Energy & Air Pollution potx

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 eco

Energy & Air

Pollution

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, and

prosperity also brings us pollution, impoverishment, and global warming

Our challenge is to maximize the benefits gained from energy

consumption while minimizing the costs incurred

Douglas Foy

A fuming smokestack is the perfect symbol of our national dilemma On

the one hand, it means the jobs and products we need On the other, it

means pollution

American Gas Association ad, 1991

• 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 greatest

in large, sparsely populated states

• Fossil fuels are non-renewable resources with limited life

span and their combustion contributes to global warming

• Alternative energy sources such as solar and wind power

are renewable and hold the promise of a sustainable energy

future

U.S Energy Use

Current 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) Environmental

concerns over air pollution and the potential for global

warming may encourage wider access to alternative energy

sources such as nuclear power and wind or solar energy

Nuclear power accounts for about a fifth of U.S electricity

generation but only 5% of total energy consumption

Alternative energy sources (hydroelectric, wind, solar,

geothermal) generate 5% of U.S energy production but may

expand that share in the decades ahead

Energy use within the U.S varies with population size and

character of energy demand (Fig 2) States with large

populations, large land area (greater distances to travel), and

Figure 1 U.S energy consumption per energy type, 1949 to

1995 Graph courtesy

of the Energy Information Administration.

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 millions

of years under specific physical conditions in a select group of

rocks These conditions make it possible to predict where oil

and gas may be found but also highlight the fact that fossil

fuels are non-renewable resources that will not be replaced

once 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 potentially

longer life span than either oil or gas but it has the unfortunatedistinction of generating more pollution than the other fossil

fuels Furthermore, coal produces more carbon dioxide during

combustion 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 threat

of global warming and the nation's dependence on foreign oil

to advance the nuclear cause Fifty years ago, scientists

working 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 generated

by nuclear power and that number is unlikely to grow because

of concerns about the safety of nuclear reactors and anxietyover how to dispose of highly radioactive waste produced

Figure 2 Distribution

of U.S energy use.

Energy use at home

during power generation Rarely has a technology shown such

early promise only to fall so rapidly from grace

Alternative energy resources (hydroelectric, wind, solar,

biomass, geothermal) generate less than 10% of U.S energy

but have few of the drawbacks of fossil fuels or nuclear power

and hold promise of a sustainable energy future A veritable

chorus of Pollyannas has sung the praises of alternative energy

since the 1970s but their potential remains ambiguous because

of uncertainties over the rate of technological development and

operating costs Some of these renewable energy sources have

greater potential than others with solar energy and wind power

holding the most hope for the future

The industrial air pollution that was once proudly viewed as a

by-product of economic growth is now largely a thing of the

past No longer will thousands of people die during a weekend

of lethal air pollution as they did in London in 1952 Air

pollution is still widespread but its effects are muted, hidden

among reports of greater incidence of asthma and other

respiratory ailments and studies of acid rain downwind from

industrial centers The burning of fossil fuels represents a

major source of air pollutants and cleaner air will therefore be

an indirect by-product of any change in energy production in

the years ahead

Figure 3 Perry nuclear reactor, 35 miles northwest of Cleveland, Ohio Lake Erie is on the left of the image.

Image courtesy of the Nuclear Regulatory Commission (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 the

end of the chapter that plots gross domestic product

(GDP) per capita vs energy consumption per capita.

Label the points that represent where you think the

eight named nations would plot on the graph.

3 Draw a time line for energy use before you read any

further in this chapter Label the time line to indicate

how energy consumption has changed/will change

from 1850 to 2050 Differentiate between domestic

and industrial energy sources and transportation

energy sources.

Fossil Fuels: Oil & Gas

• Time and a specific temperature range are necessary for thegeneration of oil and gas

• As hydrocarbons become mature they progress from heavyoils to light oils to natural gas

• Hydrocarbons become concentrated in sedimentary rocks

• The volume of the world’s oil reserves is approximately1,070 billion barrels

• The U.S uses 25% of the world’s oil

• Two-thirds of the world’s oil reserves are located in theMiddle East

Fossil fuels form from decayed organic material Oil, coal, and

natural gas are the most common products of this process Oil

and gas form from organic material in microscopic marine

organisms, whereas coal forms from the decayed remains of

land plants Tar (oil) sands and oil shale are less commonforms of fossil fuels and are less widely used because

extraction of oil from these deposits is more expensive thanproducing other forms of fossil fuels

Generation and Production of Oil and Gas

The two principal requirements in the generation of oil and gas

(also known as hydrocarbons - chemical compounds of

carbon and hydrogen) are time and a specific range of

temperature The steps in the process are:

