Energy & AirPollution

Introduction

Fossil Fuels: Oil & Gas

Fossil Fuels: Coal

Nuclear Energy

Alternative Energy Resources

Air Pollution

Summary

At the heart of modern society lies an economy driven by energy use.Unfortunately, the same energy that brings us comfort, convenience, andprosperity also brings us pollution, impoverishment, and global warming.Our challenge is to maximize the benefits gained from energyconsumption while minimizing the costs incurred.

Douglas Foy

A fuming smokestack is the perfect symbol of our national dilemma. Onthe one hand, it means the jobs and products we need. On the other, itmeans pollution.

American Gas Association ad, 1991

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Introduction• Fossil fuels (oil, gas, coal) makeup most of the energy

consumed in the U.S.• Energy use increases with increasing population, land area,

and industrial activity and energy use per capita is greatestin large, sparsely populated states.

• Fossil fuels are non-renewable resources with limited lifespan and their combustion contributes to global warming.

• Alternative energy sources such as solar and wind powerare renewable and hold the promise of a sustainable energyfuture.

U.S. Energy UseCurrent U.S. energy use is weighted heavily toward fossil fuels(oil, natural gas, and coal) that account for approximately 90%of all energy used in the nation (Fig. 1). Environmentalconcerns over air pollution and the potential for globalwarming may encourage wider access to alternative energysources such as nuclear power and wind or solar energy.Nuclear power accounts for about a fifth of U.S. electricitygeneration but only 5% of total energy consumption.Alternative energy sources (hydroelectric, wind, solar,geothermal) generate 5% of U.S. energy production but mayexpand that share in the decades ahead.

Energy use within the U.S. varies with population size andcharacter of energy demand (Fig. 2). States with largepopulations, large land area (greater distances to travel), and

Figure 1. U.S. energyconsumption perenergy type, 1949 to1995. Graph courtesyof the EnergyInformationAdministration.

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energy-intensive industries (e.g., oil refining, chemicals),typically use the most energy. Large sparsely populated statessuch as Wyoming and Alaska rate highly in energy use perperson because transportation consumes large volumes of fuel.

Fossil fuels form from decayed organic material through aseries of chemical reactions that occur gradually over millionsof years under specific physical conditions in a select group ofrocks. These conditions make it possible to predict where oiland gas may be found but also highlight the fact that fossilfuels are non-renewable resources that will not be replacedonce used. Reserves of oil and natural gas will probably bestretched out for another century but we must face theinevitable conclusion that these finite resources will have to bereplaced with an alternative form of energy in the next 50years. The inevitable decrease in the availability of fossil fuelswill be felt most acutely in transportation because there is noviable inexpensive replacement for the refined petroleumproducts that fuel automobiles and airplanes.

Coal represents an alternative fossil fuel with a potentiallylonger life span than either oil or gas but it has the unfortunatedistinction of generating more pollution than the other fossilfuels. Furthermore, coal produces more carbon dioxide duringcombustion than either oil or gas, but all three have beenfingered as the primary sources of the greenhouse gas that isthe culprit for global warming.

Advocates of a nuclear future have seized the potential threatof global warming and the nation's dependence on foreign oilto advance the nuclear cause. Fifty years ago, scientistsworking in the fledgling U.S. nuclear power industry (Fig. 3)predicted that electricity would be virtually free by the end ofthe century because of the electrical benevolence of nuclearenergy. Today, only 17% of the world’s electricity is generatedby nuclear power and that number is unlikely to grow becauseof concerns about the safety of nuclear reactors and anxietyover how to dispose of highly radioactive waste produced

Figure 2. Distributionof U.S. energy use.Energy use at homeand industry istypically in the form ofelectricity generatedby burning coal.Transportation isalmost exclusivelyfueled by forms ofgasoline refined frompetroleum.

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during power generation. Rarely has a technology shown suchearly promise only to fall so rapidly from grace. Alternative energy resources (hydroelectric, wind, solar,biomass, geothermal) generate less than 10% of U.S. energybut have few of the drawbacks of fossil fuels or nuclear powerand hold promise of a sustainable energy future. A veritablechorus of Pollyannas has sung the praises of alternative energysince the 1970s but their potential remains ambiguous becauseof uncertainties over the rate of technological development andoperating costs. Some of these renewable energy sources havegreater potential than others with solar energy and wind powerholding the most hope for the future. The industrial air pollution that was once proudly viewed as aby-product of economic growth is now largely a thing of thepast. No longer will thousands of people die during a weekendof lethal air pollution as they did in London in 1952. Airpollution is still widespread but its effects are muted, hiddenamong reports of greater incidence of asthma and otherrespiratory ailments and studies of acid rain downwind fromindustrial centers. The burning of fossil fuels represents amajor source of air pollutants and cleaner air will therefore bean indirect by-product of any change in energy production inthe years ahead.

Figure 3. Perrynuclear reactor, 35miles northwest ofCleveland, Ohio.Lake Erie is on theleft of the image.Image courtesy of theNuclear RegulatoryCommission (NRC).

Think about it . . .1. Predict which of the following states consumes the

most energy.a) California b) Illinois c) New York d) Texas

2. Examine the partially completed graph found at theend of the chapter that plots gross domestic product(GDP) per capita vs. energy consumption per capita.Label the points that represent where you think theeight named nations would plot on the graph.

3. Draw a time line for energy use before you read anyfurther in this chapter. Label the time line to indicatehow energy consumption has changed/will changefrom 1850 to 2050. Differentiate between domesticand industrial energy sources and transportationenergy sources.

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Fossil Fuels: Oil & Gas• Time and a specific temperature range are necessary for the

generation of oil and gas.• As hydrocarbons become mature they progress from heavy

oils to light oils to natural gas.• Hydrocarbons become concentrated in sedimentary rocks.• The volume of the world’s oil reserves is approximately

1,070 billion barrels.• The U.S. uses 25% of the world’s oil.• Two-thirds of the world’s oil reserves are located in the

Middle East.

Fossil fuels form from decayed organic material. Oil, coal, andnatural gas are the most common products of this process. Oiland gas form from organic material in microscopic marineorganisms, whereas coal forms from the decayed remains ofland plants. Tar (oil) sands and oil shale are less commonforms of fossil fuels and are less widely used becauseextraction of oil from these deposits is more expensive thanproducing other forms of fossil fuels.

Generation and Production of Oil and GasThe two principal requirements in the generation of oil and gas(also known as hydrocarbons - chemical compounds ofcarbon and hydrogen) are time and a specific range oftemperature. The steps in the process are:

1. Organic-rich sediments are deposited and graduallyburied to greater depths and converted to sedimentary rock(e.g., shale).

2. Chemical reactions occur during burial under conditionsof increasing temperature and pressure. The reactions occurat temperatures of 50 to 100oC, higher temperatures "boiloff" the hydrocarbons; lower temperatures are not sufficientto drive the chemical reactions.

3. The reactions change the organic molecules to hydrocarbonmolecules. With increasing time (millions of years) thehydrocarbons become more mature changing from heavyoils to lighter oils to natural gas. Fossil fuels are considered

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non-renewable resources because they are consumed muchfaster than they can be replaced.

