17 TH 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

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

Net Energy Ratios Fig. 15-3, p. 373

Fig. 15-3a, p. 373 Space Heating Passive solar5.8 Natural gas4.9 Oil4.5 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 gas4.9 Gasoline (refined crude oil) 4.1 Biofuel (ethanol)1.9 Coal liquefaction1.4 Oil shale1.2

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

How Long Might Supplies of Conventional Crude Oil Last? 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, Figure 1, Supplement 2

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

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 Figure 6, Supplement 9

Proven and Unproven Reserves of Fossil Fuels in North America Figure 18, Supplement 8

Trade-Offs: Conventional Oil Fig. 15-6, p. 377

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 , p. 379

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 -- CH 4 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 , 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 , 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 SO 2 Large amount of soot CO 2 Trace amounts of Hg and radioactive materials

Stages in Coal Formation over Millions of Years Fig , p. 382

CO 2 Emissions Per Unit of Electrical Energy Produced for Energy Sources Fig , p. 383

World Coal and Natural Gas Consumption, Figure 7, Supplement 9

Coal Consumption in China and the United States, Figure 8, Supplement 9

Coal Deposits in the United States Figure 19, Supplement 8

Trade-Offs: Coal Fig , p. 384

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 , p. 385

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 , p. 387

Fission of Uranium-235 Fig. 2-9b, p. 43

Nuclear fission Uranium-235 Neutron Energy Fission fragment n n n n n n 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 , p. 388

Fuel assemblies Decommissioning of reactor Enrichment of UF 6 Reactor Fuel fabrication (conversion of enriched UF 6 to UO 2 and fabrication of fuel assemblies) (conversion of enriched UF 6 to UO 2 and fabrication of fuel assemblies) Temporary storage of spent fuel assemblies underwater or in dry casks Temporary storage of spent fuel assemblies underwater or in dry casks Conversion of U 3 O 8 to UF 6 Spent fuel reprocessing Uranium-235 as UF 6 Plutonium-239 as PuO 2 Low-level radiation with long half-life Mining uranium ore (U 3 O 8 ) Mining uranium ore (U 3 O 8 ) Geologic disposal of moderate- and high-level radioactive wastes 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 Figure 10, Supplement 9

Nuclear Power Plants in the United States Figure 21, Supplement 8

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

Trade-Offs: Conventional Nuclear Fuel Cycle Fig , p. 389

Trade-Offs: Coal versus Nuclear to Produce Electricity Fig , p. 389

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 , 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 CO 2 emission Nuclear fuel cycle: emits CO 2 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 , 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

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