep Sea Oil Well

Fig. 15-11, p. 380

Is Unconventional Natural Gas the Answer? • Coal bed methane gas

• In coal beds near the earth’s surface

• In shale beds

• High environmental impacts or extraction

• Methane hydrate

• Trapped in icy water

• In permafrost environments

• On ocean floor

• Costs of extraction currently too high

Trade-Offs: Conventional Natural Gas

Fig. 15-12, p. 381

Fig. 15-12, p. 381

Conventional Natural Gas


Ample supplies Low net energy yield for LNG

High net energy yield

Releases CO2 and other air pollutants when burned

Emits less CO2 and other pollutants than other fossil fuels

Difficult and costly to transport from one country to another

Trade-Offs

Methane Hydrate

Fig. 15-13, p. 381

15-4 What Are the Advantages and Disadvantages of Coal?

• Concept 15-4A Conventional coal is plentiful and has a high net energy yield and low cost, but it has a very high environmental impact.

• Concept 15-4B Gaseous and liquid fuels produced from coal could be plentiful, but they have lower net energy yields and higher environmental impacts than conventional coal has.

Coal Is a Plentiful but Dirty Fuel (1)

• Coal: solid fossil fuel

• Burned in power plants; generates 42% of the world’s electricity

• Inefficient

• Three largest coal-burning countries

• China

• United States

• Canada

Coal Is a Plentiful but Dirty Fuel (2)

• World’s most abundant fossil fuel

• U.S. has 28% of proven reserves

• Environmental costs of burning coal

• Severe air pollution

• Sulfur released as SO2

• Large amount of soot

• CO2

• Trace amounts of Hg and radioactive materials

Stages in Coal Formation over Millions of Years

Fig. 15-14, p. 382

Fig. 15-14, p. 382

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

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

Stepped Art

Fig. 15-14, p. 382

Science: Coal-Burning Power Plant

Fig. 15-15, p. 382

Fig. 15-15b, p. 382

Waste heat

Coal bunker Turbine Cooling tower transfers waste heat to atmosphere

Generator

Cooling loop

Stack

Pulverizing mill Condenser Filter

Boiler

Toxic ash disposal

Air Pollution from a Coal-Burning Industrial Plant in India

Fig. 15-16, p. 383

CO2 Emissions Per Unit of Electrical Energy Produced for Energy Sources

Fig. 15-17, p. 383

Fig. 15-17, p. 383

Coal-fired electricity 286%

Synthetic oil and gas produced from

coal 150%

Coal 100%

Tar sand 92%

Oil 86%

58% Natural gas

Nuclear power fuel cycle 17%

Geothermal 10%

Coal-fired

electricity 286%

Synthetic oil and

gas produced

from coal

150%

Coal 100%

Tar sand 92%

Oil 86%

Natural gas 58%

Nuclear power

fuel cycle 17%

Geothermal 10% Stepped Art

Fig. 15-17, p. 383

World Coal and Natural Gas Consumption, 1950-2009


Coal Consumption in China and the United States, 1980-2008


Coal Deposits in the United States


Trade-Offs: Coal

Fig. 15-18, p. 384

Fig. 15-18, p. 384

Coal


Ample supplies in many countries

Severe land disturbance and water pollution

Fine particle and toxic mercury emissions threaten human health

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

Case Study: The Problem of Coal Ash

• Highly toxic

• Arsenic, cadmium, chromium, lead, mercury

• Ash left from burning and from emissions

• Some used as fertilizer by farmers

• Most is buried or put in ponds

• Contaminates groundwater

• Should be classified as hazardous waste

The Clean Coal and Anti-Coal Campaigns • Coal companies and energy companies fought

• Classifying carbon dioxide as a pollutant

• Classifying coal ash as hazardous waste

• Air pollution standards for emissions

• 2008 clean coal campaign

• But no such thing as clean coal

• “Coal is the single greatest threat to civilization and all life on the planet.” – James Hansen

We Can Convert Coal into Gaseous and Liquid Fuels

• Conversion of solid coal to

• Synthetic natural gas (SNG) by coal gasification

• Methanol or synthetic gasoline by coal liquefaction

• Synfuels

• Are there benefits to using these synthetic fuels?

Trade-Offs: Synthetic Fuels

Fig. 15-19, p. 385

Fig. 15-19, p. 385

Synthetic Fuels


Large potential supply in many countries

Low to moderate net energy yield

Vehicle fuel

Requires mining 50% more coal with increased land disturbance, water pollution and water use

Lower air pollution than coal Higher CO2 emissions

than coal

Trade-Offs

15-5 What Are the Advantages and Disadvantages of Nuclear Energy?

• Concept 15-5 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, long-lived radioactive wastes, and the potential for spreading nuclear weapons technology.

How Does a Nuclear Fission Reactor Work? (1)

• 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? (2)

• 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

Water-Cooled Nuclear Power Plant

Fig. 15-20, p. 387

Fig. 15-20a, p. 387

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)

Fission of Uranium-235

Fig. 2-9b, p. 43

Fig. 2-9b, p. 43

Nuclear fission

Uranium-235

Uranium-235

Neutron Energy

Fission fragment

n

n

n

n

n n

Energy

Energy

Energy

Fission fragment

Radioactive isotope Radioactive decay occurs when nuclei of unstable isotopes spontaneously emit fast-moving chunks of matter (alpha particles or beta particles), high-energy radiation (gamma rays), or both at a fixed rate. A particular radioactive isotope may emit any one or a combination of the three items shown in the diagram.

What Is the Nuclear Fuel Cycle?