Oil and gas migrate upward through fractures and pore spacesin permeable rocks and/or sediments. Some hydrocarbonsescape at Earth’s surface through features such as oil seeps.Others collect below the surface in sedimentary rocks whentheir path is blocked by low-permeability rocks (Fig. 4). Rockstructures such as faults and folds may serve to juxtaposepermeable and impermeable units. Oil and gas are trapped inthe permeable rocks and will migrate upward to lie at thehighest elevation in the rock unit.

When an oil field is first drilled the oil is driven into the wellby pressures within the rocks. This primary recovery willextract about 25% of the oil. Additional oil can be extractedusing enhanced recovery techniques that make it easier for theoil to enter the well. Such techniques may include artificiallyfracturing the rock to create passages for oil migration orpumping wastewaters from drilling operations into nearbywells to drive the oil toward the producing well.

Oil ReservesOil and gas are not distributed uniformly within Earth's crust(Fig. 5). Hydrocarbons are initially formed as organic-richsediments and the oil and gas subsequently migrate upward,into younger rocks that are also of sedimentary origin.Consequently, oil and gas reserves are generally absent in areasunderlain by igneous or metamorphic rocks such as volcanicisland chains like Japan or Hawaii. Even in areas wheresedimentary rocks are present, they must fall within a specificage range to ensure that the rocks are mature enough to containhydrocarbons but not so old that oil and gas would have longago escaped.

Oil reserves steadily increased since the first commercial oilwell was drilled in Titusville, Pennsylvania, in 1859 butestimates of global reserves have remained relatively uniform

Figure 4. Oil and gaswill migrate throughpermeable rocks tothe highest availableelevation. Examplesof traps include folds(left), and faults(right).

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at around a billion barrels over the last decade. Oil reservesremained stable despite the fact that global population hasdoubled in the last thirty years. Reserves haven't declinedbecause of:

• Exploration of geologic formations in increasingly remoteareas of the world, including the seafloor, using an array ofnew methods that utilize satellites and geophysicalinstruments to unravel the geology in regions where fewrocks are visible.

• Improved technology used by oil companies to extractgreater volumes of oil through enhanced recoverytechniques.

• Greater efficiency in energy use as a result of higher fuelprices and stricter pollution standards that causedmanufacturers to build more energy-efficient appliancesand engines.

Further improvements in energy efficiency will continue todelay the inevitable decline in oil reserves. For example,recently introduced combination gas-electric cars can be driven112 km (70 miles) on a gallon of gas. However, even with thebest management and environmental stewardship we mustanticipate that a world that continues to rely on oil will see thisfinite resource decline toward the second half of this century.

Known world oil reserves are approximately 1,030 billionbarrels (one barrel is equivalent to 42 gallons). These reserveswould last for nearly 40 years at current global consumption

Figure 5. Locations ofprincipal NorthAmerican oil fields(left) and otherhydrocarbonresources (right).Most oil shales andoil sands are noteconomically viablenow but may play amore significant rolein energy productionas supplies decrease.

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rates. The U.S. Geological Survey recently issued a moreoptimistic estimate that there actually may be double thosereserves left to be discovered with a potential life span until theend of this century.

The U.S. uses 25% of the world's oil, much more than anyother nation, and imports over half of the oil it consumes.Consequently we are vulnerable to disruptions in oil supplies.Current fluctuations in gasoline prices that result fromrelatively modest changes in supply and demand will becomemuch more exaggerated as the available reserves of oil decline.The future success of the U.S. economy may rely on the stateof our political relationships with the relatively few nations thathave abundant oil reserves.

The majority of the oil and other petroleum products currentlyimported into the U.S. come from just four nations, Venezuela,Mexico, Canada, and Saudi Arabia. However, as two-thirds ofall the world's oil reserves are located in the Middle East (Fig.6), countries such as Saudi Arabia, Kuwait, Iran, and Iraq mayplay an increasingly important role in U.S. oil supply in thedecades ahead.

Figure 6. Distributionof global oil and gasreserves expressedas a percentage ofglobal reserves. Two-thirds of the world’soil and one-third of allnatural gas reservesare located in theMiddle East. Russiahas 33% of theworld's natural gasand Saudi Arabia has25% of the world's oil.

Think about it . . .1. Use the Venn diagram found at the end of the chapter

to compare and contrast the similarities anddifferences between the characteristics of oil and coalresources.

. . . continued on next page

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Fossil Fuels: Coal• The carbon content and heat content of coal increase with

increasing maturity.• The volume of ash residue after burning decreases with

increasing coal maturity.• The two principal regions of coal production in the U.S. are

the Appalachian basin and the Great Plains.• Sulfur content of coal is lower in the Great Plains and

higher in the Appalachian basin.• Air pollution, medical expenses, and landfill fees are

external costs of coal use.

Coal, the carbon-rich residue of plants, can be classified byrank or carbon content. Coal matures by increasing rank withincreasing burial pressure (Fig. 7).

2. Similar organic-rich source rocks are present in twolocations. Oil deposits formed in the overlying rocks atthe first location but did not form at the secondlocation. Which of the following is the best explanationfor this difference?a) The first location was more deeply buried than the

second.b) The first location was subjected to lower

temperatures than the second.c) The first location contains younger rocks than the

second.d) Rocks at the first location had lower permeability

than rocks at the second site.

Figure 7. Progressionof coal rank (maturity)from carbon-poorpeat to carbon-richanthracite. Therelative proportion ofU.S. coal productionby rank is anthracite2%, bituminous 53%,sub-bituminous 36%,and lignite 9%.

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Peat is the least-mature form of coal, containing a large volumeof fibrous plant matter. With increasing compaction, water isdriven out and carbon becomes increasingly concentrated. Bothcarbon content and the amount of heat released duringburning increase with maturity. The carbon content rangesfrom around 30% in peat to 99% for anthracite. The higher thecarbon content, the more heat that is released when the coal isburned. Small amounts of high-carbon coals produce the sameheat as large volumes of low-carbon coal. The volume of ashthat remains after burning decreases with increasing rank. Theash must be disposed off in a landfill thus increasing expense.

Figure 8. Coal-bearing areas of theU.S. Image courtesy ofEnergy InformationAdministration.

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There are three principal coal-producing regions in the U.S.(Fig. 8). The first two, Appalachian basin states (Ohio,eastern Kentucky, West Virginia, Pennsylvania) and interiorstates (Illinois, Indiana, western Kentucky) produce high-rankbituminous coals and anthracite. These coals are producedfrom both surface and underground mines. Unfortunately,some of the bituminous coals have a high sulfur content (Fig.9) and therefore contribute to air pollution. Given the stringentregulations on pollutants, some companies prefer to use lower-grade sub-bituminous coals to avoid costs associated withinstalling pollution control devices.

