Nonrenewable Resources : Oil and Natural Gas

Fossil Fuel Reserves 1. Enough coal to last us around 112 years at current rates of production (Could last longer) The largest coal reserves are found in the U.S. (1 st ), Russia (2 nd ), and China (3 rd ). This accounts for about 50% of all proven coal reserves.

Coal Is a Plentiful but Dirty Fuel 1. Coal: solid fossil fuel 2. Mined: by strip or subsurface mining  Mining causes habitat degradation  Coal contains a lot of sulfur compounds; rainwater running through spoilage heaps causes ground water contamination 3. Burned in power plants; generates 42% of the world’s electricity  Inefficient average coal-fired power plants is only about 30% efficient 4. Three largest coal-burning countries  China  United States  Canada

Problems with Abandoned Coal Mines 1. Spoil piles contain a lot of toxic chemicals 2. Rainwater mixes and dissolves chemicals which leach out and can contaminate groundwater, surface water, the soil, etc. Spoil heap of an un-reclaimed mine

Coal Is a Plentiful but Dirty Fuel 1. World’s most abundant fossil fuel  U.S. has 28% of proven reserves 2. 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 20 of the world’s worst polluted cities are in China!---Acid Rain The majority of atmospheric mercury is produced by coal burning power plants

Increasing moisture content Increasing heat and carbon content Peat (not a coal) Lignite (brown coal) Bituminous (soft coal) Anthracite (hard coal) Heat 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 , p. 382 Stages in Coal Formation over Millions of Years

Waste heat Coal bunker Turbine Cooling tower transfers waste heat to atmosphere Generator Cooling loop Stack Pulverizing millCondenserFilter Boiler Toxic ash disposal Science: Coal-Burning Power Plant

Coal Consumption in China & the United States, Figure 8, Supplement 9 Acid rain is primarily caused by burning coal! (A lot of SO 2 is given off)

Coal Deposits in the U.S. Figure 19, Supplement 8

Fig , p. 384 AdvantagesDisadvantages 1. Ample supplies in many countries 1. Severe land disturbance and water pollution 2. Fine particle and toxic mercury emissions threaten human health 2. High net energy yield 3. Emits large amounts of CO 2, SO 2, Mercury, and other pollutants when produced and burned 3. Low cost when environmental costs are not included Advantages and Disadvantages of Using Coal as an Energy Source

The Problem of Coal Ash 1. Types of coal ash:  Ash from burning coal  Ash that contains toxic chemicals as a result of removing toxic pollutants from emissions 2. Highly toxic  Arsenic, cadmium, chromium, lead, mercury  Ash left from burning and from emissions 3. Some used as fertilizer by farmers 4. Most is buried or put in ponds  Leachate can contaminate groundwater

The Clean Coal and Anti-Coal Campaigns 1. Coal companies and energy companies fought  Classifying carbon dioxide as a pollutant  Classifying coal ash as hazardous waste  Air pollution standards for emissions clean coal campaign  But no such thing as clean coal

We Can Convert Coal into Gaseous and Liquid Fuels 1. Coal gasification  Converts solid coal into a gas - Synthetic natural gas (SNG)  Removes sulfur & most other impurities from coal 2. Coal Liquefaction  Converts solid coal into a liquid such as methanol or synthetic gasoline 3. SNG and methanol are Synfuels

Fig , p. 385 AdvantagesDisadvantages 1. Large potential supply in many countries 1. Low to moderate net energy yield 2. Vehicle fuel2. Requires mining 50% more coal with increased land disturbance, water pollution and water use 3. Lower air pollution than coal 3. Higher CO 2 emissions than coal Advantages and Disadvantages of Using Synthetic Fuels

How Does a Nuclear Fission Reactor Work? 1.Controlled nuclear fission reaction in a reactor  Light-water reactors  Very inefficient 2. Fueled by uranium ore & packed as pellets in fuel rods & fuel assemblies  Control rods absorb neutrons 3. Water is the usual coolant 4. Containment shell around the core for protection 5. Water-filled pools or dry casks for storage of radioactive spent fuel rod assemblies

Fig a, p. 387 Small amounts of radioactive gases Uranium fuel input (reactor core) Containment shell Waste heat Control rods Heat exchanger SteamTurbine Generator Hot coolant Useful electrical energy about 25% Hot water output Coolant Moderator Cool water input Waste heat ShieldingPressure vessel Coolant passage WaterCondenser Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Water source (river, lake, ocean)

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

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? 1. Slowest-growing energy source and expected to decline more 2. 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

Storing Spent Radioactive Fuel Rods Presents Risks 1. Fuel rods must be replaced every 3-4 years 2. Cooled in water-filled pool 3. Placed and stored in dry casks 4. Must be stored for thousands of years 5. Vulnerable to terrorist attack

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

Radioactive Wastes Produced by Nuclear Power 1. High-level radioactive wastes  Must be stored safely for 10,000– 240,000 years 2. 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 Yucca Mountain was the proposed site for the storage of nuclear waste

What Do We Do with Worn-Out Nuclear Power Plants? 1. Decommission or retire the power plant 2. Some options  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

Can Nuclear Power Lessen Dependence on Imported Oil & Reduce Global Warming? 1. Nuclear power plants: no CO 2 emission 2. Nuclear fuel cycle: emits CO 2 3. Opposing views on nuclear power –Nuclear power advocates –2007: Oxford Research Group 4. Need high rate of building new plants, plus a storage facility for radioactive wastes

Fig , p. 389 Conventional Nuclear Fuel Cycle Low environmental impact (without accidents) Very low net energy yield and high overall cost AdvantagesDisadvantages Emits 1/6 as much CO 2 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 , p. 389