1 Organic-rich sediments are deposited and gradually

buried to greater depths and converted to sedimentary rock(e.g., shale)

2 Chemical reactions occur during burial under conditions

of increasing temperature and pressure The reactions occur

at temperatures of 50 to 100 o C, higher temperatures "boil

off" the hydrocarbons; lower temperatures are not sufficient

to 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

non-renewable resources because they are consumed much

faster than they can be replaced

Oil and gas migrate upward through fractures and pore spaces

in permeable rocks and/or sediments Some hydrocarbons

escape at Earth’s surface through features such as oil seeps

Others collect below the surface in sedimentary rocks when

their path is blocked by low-permeability rocks (Fig 4) Rock

structures such as faults and folds may serve to juxtapose

permeable and impermeable units Oil and gas are trapped in

the permeable rocks and will migrate upward to lie at the

highest elevation in the rock unit

When an oil field is first drilled the oil is driven into the well

by pressures within the rocks This primary recovery will

extract about 25% of the oil Additional oil can be extracted

using enhanced recovery techniques that make it easier for the

oil to enter the well Such techniques may include artificially

fracturing the rock to create passages for oil migration or

pumping wastewaters from drilling operations into nearby

wells to drive the oil toward the producing well

Oil Reserves

Oil and gas are not distributed uniformly within Earth's crust

(Fig 5) Hydrocarbons are initially formed as organic-rich

sediments 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 areas

underlain by igneous or metamorphic rocks such as volcanic

island chains like Japan or Hawaii Even in areas where

sedimentary rocks are present, they must fall within a specific

age range to ensure that the rocks are mature enough to contain

hydrocarbons but not so old that oil and gas would have long

ago escaped

Oil reserves steadily increased since the first commercial oil

well was drilled in Titusville, Pennsylvania, in 1859 but

estimates of global reserves have remained relatively uniform

Figure 4 Oil and gas will migrate through permeable rocks to the highest available elevation Examples

of traps include folds (left), and faults (right).

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 remote

areas of the world, including the seafloor, using an array ofnew methods that utilize satellites and geophysical

instruments to unravel the geology in regions where fewrocks are visible

• Improved technology used by oil companies to extract

greater volumes of oil through enhanced recoverytechniques

• Greater efficiency in energy use as a result of higher fuel

prices 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 driven

112 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 billion

barrels (one barrel is equivalent to 42 gallons) These reserves

would last for nearly 40 years at current global consumption

Figure 5 Locations of

principal North

American oil fields

(left) and other

hydrocarbon

resources (right).

Most oil shales and

oil sands are not

economically viable

now but may play a

more significant role

in energy production

as supplies decrease.

rates The U.S Geological Survey recently issued a more

optimistic estimate that there actually may be double those

reserves left to be discovered with a potential life span until the

end of this century

The U.S uses 25% of the world's oil, much more than any

other 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 from

relatively modest changes in supply and demand will become

much more exaggerated as the available reserves of oil decline

The future success of the U.S economy may rely on the state

of our political relationships with the relatively few nations that

have abundant oil reserves

The majority of the oil and other petroleum products currently

imported into the U.S come from just four nations, Venezuela,

Mexico, Canada, and Saudi Arabia However, as two-thirds of

all the world's oil reserves are located in the Middle East (Fig

6), countries such as Saudi Arabia, Kuwait, Iran, and Iraq may

play an increasingly important role in U.S oil supply in the

Think about it

1 Use the Venn diagram found at the end of the chapter

to compare and contrast the similarities and

differences between the characteristics of oil and coal

resources

continued on next page

Fossil Fuels: Coal

• The carbon content and heat content of coal increase withincreasing maturity

• The volume of ash residue after burning decreases withincreasing coal maturity

• The two principal regions of coal production in the U.S arethe Appalachian basin and the Great Plains

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

• Air pollution, medical expenses, and landfill fees areexternal costs of coal use

Coal, the carbon-rich residue of plants, can be classified by

rank or carbon content Coal matures by increasing rank with

increasing burial pressure (Fig 7)

2 Similar organic-rich source rocks are present in two locations Oil deposits formed in the overlying rocks at the first location but did not form at the second

location Which of the following is the best explanation for 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.

Peat is the least-mature form of coal, containing a large volume

of fibrous plant matter With increasing compaction, water is

driven out and carbon becomes increasingly concentrated Both

carbon content and the amount of heat released during

burning increase with maturity The carbon content ranges

from around 30% in peat to 99% for anthracite The higher the

carbon content, the more heat that is released when the coal is

burned Small amounts of high-carbon coals produce the same

heat as large volumes of low-carbon coal The volume of ash

that remains after burning decreases with increasing rank The

ash must be disposed off in a landfill thus increasing expense

Figure 8 bearing areas of the U.S Image courtesy of Energy Information Administration.