Great Plains and Rocky Mountain states (Montana,Wyoming, North Dakota, South Dakota, Colorado) producelignite and sub-bituminous coals from surface mines (Figs. 8,10). These coals may occur in especially thick seams makingthe mining process much less expensive than for undergroundmines. Larger volumes of these lower-grade coals must beburned to generate the same heat as bituminous coal oranthracite. Companies pay more to haul the extra coal but savemoney on production and labor costs. Sub-bituminous coalswere not heavily mined prior to 1970. Subsequent to that datesurface mines have produced more coal than undergroundmines and the western coal production has steadily risen to a

Figure 9. Comparisonof sulfur content andheat content of coalsfrom principal U.S.coal-producingregions. Westerncoals have less sulfurand lower heatcontent.

Figure 10. Thickseam of sub-bituminous coal in thePowder River basin,northeast Wyoming.This seam is 60meter (200 foot) thickfor much of its lengthand is less than 15meters(50 feet) belowthe surface at thislocation.

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point today where coal production is approximately equal eastand west of the Mississippi River (Fig. 11).

Air pollution represents one of the external costs associatedwith the combustion of fossil fuels. External costs are the pricewe pay indirectly - in taxes, health insurance, medical bills,landfill fees - because of the use of fossil fuels. The use of coalwould become less economically attractive if these costs wereapplied to the original (internal) cost of coal. Electric utilitiesaccount for approximately 90% of all U.S. coal consumptionand are the major source of nitrogen dioxide and sulfurdioxide, two key air pollutants.

The most potentially significant external cost of using fossilfuels is the build up of carbon dioxide in Earth's atmosphere.Scientists predict that fossil fuel emissions will lead to awarmer "greenhouse" world, initiating a potential cascade ofnegative economic repercussions. Consequently, future energypolicy may not be concerned with how much fuel is left, butmay instead focus on how to use it without prompting changesin global climate.

Coal ReservesOver 80% of the world's recoverable coal is found in just sevennations (Fig. 12). The U.S. has the greatest reserves,accounting for 25% of the world's coal, enough to last for 270years at current consumption rates. This suggests that we willhave a plentiful supply of electricity into the distant future butit is of little help as a replacement fuel for refined oil products(gasoline) unless we can assume that automobiles of the future

Figure 11. Principalcoal reserves of theU.S. Lower mapshows top-10 statesfor coal reserves thatcan be dividedbetween lignite andsub-bituminous coalsin the West, andmainly bituminouscoals and anthraciteeast of the MississippiRiver.

will run, at least partially, on electricity. Even in this scenario,we are still left with the potential for additional air pollutionand the threat of global warming.

Figure 12. The U.S.has a quarter of theworld's available coalreserves and 83% ofall reserves aredivided among justseven nations.

Think about it . . .1. Use the Venn diagram found at the close of the

chapter to compare and contrast the characteristics ofoil and coal resources.

2. Examine the map of U.S. coal resources found at theend of the chapter and predict where the fivenumbered points on the graph of sulfur content vs.BTU might plot on the map.

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Nuclear Energy• Nuclear reactors generate 17% of the world’s electricity

and 5% of total energy.• Nuclear power has fallen from favor because of accidents

like Three Mile Island (1979) and Chernobyl (1986).• There are over 100 operating nuclear reactors in the U.S.,

approximately a quarter of all nuclear power plantsworldwide.

• The benefits of nuclear energy are: no air pollution, nogreenhouse effect, and a reduction in dependence onforeign oil.

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• The potential problems are: U.S. reactors are getting oldand there is no currently available site for permanentnuclear waste disposal.

• A potential storage site for nuclear waste is beinginvestigated at Yucca Mountain, Nevada.

• The Yucca Mountain site is isolated, has a dry climate, inrocks with low porosity and permeability, and is located farabove the groundwater table. However, the area aroundYucca Mountain has experienced earthquakes andvolcanism.

Approximately 17% of the world’s electricity is generated bynuclear power but that represents only 5% of the world’sconsumption of energy. Clearly there is room for improvement.Current concerns about global warming have caused somegovernments to give nuclear energy another look and hasincreased optimism within the nuclear power industryprompting a series of ads that tout nuclear energy as theenvironmentally friendly alternative to dirty fossil fuels. Mosttechnologies evolve into increasingly sophisticated and cheaperforms following their introduction and will continue to grow inpopularity until they are replaced by a better alternative. Not sonuclear power. After a meteoric rise, the nuclear powerindustry hit a wall in the latter part of the last century as aresult of problems with their own product.

Nuclear energy originated in the nuclear weapons programs ofWorld War II. Following the war, control of nuclear researchpassed from military to civilian control with the creation of theAtomic Energy Commission. Early plans to use nuclearweapons for mega-engineering projects (e.g., excavating aharbor on the coast of Alaska) were dismissed amid concernover potential radioactive contamination. The first commercialnuclear power plants generated electricity in the late 1950s.Nuclear power generation increased steadily until the 1970sand appeared to be on the road to acceptance as fuel costsincreased during the 1973 oil crisis. However, the honeymoon

Figure 13. Three MileIsland Unit 1 reactor,Pennsylvania, withSusquehanna Riverin background. TheUnit 2 reactor isnearby but is nolonger in use. Imagecourtesy of the NuclearRegulatory Commission(NRC).

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ended amidst with construction costs and a widely reportedaccident at the Three Mile Island Unit 2 reactor (1979), nearHarrisburg, Pennsylvania (Fig. 13). Furthermore, the demandfor energy decreased as energy conservation and efficiencygained popularity.

A dangerous nuclear accident at Chernobyl in the formerSoviet Union (now the Ukraine) in 1986 lessened the chancesfor a rebound in nuclear fortunes. The accident resulted froman unauthorized experiment by operators who were testing thecapabilities of the reactor. Two explosions blew the top of thepower plant. The reactor did not have a containment vessel(unlike U.S. reactors) allowing the escape of radioactive debrisinto the atmosphere. The accident was revealed when Swedendetected an increase in wind-borne radiation. As a result of theaccident, over 200,000 people had to be moved from the areasurrounding the damaged reactor; 31 workers and emergencypersonnel died immediately after accident and an unknownnumber of people died later because of exposure to lesserlevels of radioactivity. A concrete "sarcophagus" was builtover the damaged reactor in an unsuccessful effort to containany further leaks.

The nuclear industry argues that improved reactor design andthe absence of airborne pollutants associated with fossil fuelsmake nuclear power an ideal source for future energy.

The Nuclear Fuel CycleThe nuclear fuel cycle represents the series of steps that beginwith the mining of uranium, continue through the generation ofelectricity, and end with the disposal of nuclear waste.

Uranium Mining and Milling: Uranium is approximately 500times more abundant in Earth’s crust than gold. The top-fivesources of uranium are Canada (12,029 tonnes, 34% of worldproduction), Australia, Niger, Namibia, and U.S. (Fig. 14).Over half of uranium is produced from open-pit mines. Theoriginal uranium ore contains 0.1 to 1% uranium. Uranium isremoved from ore by milling to produce a refined ore thatcontains approximately 60% uranium. During the millingprocess the uranium is dissolved from the ore andreprecipitated in a concentrated form known as “yellowcake.”

Uranium Enrichment: Additional processing is requiredbefore the uranium is in a form that can be used in a reactor.