1. Mine the uranium

2. Process the uranium to make the fuel

3. Use it in the reactor

4. Safely store the radioactive waste

5. Decommission the reactor

Science: The Nuclear Fuel Cycle

Fig. 15-21, p. 388

Fig. 15-21, p. 388

Fuel assemblies Decommissioning of reactor

Enrichment of UF6

Reactor

Fuel fabrication

(conversion of enriched UF 6 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

What Happened to Nuclear Power?

• Slowest-growing energy source and expected to decline more

• Why? • Economics

• Poor management

• Low net yield of energy of the nuclear fuel cycle

• Safety concerns

• Need for greater government subsidies

• Concerns of transporting uranium

Global Energy Capacity of Nuclear Power Plants


Nuclear Power Plants in the United States


Case Study: Chernobyl: The World’s Worst Nuclear Power Plant Accident

• Chernobyl

• April 26, 1986

• In Chernobyl, Ukraine

• Series of explosions caused the roof of a reactor building to blow off

• Partial meltdown and fire for 10 days

• Huge radioactive cloud spread over many countries and eventually the world

• 350,000 people left their homes

• Effects on human health, water supply, and agriculture

Nuclear Power Has Advantages and Disadvantages

• Advantages

• Disadvantages

Trade-Offs: Conventional Nuclear Fuel Cycle

Fig. 15-22, p. 389

Fig. 15-22, p. 389

Conventional Nuclear Fuel Cycle

Low environmental impact (without accidents)

Very low net energy yield and high overall cost


Emits 1/6 as much CO2 as coal

Produces long-lived, harmful radioactive wastes

Low risk of accidents in modern plants

Promotes spread of nuclear weapons

Trade-Offs

Trade-Offs: Coal versus Nuclear to Produce Electricity

Fig. 15-23, p. 389

Fig. 15-23, p. 389

Coal vs. Nuclear

High net energy yield Very low net energy yield

Coal Nuclear

Very high emissions of CO2 and other air pollutants

Low emissions of CO2 and other air pollutants

High land disruption from surface mining

Much lower land disruption from surface mining

Low cost when environmental costs are not included

High cost (even with huge subsidies)

Trade-Offs

Storing Spent Radioactive Fuel Rods Presents Risks

• Rods must be replaced every 3-4 years

• Cooled in water-filled pools

• Placed in dry casks

• Must be stored for thousands of years

• Vulnerable to terrorist attack

Dealing with Spent Fuel Rods

Fig. 15-24, p. 390

Dealing with Radioactive Wastes Produced by Nuclear Power Is a Difficult Problem

• High-level radioactive wastes • Must be stored safely for 10,000–240,000 years

• Where to store it • 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

Case Study: High-Level Radioactive Wastes in the United States

• 1985: plans in the U.S. to build a repository for high-level radioactive wastes in the Yucca Mountain desert region (Nevada)

• Problems

• Cost: $96 billion

• Large number of shipments to the site: protection from attack?

• Rock fractures

• Earthquake zone

• Decrease national security

What Do We Do with Worn-Out Nuclear Power Plants?

• Decommission or retire the power plant

• Some options

1. Dismantle the plant and safely store the radioactive materials

2. Enclose the plant behind a physical barrier with full-time security until a storage facility has been built

3. Enclose the plant in a tomb

• Monitor this for thousands of years

Can Nuclear Power Lessen Dependence on Imported Oil & Reduce Global Warming?

• Nuclear power plants: no CO2 emission

• Nuclear fuel cycle: emits CO2

• Opposing views on nuclear power

• Nuclear power advocates

• 2007: Oxford Research Group

• Need high rate of building new plants, plus a storage facility for radioactive wastes

Are New Generation Nuclear Reactors the Answer?

• Advanced light-water reactors (ALWR) • Built-in passive safety features

• Thorium-based reactors • Cheaper and safer

• But much research and development needed

Solutions: New Generation Nuclear Reactors

Fig. 15-25, p. 393

Will Nuclear Fusion Save Us?

• “Nuclear fusion • Fuse lighter elements into heavier elements

• No risk of meltdown or large radioactivity release

• Still in the laboratory phase after 50 years of research and $34 billion dollars

• 2006: U.S., China, Russia, Japan, South Korea, and European Union • Will build a large-scale experimental nuclear fusion

reactor by 2018

Nuclear Fusion

Fig. 2-9c, p. 43

Fig. 2-9c, p. 43

Nuclear fusion occurs when two isotopes of light elements, such as hydrogen, are forced together at extremely high temperatures until they fuse to form a heavier nucleus and release a tremendous amount of energy.

Hydrogen-3 (tritium nucleus)

100 million °C

Reaction conditions

Neutron

Energy

Products

Neutron

Nuclear fusion

Fuel

Hydrogen-2 (deuterium nucleus)

Helium-4 nucleus Proton

Experts Disagree about the Future of Nuclear Power

• Proponents of nuclear power

• Fund more research and development

• Pilot-plant testing of potentially cheaper and safer reactors

• Test breeder fission and nuclear fusion

• Opponents of nuclear power

• Fund rapid development of energy efficient and renewable energy resources

Three Big Ideas

1. A key factor to consider in evaluating the usefulness of any energy resource is its net energy yield.

2. Conventional oil, natural gas, and coal are plentiful and have moderate to high net energy yields, but using any fossil fuel, especially coal, has a high environmental impact.

Three Big Ideas

3. Nuclear power has a low environmental impact and a very low accident risk, but high costs, a low net energy yield, long-lived radioactive wastes, and the potential for spreading nuclear weapons technology have limited its use.

Documents

MILLER/SPOOLMAN LIVING IN THE ENVIRONMENT€¦ · Coal liquefaction 1.4 Oil shale 1.2 . Energy Resources With Low/Negative Net Energy Yields Need Marketplace Help •Cannot compete