Coal-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 interior

states (Illinois, Indiana, western Kentucky) produce high-rank bituminous coals and anthracite These coals are produced

from 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) produce

lignite 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 Comparison

of sulfur content and

heat content of coals

from principal U.S.

coal-producing

regions Western

coals have less sulfur

and lower heat

content.

Figure 10 Thick

seam of

sub-bituminous coal in the

Powder River basin,

northeast Wyoming.

This seam is 60

meter (200 foot) thick

for much of its length

and is less than 15

meters(50 feet) below

the surface at this

location.

point today where coal production is approximately equal east

and west of the Mississippi River (Fig 11)

Air pollution represents one of the external costs associated

with the combustion of fossil fuels External costs are the price

we pay indirectly - in taxes, health insurance, medical bills,

landfill fees - because of the use of fossil fuels The use of coal

would become less economically attractive if these costs were

applied to the original (internal) cost of coal Electric utilities

account for approximately 90% of all U.S coal consumption

and are the major source of nitrogen dioxide and sulfur

dioxide, two key air pollutants

The most potentially significant external cost of using fossil

fuels is the build up of carbon dioxide in Earth's atmosphere

Scientists predict that fossil fuel emissions will lead to a

warmer "greenhouse" world, initiating a potential cascade of

negative economic repercussions Consequently, future energy

policy may not be concerned with how much fuel is left, but

may instead focus on how to use it without prompting changes

in global climate

Coal Reserves

Over 80% of the world's recoverable coal is found in just seven

nations (Fig 12) The U.S has the greatest reserves,

accounting for 25% of the world's coal, enough to last for 270

years at current consumption rates This suggests that we will

have a plentiful supply of electricity into the distant future but

it is of little help as a replacement fuel for refined oil products

(gasoline) unless we can assume that automobiles of the future

Figure 11 Principal coal reserves of the U.S Lower map shows top-10 states for coal reserves that can be divided between lignite and sub-bituminous coals

in the West, and mainly bituminous coals and anthracite east of the Mississippi River.

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

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

Figure 12 The U.S.

has a quarter of the

world's available coal

reserves and 83% of

all reserves are

divided among just

seven nations.

Think about it

1 Use the Venn diagram found at the close of the chapter to compare and contrast the characteristics of oil and coal resources.

2 Examine the map of U.S coal resources found at the end of the chapter and predict where the five

numbered points on the graph of sulfur content vs.

BTU might plot on the map.

• The potential problems are: U.S reactors are getting old

and there is no currently available site for permanent

nuclear waste disposal

• A potential storage site for nuclear waste is being

investigated at Yucca Mountain, Nevada

• The Yucca Mountain site is isolated, has a dry climate, in

rocks with low porosity and permeability, and is located far

above the groundwater table However, the area around

Yucca Mountain has experienced earthquakes and

volcanism

Approximately 17% of the world’s electricity is generated by

nuclear power but that represents only 5% of the world’s

consumption of energy Clearly there is room for improvement

Current concerns about global warming have caused some

governments to give nuclear energy another look and has

increased optimism within the nuclear power industry

prompting a series of ads that tout nuclear energy as the

environmentally friendly alternative to dirty fossil fuels Most

technologies evolve into increasingly sophisticated and cheaper

forms following their introduction and will continue to grow in

popularity until they are replaced by a better alternative Not so

nuclear power After a meteoric rise, the nuclear power

industry hit a wall in the latter part of the last century as a

result of problems with their own product

Nuclear energy originated in the nuclear weapons programs of

World War II Following the war, control of nuclear research

passed from military to civilian control with the creation of the

Atomic Energy Commission Early plans to use nuclear

weapons for mega-engineering projects (e.g., excavating a

harbor on the coast of Alaska) were dismissed amid concern

over potential radioactive contamination The first commercial

nuclear power plants generated electricity in the late 1950s.

Nuclear power generation increased steadily until the 1970s

and appeared to be on the road to acceptance as fuel costs

increased during the 1973 oil crisis However, the honeymoon

Figure 13 Three Mile Island Unit 1 reactor, Pennsylvania, with Susquehanna River

in background The Unit 2 reactor is nearby but is no longer in use Image courtesy of the Nuclear Regulatory Commission (NRC).

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 former

Soviet Union (now the Ukraine) in 1986 lessened the chancesfor a rebound in nuclear fortunes The accident resulted from

an 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 Cycle

The 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 500

times 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 and

reprecipitated in a concentrated form known as “yellowcake.”