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Natural uranium consists of two isotopes of uranium. The bulkof natural uranium is U238. Only 0.7% of natural uranium is theisotope U235 that is capable of undergoing fission, the processby which energy is produced in a nuclear reactor. Enrichmentincreases the concentration of U235 to approximately 4% ofthe uranium mixture by removing much of the U238 isotope.The uranium is formed into pellets that are placed in metaltubes to form the fuel rods in a reactor fuel assembly.

Nuclear Power Generation: Nuclear reactors generateelectricity from heat much the same way coal- or oil-firedpower plants do. The heat converts water to steam, steam spinsa turbine, and the spinning turbine generates electricity. Thebig difference is in how the heat is generated. In power plantsusing fossil fuels the fuel of choice is simply burned. In anuclear plant, nuclear fission, the splitting of the nucleus of anatom, is the heat source. Neutrons ejected from the split atomhit adjacent atoms, causing them to fission. Uranium undergoesnuclear fission in the fuel rods of a nuclear reactor. Neutron-absorbing control rods may be inserted in the reactor to slowdown the rate of the reaction and produce less heat. Both fuelrods and control rods are stored in water that serves to cool therods and moderate the nuclear fission reactions. Theradioactive material in fuel rods is not sufficiently enriched tocause a nuclear explosion but a runaway reaction could result

Figure 14. U.S.uranium mining andproduction plants.Image courtesy ofEnergy InformationAdministration.

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in overheating of the surrounding water and cause a steamexplosion.

Nuclear Reactors: A typical nuclear power plant in the U.S. isgranted a 40-year license for operation but many are taken outof service (decommissioned) before the end of that timeinterval. The oldest currently operating nuclear reactors in theU.S. started up in 1969. There are over 100 nuclear powerplants operating in the U.S. (Fig. 15; 104 as of November,1999) but no new plants have been ordered in the last 20 years.Consequently, as the current plants are decommissioned thetotal number of operating nuclear plants will inevitably decline.

Some nations rely heavily on nuclear power to supply the bulkof their electricity (Fig. 16). France generates over three-quarters of its electricity from 58 nuclear power plants andLithuania generates 77% of its electricity from just two plants.In contrast, the U.S. has 104 nuclear reactors that producemuch more electricity than France (96,977 megawatts vs.61,723 megawatts). However, this represents a smaller

Figure 15. Map of thedistribution of U.S.nuclear reactors.Image courtesy of theNuclear RegulatoryCommission (NRC).

Figure 16. Graph ofproportion ofelectricity fromnuclear power forFrance (58 reactors),Belgium (7), Sweden(12), Japan (52), andU.S. (104). There are428 nuclear powerplants worldwide(1999).

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proportion (19%) of national electricity production than severalother nations. Europe is home to more nuclear reactors thanany other continent (173), and Africa and South America haveonly 5 between them.

Nuclear Energy and the FutureThere has recently been renewed interest in the use of nuclearpower in some quarters (mainly from advocates in the nuclearindustry). They cite three principal benefits of the use ofnuclear energy:

1. Air pollution and global warming, associated with fossilfuels, are not produced by nuclear power plants.

2. Electricity from nuclear power would reduce the nation'sdependence on foreign oil which is growing increasinglyscarce.

3. New reactors have safer standardized reactor designs thatmarkedly reduce the potential for an accident.

However, for nuclear power to become a viable energyalternative in the immediate future it must first deal with thefollowing issues:

1. Many existing nuclear power plants are entering old ageand will have to be decommissioned, reducing the energy-production capacity in the U.S.

2. More nuclear power plants mean more high-level nuclearwaste. The nation still has no repository for this waste andwill not have a disposal site until at least 2010.

Nuclear WasteNuclear waste comes in a variety of forms, each with differentstorage requirements but it is the disposal of high-level nuclearwaste that presents the greatest challenge for the future.Although high-level radioactive waste (e.g. used fuel rods)composes a relatively small volume of all nuclear waste itrepresents nearly all (95%) of the radioactivity nuclear wastesand may remain dangerous for over 10,000 years. Like severalother nations that rely on nuclear energy, the U.S. is attemptingto find a suitable site where it can store nuclear waste safely forthousands of years. The potential site is located below YuccaMountain, Nevada (Fig. 17), about a one hour drive north ofLas Vegas.

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The Department of Energy (DOE) initially identified ninepotential nuclear dump sites but later shortened the list to three(Fig. 17; Hanford, Washington; Deaf Smith County, Texas;Yucca Mountain, Nevada). The DOE hoped to investigate thegeology of each site thoroughly to determine which would bethe safest repository for the dangerous waste. However, inDecember 1987, Congress saw a chance to save some moneyand directed DOE to study just the Yucca Mountain site.Nevada, which has no nuclear power plants, has fought vainlyagainst hosting the site.

Not only must a high-level nuclear waste disposal facility besafe from accidental entry and sabotage, potentially for a fewhundred thousand years, it must also be safe from geologichazards that may release the radioactive materials. The idealsite would be geologically stable to ensure that groundwatercould not infiltrate through the waste, and neither earthquakesnor volcanic eruptions would rupture the containment structure.

Geologic Setting of Yucca MountainThe waste would be stored in sealed containers in anunderground vault approximately 300 m (1,000 feet) below thesurface (Fig. 18). The site at Yucca Mountain is favorable forwaste disposal because:

• It is located in the desert of southern Nevada far frompopulation centers (Las Vegas is ~100 km south).

Figure 17. Threeproposed sites for apossible high-levelnuclear wastedisposal facility wereconsidered (mapright) beforeCongress chose tolocate the site belowYucca Mountain,Nevada (left). Imagecourtesy of the YuccaMountain Project.

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• The vault would be hollowed out of a layer of volcanic tuff,a resistant igneous rock with very low porosity (spaceswithin the rock that may contain water) and lowpermeability (the ability of water to flow through therock).

• In addition, the site gets ~15 cm (6 inches) of precipitationa year, most of which evaporates in the desert heat. Projectscientists believe that it is unlikely that water couldinundate the disposal facility and transport radioactivematerials into the surrounding environment.

• Furthermore, the local groundwater source is 240 meters(~750 feet) below the site, making it difficult for any leaksto pass quickly (before detection) to the groundwatersupply.

However, some scientists point out that certain geologicfeatures point toward potential problems in the future:

• Groundwater flow may be accelerated along fractures andfaults that exist in the region, and that evidence points to anelevated water table (groundwater) in the relatively recentgeologic past (~10,000 years ago).

• Nevada is one of the most seismically active states afterAlaska and California. Some have suggested that the threatof a damaging earthquake is too great to take the risk ofbuilding the disposal facility in Nevada. However, althoughthere have been numerous small earthquakes near the site,few have been of sufficient magnitude to pose any threatand a structure could be engineered to withstand themoderate-size earthquakes that occasionally occur insouthern Nevada.

• Geologically recent (<10,000 years) volcanic activity hasalso occurred nearby but scientists at Yucca Mountain haveestimated that there is little probability that future activitywill impact the disposal facility.

Figure 18.Approximate positionof the nuclear wasterepository inimpermeable volcanictuff rocks belowYucca Mountain,Nevada.

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The original opening date for the high-level nuclear wasterepository was 1998 but was subsequently changed to 2003 andthen to 2010, reflecting the controversy the site has generatedin Nevada and nationwide. The development of such a site isessential for the permanent disposal of the nuclear waste thathas already been generated by nuclear power plants. Without aworking disposal facility, the long-term viability of nuclearpower in the U.S. is in jeopardy.

Alternative Energy Resources• Renewable energy is environmentally friendly but its future

potential is dependent upon the rate of technologicaldevelopment and operating costs.

• The potential for the use of renewable energy varies withlocation as landscape, climate, and geology.

• Biomass, hydropower, and geothermal energy havedrawbacks that make it unlikely that they will increase theirshare of U.S. energy significantly in the future.

• Passive solar energy requires that structures be oriented toreceive light and heat from sunlight and active solar energyconverts solar radiation to electricity.

• Wind energy accounts for 0.5% of all U.S. energy butcould generate up to 20%.

Future energy must come from one of the three principalenergy sources currently in use. Approximately 80% of thenation's current energy needs are supplied by fossil fuels (oil,gas, coal) that carry with them the threat of potential energyshortages as well as associated environmental degradation fromair pollution and concerns about global warming. Nuclearpower supplies less than 10% of total U.S. energy and is

Think about it . . .Create a concept map that illustrates the issuessurrounding the use of nuclear energy.

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unlikely to undergo a resurgence any time soon in the face ofpublic skepticism over the possibility of a nuclear future.Renewable energy (hydropower, wind, solar, biomass,geothermal), therefore, remains the sole potential energysource that will ensure minimal environmental harm and alsohas the potential to free us from reliance on foreign suppliers.Technological improvements and economies of scale mayreduce costs sufficiently to increase the proportion of U.S.energy from renewable sources from its current level (Fig. 19;less than 10%) to at least 30% of total energy use.

Controls on Renewable EnergyUnlike fossil fuels, renewable energy must often be usedrelatively close to where it is generated. Transmission linesmay conduct electricity up to hundreds of kilometers from itsoriginal source but are not efficient enough to transmit it cross-country to any location where it is needed. Hydroelectric andgeothermal power are more common in western states becauseof the underlying geology. Stream gradients are relatively steepand thousands of acres of undeveloped lands were available tobe flooded behind massive dams. In addition, recent volcanismis feed by shallow magma chambers that provide a ready heatsource for circulating groundwater. Climate conditions alsofavor greater development of solar and wind power west of the

Mississippi River in regions characterized by high insolation

Figure 19. Proportionof U.S. energygenerated byrenewable energy vs.fossil fuels andnuclear power.

Figure 20. The mostwidely usedrenewable energysources are biomass(e.g., burning wood)and hydroelectricpower.

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(incoming solar radiation) and/or high consistent wind speeds.Biomass (wood products) represents the only form ofrenewable energy that can be readily transported in its primarystate. The burning of wood (biomass) and hydropowerrepresent the great majority of current renewable energy use inthe U.S. (Fig. 20).

Two of the principal restrictions in the development ofalternative energy sources are the demand for land and therelative cost (Figs. 21, 22). Fossil fuels require a relativelysmall land area to be produced and refined. In contrast,hydroelectric power requires the flooding of large areas toensure a sufficient supply of water. Biomass (burning oforganic material such as fast-growing varieties of wood likewillow) demands the greatest land area to generate a givenamount of electricity (Fig. 21). It is unlikely that sufficient landarea can be converted to forests to produce the wood necessaryto replace fossil fuels in power plants. Most land is alreadydedicated to other uses (agriculture, buildings) or does not havethe climate required to develop forests.

The main constraint on use of renewable energy sources todayis cost (Fig. 22). As long as renewable energy is moreexpensive than conventional fuels it will not be widely used.Some forms of renewable energy (wind, hydroelectric) arecompetitive with the cost of building nuclear power plants butonly hydroelectric power compares favorably with the mainsource of electricity in the U.S., coal.

Figure 21. Area ofland necessary togenerate 1 billionkilowatts of electricityper year for differentenergy sources.Renewable sourcesrequire more land permeasure of electricity.

Figure 22. Relativecost to generate onekilowatt-hour ofelectricity. Currentcosts of solar energyare approximately 4times those ofelectricity generatedat a coal-fired powerplant.

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Hydropower production in the U.S. is a close second to theworld's leader (Canada). Energy is generated when waterdropping from higher to lower elevations is used to driveturbines that rotate generators to produce electricity. Earlysettlers used water wheels alongside rapidly flowing streams.Today, power is generated by the 200-meter (660 foot) drop ofwater within giant dams on western rivers such as the Colorado(Fig. 23) and Columbia.

Although construction of the earliest western dams was viewedas a blessing in the parched drylands of Arizona and California,later projects met with increasing opposition because of thedramatic changes in the physical environment both upstream(drowned lands, siltation of reservoirs) and downstream(altered stream channels, uniform [unnatural] streamflow).Many of the best potential dam sites are now in nationalparklands or have competition for land use from farming andrecreation interests. It is therefore considered unlikely that anynew large dams will be built in the U.S. but mini-hydroprojects that serve a relatively small population with minimalenvironmental disruption may become increasingly popular.

Geothermal power in its most dramatic form uses heat fromsources of underground steam or hot water (hydrothermalresources) to generate steam used to drive turbines and thusgenerate electricity (Figs. 23, 24). Used waters are recycledback underground to recharge the geothermal reservoir andcontinue the process. Groundwater is heated when it percolatesto sufficient depths to be warmed by Earth's geothermalgradient (~25oC/km) or comes in contact with hot rocks near amagma chamber. Geothermal power plants are found in several

Figure 23. Left:Hoover Dam on theColorado River withLake Mead in thebackground. Right:The Geysers, ageothermal systemnear Calistoga,California. Image byDavid Parsons. Imagecourtesy of Dept. ofEnergy NationalRenewable EnergyLaboratory.

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western states (e.g., California, Nevada, Utah, and Hawaii) andproduce electricity at rates of 5 to 8 cents per kilowatt-hour.Although it has potential for growth, geothermal power isunlikely to take a large share of the U.S. energy marketbecause it is restricted by location to sites in sparsely populatedareas of the West.

Solar and wind energy represent the greatest potential fortechnological advances and increasing energy productionamong renewable energy sources.

Solar EnergySolar energy accounts for approximately 1% of all U.S. energyuse. Passive solar energy refers to using the heat from sunlightto warm buildings (Fig. 25) and was first used in Greek homesover 1,500 years ago. It is estimated that sunlight could be usedto supply up to 90% of home heat, depending upon location.

Figure 25. Modernhouse with passivesolar design, nearDenver, Colorado.House combinespassive (south-facingwindows) and activesolar technologies.Image by DaveParsons. Imagecourtesy of Departmentof Energy NationalRenewable EnergyLaboratory.

Figure 24.Geothermal energysystems exploithydrothermalresources. Heat isextracted from hotgroundwater and thecool wastewaters arereturned to thehydrothermal system.