Uranium Enrichment: Additional processing is required

before the uranium is in a form that can be used in a reactor

Natural uranium consists of two isotopes of uranium The bulk

of natural uranium is U238 Only 0.7% of natural uranium is the

isotope U235 that is capable of undergoing fission, the process

by which energy is produced in a nuclear reactor Enrichment

increases the concentration of U235 to approximately 4% of

the uranium mixture by removing much of the U238 isotope

The uranium is formed into pellets that are placed in metal

tubes to form the fuel rods in a reactor fuel assembly

Nuclear Power Generation: Nuclear reactors generate

electricity from heat much the same way coal- or oil-fired

power plants do The heat converts water to steam, steam spins

a turbine, and the spinning turbine generates electricity The

big difference is in how the heat is generated In power plants

using fossil fuels the fuel of choice is simply burned In a

nuclear plant, nuclear fission, the splitting of the nucleus of an

atom, is the heat source Neutrons ejected from the split atom

hit adjacent atoms, causing them to fission Uranium undergoes

nuclear fission in the fuel rods of a nuclear reactor

Neutron-absorbing control rods may be inserted in the reactor to slow

down the rate of the reaction and produce less heat Both fuel

rods and control rods are stored in water that serves to cool the

rods and moderate the nuclear fission reactions The

radioactive material in fuel rods is not sufficiently enriched to

cause a nuclear explosion but a runaway reaction could result

Figure 14 U.S uranium mining and production plants.

Image courtesy of Energy Information Administration.

in overheating of the surrounding water and cause a steamexplosion.

Nuclear Reactors: A typical nuclear power plant in the U.S is

granted a 40-year license for operation but many are taken out

of service (decommissioned) before the end of that time

interval 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 bulk

of their electricity (Fig 16) France generates over quarters of its electricity from 58 nuclear power plants andLithuania generates 77% of its electricity from just two plants

three-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 the

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 Future

There has recently been renewed interest in the use of nuclear

power in some quarters (mainly from advocates in the nuclearindustry) They cite three principal benefits of the use of

nuclear energy:

1 Air pollution and global warming, associated with fossil

fuels, are not produced by nuclear power plants

2 Electricity from nuclear power would reduce the nation's

dependence on foreign oil which is growing increasingly

scarce

3 New reactors have safer standardized reactor designs that

markedly reduce the potential for an accident

However, for nuclear power to become a viable energy

alternative 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 nuclear

waste The nation still has no repository for this waste and

will not have a disposal site until at least 2010

Nuclear Waste

Nuclear 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 attempting

to find a suitable site where it can store nuclear waste safely for

thousands of years The potential site is located below Yucca

Mountain, Nevada (Fig 17), about a one hour drive north of

Las Vegas

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 Mountain

The 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 from

population centers (Las Vegas is ~100 km south)

Nevada (left) Image

courtesy of the Yucca

Mountain Project.

• The vault would be hollowed out of a layer of volcanic tuff,

a resistant igneous rock with very low porosity (spaces

within the rock that may contain water) and low

permeability (the ability of water to flow through the

rock)

• In addition, the site gets ~15 cm (6 inches) of precipitation

a year, most of which evaporates in the desert heat Project

scientists believe that it is unlikely that water could

inundate the disposal facility and transport radioactive

materials into the surrounding environment

• Furthermore, the local groundwater source is 240 meters

(~750 feet) below the site, making it difficult for any leaks

to pass quickly (before detection) to the groundwater

supply

However, some scientists point out that certain geologic

features point toward potential problems in the future:

• Groundwater flow may be accelerated along fractures and

faults that exist in the region, and that evidence points to an

elevated water table (groundwater) in the relatively recent

geologic past (~10,000 years ago)

• Nevada is one of the most seismically active states after

Alaska and California Some have suggested that the threat

of a damaging earthquake is too great to take the risk of

building the disposal facility in Nevada However, although

there have been numerous small earthquakes near the site,

few have been of sufficient magnitude to pose any threat

and a structure could be engineered to withstand the

moderate-size earthquakes that occasionally occur in

southern Nevada

• Geologically recent (<10,000 years) volcanic activity has

also occurred nearby but scientists at Yucca Mountain have

estimated that there is little probability that future activity

will impact the disposal facility

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 generated

in 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 futurepotential is dependent upon the rate of technological

development and operating costs

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

• Biomass, hydropower, and geothermal energy have

drawbacks 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 principal

energy sources currently in use Approximately 80% of the

nation'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 from

air pollution and concerns about global warming Nuclear

power supplies less than 10% of total U.S energy and is

Think about it

Create a concept map that illustrates the issues

surrounding the use of nuclear energy.