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Passive solar energy has greater potential in the sunny desertSouthwest than the overcast Pacific Northwest. The use ofpassive solar energy can be readily incorporated into theconstruction of new homes that can be built with windowsfacing south to receive maximum insolation. Unfortunately,such techniques are less useful in older homes.

Active (direct) solar energy can be used in two forms. Wateror oil may be heated in solar collectors that use mirrors to focusthe sunlight onto the liquid (Fig. 26). The hot liquid is thenused for heating. In contrast, photovoltaic cells convertsunlight directly to electricity (Fig. 27).

Solar energy still has some hurdles to overcome before it canbe used extensively. At present some solar energy systems aretoo inefficient for widespread use. For example, when coal isburned approximately half the heat generated can be convertedto electricity. Current models of photovoltaic cells convert lessthan 10% of sunlight into electricity. Some developing nationsare at the forefront of solar energy because it may be moreeconomical to use photovoltaic cells to generate electricity inremote locations instead of having to build transmission lines

Figure 26. Solar One,California; the towerin center of image is a10-megawatt solarreceiver. Image bySandia NationalLaboratories, courtesyof Department ofEnergy NationalRenewable EnergyLaboratory(DOE/NREL).

Figure 27. Left:Woman in India usesa photovoltaic-powered pump tocollect water. Imageby Harin Ullal. Right:Homes in a ruralBrazilian village usephotovoltaic cells toprovide light. Image byRoger Taylor. Imagescourtesy of Departmentof Energy NationalRenewable EnergyLaboratory.

to conduct electricity large distances to serve relatively smallpopulations (Fig. 27).

Wind PowerWind power accounts for approximately 0.5% of U.S.electricity (Fig. 28). Technological advances are making windpower increasingly competitive with costs ranging from 1 to 10times those of fossil fuels. Suitable wind velocities (over 20km/hr) are consistently present over about 13% of the U.S. andestimates suggest wind power could generate as much as 20%of U.S. energy in the future.

The areas with the greatest potential for wind power aredetermined by the patterns of prevailing winds that consistentlyexhibit sufficient velocity and reliability only over the GreatPlains states. Unfortunately, these states are hundreds of milesfrom population centers were the power would be needed. Newor improved transmission lines necessary to get the power tosuitable markets are unlikely to be built until it can bedemonstrated that the region can generate sufficient energy.However, there is little incentive to invest in huge wind farmswithout such a delivery system in place. The great majority ofU.S. wind turbines are located in California (Fig. 28).

Figure 28. A series of100 kW wind turbinesnear Altamont Pass,California. Image byEd Linton. Imagecourtesy of Departmentof Energy NationalRenewable EnergyLaboratory(DOE/NREL).

Think about it . . .1. Use the Venn diagram found at the end of the chapter

to compare and contrast the characteristics of nuclearenergy and renewable energy resources.

2. The graph located at chapter end compares projectedplots of the generation of wind energy vs. time (1985-2025) with nuclear energy capacity vs. time (1960-2000). Make some predictions on the future of windenergy using the evolution of nuclear power as amodel.

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Air Pollution• Toxic air pollution killed thousands in the relatively recent

past.• Industrial emissions are recorded annually by the EPA's

Toxic Release Inventory.• The concentrations and emissions of six criteria pollutants

are regularly measured against a set of national standards.• National air quality is improving despite increases in

population, transportation, and economic growth.• In addition to various health effects, air pollution also

causes acid rain and can reduce visibility.

Air quality diminished in big cities following the IndustrialRevolution and declined further as the popularity of theautomobile increased during the last century. Air pollution atEarth's surface is at least partially dependent upon weatherconditions. The combination of tall smokestacks and steadyprevailing winds will generally ensure that emissions aredispersed and diluted.

Air temperature decreases upward under normal atmosphericconditions and emissions rise upward. However, atmosphericconditions may sometimes be reversed creating a situationwhere cold air is trapped below warm air, creating atemperature inversion (Fig. 29). Under such conditions thecold air will remain stagnant, unable to rise, until dispersed bychanging weather conditions. Dense concentrations ofpollutants trapped close to the ground surface may create lethalair pollution similar to that which caused 5,000 deaths in asingle weekend in London, 1952. Twenty people died andhundreds became ill as a result of toxic air pollution inDonora, Pennsylvania, in October 1948. Emissions from azinc wire plant were trapped close to ground level by atemperature inversion. Most of those affected were elderly.

Figure 29. Normalatmosphericconditions (left) andconditionsresponsible for atemperature inversion(right). A temperatureinversion occurswhen warm air liesabove cold air,preventing thedispersion ofpollutants.

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Criteria PollutantsNational Ambient Air Quality Standards have been determinedfor only seven pollutants; particulates, sulfur dioxide, carbonmonoxide, nitrogen oxides, lead, hydrocarbons, andphotochemical oxidants (ozone). The EPA recognizes sixcommon "criteria" pollutants:

Criteria Pollutants SourceCarbon monoxide Auto emissionsNitrogen dioxide Auto emissions, electric utilitiesSulfur dioxide Electric utilities, industryParticulates Various (e.g., electric utilities, wood stoves)Ozone NOx + volatile organic compounds + sunlightLead Leaded gasoline, lead smelters

Concentrations of criteria pollutants measured in comparison toNational Ambient Air Quality Standards (NAAQS). The sixcriteria pollutants have decreased in concentration nationwideover the last few decades (Fig. 30), and the volume of

emissions of these pollutants has also declined. However, onerelated group of pollutants, nitrogen oxides, has shown a slightincrease in emissions over the last decade. Recent airregulations are aimed at reducing this last holdout.

Concentrations are linked to the direct emissions of pollutantsor associated gases (e.g., volatile organic compounds, nitrogenoxides). The bulk of U.S. air pollution comes from thecombustion of fossil fuels and industrial processes (Fig. 31).These activities are concentrated in urban areas where millionsof people live in close proximity and devour prodigiousamounts of energy. Most emissions have decreased despite

Figure 30. Trends inemissions of sulfurdioxide (blue),nitrogen oxides(green), and volatileorganic compounds(red) from 1900 to1997. Original graphfrom U.S. EPA NationalAir Quality andEmissions TrendsReport, 1997.

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economic growth and increases in population andtransportation but some locations still are above NAAQS forindividual pollutants or groups of pollutants. The U.S. EPAestimates that ~80 million people live in counties that exceedone or more air quality standards.

National efforts to reduce air pollution initially centered onimproving automobile fuel efficiency standards (greaterdistance on fewer gallons of gas) or modifying gasolinecomposition (unleaded gas). Mass transit systems have beenadded in densely populated cities in an effort to get people outof their cars and into buses or trains. These steps were able toreduce emissions of almost all major pollutants butimprovements have recently slowed as more fuel-efficient carshave been overtaken in popularity by minivans and sportsutility vehicles that have lower fuel-efficiency standards (27.5vs. 20.5 miles per gallon).

Criteria Pollutant Health EffectsCarbon monoxide Reduces oxygen availabilityNitrogen dioxide Respiratory illnessessulfur dioxide Respiratory illnesses, cardiovascular diseaseParticulates Respiratory illnessesOzone Respiratory illnessesLead Anemia, kidney disease, neurological problems

Figure 31. Statescontaining top-10sources of each ofthe criteria pollutantswith a listing of thetypes of sources thatgenerate each type ofpollutant. Informationfrom U.S. EPA'sAirsdata website.

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Although some extreme air pollution events, like those inLondon in 1952, can be directly linked to severe illness ordeath, the health effects associated with less-profound pollutionevents are more ambiguous. Health researchers point to a 56%increase in asthma cases for U.S. residents aged under 18 from1982 to 1991 and suggest there is a correlation betweenpollution levels and illness and mortality rates.

In addition to health effects, air pollution can also result in acidrain and decreased visibility. Acid rain is precipitateddownwind from areas with sulfur dioxide and nitrogen oxideemissions. Acid rains leach nutrients from soils, damageforests, and may cause the acidification of lakes. Recent datahave highlighted decreasing sulfate levels (less acid rain)because of decreasing emissions of contributing pollutants. Airpollutants absorb and scatter light to create a haze that limitsvisibility (Fig. 32).

Summary1. What is the source for the majority of energy used in the

U.S.?Fossil fuels account for the bulk of U.S. energy use. Coal,natural gas, and petroleum are burned to generate electricityand refined petroleum products (e.g., gasoline) are used intransportation. Nuclear energy and alternative (renewable)energy sources (hydroelectric power, biomass) account for the

Figure 32. Good (left)and poor (right)visibility at the GrandCanyon, Arizona, asa result of airpollution. From anoriginal series of 15slides at the GrandCanyon VisibilityTransport Commission.

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remainder of electricity generation and approximately 10% ofall U.S. energy consumption.

2. What factors influence energy use in different locations?States with large populations, large land area (greater distancesto travel), and energy-intensive industries (e.g. oil refining,chemicals), typically use the most energy. Texas is the mostenergy-hungry state because it combines all three of the abovecomponents. States such as Wyoming and Alaska rate highly inenergy use per person because gas consumption is high in theselarge, sparsely populated states. The U.S. uses more energythan any other nation because it also combines a largepopulation (third in the world) with a large land area, and anextensive industrial base.

3. How do fossil fuels form?Fossil fuels form from decayed organic material. Oil, coal andnatural gas are the most common products of this process. Oiland gas form from organic material in microscopic marineorganisms, whereas coal forms from the solid resins and waxesthat characterize land plants. Tar sands and oil shale are lesscommon and are less widely used because extraction of oilfrom these deposits is more expensive than producing the otherforms of fossil fuels.

4. How are oil and gas deposits formed?The two principal requirements in the generation of oil and gasare time and a specific range of temperature. The firstrequirement is an organic-rich source of sediments that areconverted to sedimentary rock. Next, chemical reactions occurduring burial under conditions of increasing temperature andpressure. The reactions occur at temperatures of 50 to 100oC.The reactions change the organic molecules to hydrocarbonmolecules. With increasing time the hydrocarbons becomemore mature changing from heavy oils to lighter oils andfinally, to natural gas. Fossil fuels are considered non-renewable resources because it is not possible to replenishconsumed reserves at geological rates of formation.Commercial hydrocarbon deposits are not found in relativelyold (Precambrian) rocks because these rocks have been aroundfor too long and organic remains would long ago have beenconverted to gas and have escaped from the rocks. Likewise,deeply buried rocks have typically undergone temperatures thatare too high to allow hydrocarbons to remain.

5. Where are the world's oil and gas deposits located?

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Global oil reserves are made up of over 1,000 billion barrels ofoil, approximately two-thirds of which is present in countriesof the Middle East (e.g., Saudi Arabia, Iran, Iraq, Kuwait).Major gas deposits are found in the same nations as well asRussia. Nations with the largest oil reserves typically userelatively little oil; in contrast, countries that use a lot of oil(e.g., U.S., Japan, Germany) may have relatively small oilreserves.

6. How is coal formed?The two principal requirements in the generation of coal aretime and a carbon-rich organic source made up of the solidresins and waxes of plants. With increasing burial, water isexpelled from the organic material and carbon contentincreases.

7. What is coal rank and how does it vary?Coal rank is a measure of the carbon content. Rank increasesfrom a minimum of 30% carbon content for peat to a maximumof 99% or more for anthracite. Burned coal releases more heatwith increasing rank and less ash remains followingcombustion. In order of increasing rank, coal type varies asfollows; peat, lignite, sub-bituminous coal, bituminous coal,and anthracite. Sub-bituminous and bituminous coals are themost common coal types.

8. What other properties of coal are important?The sulfur content of coal is a key factor in determining whattype of coal is used to generate electricity. High-sulfurbituminous coals contribute to air pollution but yield more heatper ton of coal than low sulfur sub-bituminous coal. Utilitycompanies must balance the cost of guarding against pollutionwith the extra cost of transporting more low-grade coals thatgenerate more waste (ash) following combustion. Air pollutionrepresents an external cost associated with the combustion offossil fuels. The use of coal would become less economicallyattractive if these costs were applied to the original (internal)cost of coal. Scientists predict that fossil fuel emissions willlead to a warmer "greenhouse" world, initiating a potentialcascade of negative economic repercussions. Consequently,future energy policy may not be concerned with how much fuelis left, but may instead focus on how to use it withoutprompting changes in global climate.

9. How are coal resources distributed?

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The world's coal resources are distributed more evenly than oiland gas resources and favor some of the largest nations. TheU.S. and China contain approximately half of the world's coal.Within the U.S., there are two regions that contain most of thenation's coal. Appalachian basin states (e.g., Ohio, Kentucky,Pennsylvania, West Virginia) produce high-rank bituminouscoals and anthracite. These coals are typically produced fromunderground mines. Great Plains states (Montana, Wyoming,North Dakota, South Dakota, Colorado) produce sub-bituminous coals from relatively inexpensive surface mines.

10. How has technology changed the generation of energy?Fossil fuel use dominated the first half of the century in allsectors of energy consumption. Nuclear power held muchpromise for electricity generation at the mid-century butnuclear accidents have continued to raise public concerns aboutthe safety of nuclear plants. New technologies associated withsolar and wind energy hold hope for the future as they havefew of the drawbacks associated with other energy sources(pollution, safety). However, renewable energy sources will belimited by climate and have little potential for replacingpetroleum as the energy source of choice for transportation.

11. How is nuclear energy generated?Uranium ore contains is a small fraction of the uranium isotope(U235). The radioactive isotope becomes more concentratedfollowing milling and enrichment. The uranium isotopes split,releasing neutrons, when placed in fuel rods in a reactorassembly and the neutrons are absorbed by other U235 isotopes,causing further fission. Splitting of the isotopes also generatesheat that converts water to steam and drives a turbine togenerate electricity.

12. Which nations rely most heavily on nuclear energy?Thirty-three nations generate electricity using nuclear power.The U.S. uses more electricity from nuclear reactors thananyone else (28% of global electricity generated by nuclearpower) but this represents a relatively small proportion of thenation's total electricity use (19%). Some small countriesgenerate the bulk of their electricity with a few nuclear plants(Lithuania, 2 nuclear reactors, 77% of electricity; Belgium 7and 55%; Switzerland 5 and 41%). Some of the world's mostheavily populated nations have either no operating nuclearpower plants (e.g., Indonesia) or very few relative to the size oftheir populations (China has 3; India, 10; Brazil, 1).

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13. What are the advantages to using nuclear power to generateelectricity?

Nuclear advocates typically identify three principal benefits ofthe use of nuclear energy: (1) a reduction in air pollution anddecrease in the potential for global warming associated withfossil fuel use, (2) electricity from nuclear power would reducethe nation's dependence on foreign oil, (3) new reactors havesafer standardized reactor designs that markedly reduce thepotential for an accident.

14. Sounds pretty convincing, why don't utility companiesbuild more nuclear reactors?

Assuming that people could be convinced of the safety ofnuclear reactors - a big “if” at present, there are still two issuesthat must be dealt with before nuclear energy becomes viablein the long term. First, many existing nuclear power plants areapproaching the time when they have to be retired from use(decommissioned) and it will undoubtedly cost companies a lotof money to dismantle these plants in the relatively near futureleaving fewer funds for building new reactors. Second, morenuclear power plants mean more high-level nuclear waste andthere is still nowhere to permanently (100,000's years) store thewaste until it is no longer harmful. And just wait until they starttrucking waste cross-country to Yucca Mountain.

15. Why are they trying to dump nuclear waste under amountain in Nevada?

Locating a dump for highly radioactive waste requires abalance be struck between suitable geologic conditions andcultural and political forces. Nevada's geology and climatemakes it a suitable site for a repository and its relatively smallpopulation makes it politically feasible to site the dump in thestate. Any suitable site must have low-porosity/permeabilityrocks that will protect the waste from groundwater infiltrationand must be remote enough so that people are unlikely toaccidentally expose the material during future development.Ideally, the site would also be far from potential hazards thatmight damage the integrity of the repository. Nevada is lessthan ideal on this score because it has frequent earthquakes(small-moderate) and relatively recent volcanic activity.However, few places are without some form of risk andscientists will analyze the site to determine if the potentialhazards make it an unsound choice.

16. What is renewable energy?

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Renewable energy comes in a variety of forms that remainundiminished with use. It also has the potential to have less ofa negative impact on the environment than fossil fuels ornuclear power. The principal types of renewable energyinclude geothermal, hydroelectric, biomass, solar, and wind.

17. What forms of renewable energy are currently significantcontributors to U.S. energy?

Biomass (burning of wood) and hydroelectric power(electricity generated from dams) account for most of therenewable energy generated in the U.S. today but neither hasmuch potential for growth because there are few rivers left todam and limited area to convert to tree plantations to generatebiomass.

18. What forms of renewable energy hold the greatest promisefor the future?

Solar and wind power. Wind power generation is increasingrapidly worldwide (~20% annually) and photovoltaic cells arecost-effective in locations that are too distant to be supplied bya traditional power grid. Solar power will grow more rapidly asadvancing technology reduces the cost of new photovoltaiccells.

19. What is a temperature inversion?A temperature inversion occurs when cold air lies below warmair. Under normal conditions, the temperature of air decreaseswith increasing altitude. A parcel of warm air will rise throughthe overlying colder air, diluting pollution as it is carried higherin the atmosphere. Pollutants become concentrated below ablanket of warm air when cold air lies immediately above theground surface. The cold air remains trapped near the surfaceuntil changing weather conditions restore normal conditions.

20. What are criteria pollutants?These are the six regulated pollutants that are generallyproducts of the combustion of fossil fuels. The concentration ofparticulates, sulfur dioxide, carbon monoxide, nitrogen dioxide,lead, and ozone are compared to national standards. Locationsthat have elevated concentrations must take steps to reducethem to within the range of the standards.

21. Where does most air pollution come from?The primary source of air pollution is from the combustion offossil fuels. Almost half the energy consumed in the U.S. isfrom petroleum and over half the electricity used comes from

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burning coal. These activities are concentrated in urban areaswhere millions of people live in close proximity and devourprodigious amounts of energy.

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Energy Consumption vs. GDP

GDP is a measure of the total production and consumption ofgoods and services, think of it as the wealth of the nation.Energy consumption is the amount of energy used fortransportation, industry, domestic use, commerce, etc. Notethat both measures used in this exercise are per capita (perperson).

1. Examine the partially completed graph of gross domesticproduct (GDP) per capita vs. energy consumption percapita below. Label the points that represent where youthink the following nations would plot on the graph. Note:China, India, Indonesia, and Brazil are ranked 1, 2, 4, and 5in the world in total population (the U.S. is third).

ChinaJapanIndiaAustralia

IndonesiaSaudi ArabiaBrazilNigeria

2. Can you suggest explanations for the distribution of thenations on the graph?

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Venn Diagram: Oil vs. Coal Resources

Use the Venn diagram, below, to compare and contrast thesimilarities and differences between the characteristics of oiland coal resources. Print this page and write features unique toeither group in the larger areas of the left and right circles; notefeatures that they share in the overlap area in the center of theimage.

Oil Coal

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Sulfur Content vs. Heat Content of U.S. Coal

Examine the map of U.S. coal resources below and predictwhere the five numbered points on the graph of sulfur contentvs. BTU might plot on the map.

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Venn Diagram: Nuclear Energy vs. RenewableEnergy

Use the Venn diagram, below, to compare and contrast thesimilarities and differences between the characteristics ofnuclear energy and renewable energy resources. Print this pageand write features unique to either group in the larger areas ofthe left and right circles; note features that they share in theoverlap area in the center of the image.

Nuclear Energy Renewable Energy

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The Future of Wind Energy

Read the statements below and examine the graph beforeanswering the questions that follow.

Wind energy has grown more rapidly than any other energysource in recent years. Approximately 9.6 gigawatts of energywere generated by wind power in 1998, up from 1 gigawatt in1985. From 1990 to1998, the global annual rate of growth forthe following energy sources was: wind power 22.2%, oil1.8%, nuclear power 0.6%, coal 0.0%.

Nuclear power generated approximately 1 gigawatt of energyin 1960. The use of nuclear energy expanded rapidly in the1970s before becoming less appealing as a result of some well-publicized nuclear accidents between 1979 and 1986. Nuclearenergy generation has leveled off at about 340 gigawatts/yearin recent years.

The graph below compares projected plots of the generation ofwind energy vs. time (1985-2025) with nuclear energy capacityvs. time (1960-2000). The graph projects current trends in thegrowth of wind energy into the future at 10%, 15%, and 20%growth rates.

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1. If we assume a comparable growth rate, approximately howlong will we have to wait until wind energy can producethe same amount of energy as is currently generated bynuclear power?a) 3-6 years c) 21-24 yearsb) 10-12 years d) 35-40 years

2. What factors might cause wind energy generating capacityto level off (wind power growth rate would fall to nearzero) in the future.

3. Will wind energy be as productive as nuclear power?Explain your answer.