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CHAPTER

ENERGY OURCES

1A. Forms of Energy

Energy m ay be described as "the ability to produce heat". Power is the rate of

energy flow from one place or form to another. If no energy f lows across the

boundaries of a given region (an "isolated syste m"), then the total amou nt of

energy inside remains constant, al though many forms of energy may be present, in

varying amo unts. Some form s of energy are listed in Table lA1, and units of

energy are described in Appendix A.

Strictly speaking, energy is not "the ability

to do work", since thermal energy can not be fully converted into work.

lB, Energy Demand

energy uses

Energy is needed in food production, transportation, com mun ication, heating

and cooling buildings, materials processing and manu facturing, and virtually all

aspe cts of modern life. The distribution of energy usage in the United States is

il lustrated in Table lB1.

The historical growth of energy input to the food sys tem and of food energy

consum ed in the United States are show n in Fig. 1Bl. More and more energy input

is needed per calorie of food produced, as we attem pt to grow food on arid lands,

replenish exhausted soil nutrients, etc.

Great am ounts of energy are needed to produce materials, such as lumber,

cem ent, me tals, and plastics , for construc tion and industry. The energy required

to produce one kilogram of various materials is shown in Table 182, along with

the fract ion of the product pr ice which is due to energy cost. As ores become

scarce and depleted, more energy mus t be expended for mining, refining, and pro-

cessing. Recycl ing of scarce mater ials also demands more energy consumption, for

separation, transportation, and processing of materials.

relation to standard of l iving

The gross national product (GNP) per capita is one measu re of the "standard

of l iving" in a coun try. The relationship between the GNP per capita and the

energy consum ption per capita for various countries is show n in Fig. lB2.

1

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2 lA, Formsof Energy

TabZe ZAZ. Some forms of energy (mks units) .

form

definition variables

rest-mass energy = mOc2 m 0 = partic le rest mass (kg) (IAl)

C

= speed of light (m/s)

kinetic energy = mc2-m0c2 m

= relativistic mass of

(IA21

particle (kg)

kinetic energy = mv2/2

m = mass (kg)

(lA3)

(nonrelativistic

case)

V

= speed (m/s)

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lB, EnergyDemand

3

TabZe ZBI. Distribution

of

energy

usage in the United States, 1968.

From Stanford Research Institute,

Patterns of Energy Consumption in the

United States, U.S. Government

Printing Office, Washington, 1972.

industrial

primary metals

chemicals

petro leum refin ing

food and related products

paw

stone, clay, glass, concrete

other

percent

8.7

E::

2.2

2.1

2.1

13.3

41.2

TabZe lB2.

TypicaZ energy contents

of materiak and manufactured pro-

ducts. The actual values of a given

product may vary considerably from

these values,

From The Technology of

efficient Energy Utilization, NATO

Science Conunittee Conference (1973).

Reprints avaiZabZe from Pergamon Press

ratio of

energy energy cost

input to value of

(MJ/kg) product

transportation

gas01 ine

jet fuel

distil late and res

raw materials

other

idual fuel

17.1

;:;

0.3

1.2

25.2

comme rc i a 1

steel

25-30 0.3

copper

25-30

0.05

aluminum 60-270 0.4

magnes i urn

80-100 0.1

glass

(bottles)

30-50 0.3

plastic 10

0.04

paper

25 0.3

inorganic

chemicals

(average)

12

0.2

cement

0.5

1 umber

z

0.1

space heating

air condit ion ing

asphalt and road o i ls

water heating

refrigeration

other

residential

space heating

water heating

refrigeration

cooking

other

6.9

1.8

1.6

1.1

1.1

i i+

11.0

2.9

1.1

1.1

2.4

19.2

Fig. lB1. Annual energy input to United

States food system and annua2 food energy

consumed in the United States for the

;;er;od 1940-1970. 1 ExaJoule (EJ) =

J. 1 EJ/year = 31.7 GW.

Adapted from ENERGY:SOURCES, SE, AND

RODEN HUMAN FFAIRS, by CaroZ E.

Steinhart and John S. Steinhart.

@ 1974 by Wadsworth Publish ing

Company, Inc. Reprinted by permission of

Wadsworth Publish ing Company, Belmont,

California, 94002.

10

0

annual

food energy consumed

a. '

I . I

1940 1950

1960 1970 1980

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4

lC, Energy

Sources

10

Fig. lB2. Gross nationa; product per

capita vs. per-capita energy consumption

rates for various countries, 2977-78

data.

AC = Argentina, AL = Australia,

AU = Austria, BR = Brazil, CA = Canada,

z

CH = China, CZ = CzechosZovakia, EG =

&

East Germany,

FR = France, GR = Greece,

mO

-

HU = Hungary, ID = Indonesia, IN = India, . 1

IR = Iran, IT = Italy, JA = Japan, MX = z

Mexico, PK = Pakistan, SA = South Africa, q

SK = South Korea, SP = Spain, SW=

ik

Sweden, SZ

= Switzerland, TU = Turkey, 0

UK = United Kingdom, UR = USSR, US = USA,

WC= West Germang.

predictions of demand

O-t

The total energy consum ption rate of

the world P, may be wri t ten as the sum of

L

I .1

sz SW

FRWG #

JAAU

A L

, U K EG

/

S K

/

/

CH

/

/

IO

/

P K

IN

/

I

1

1

KW/CAP

10

the energy consum ption rates of the various geographical regions:

pW

= k NkPk

(Watts)

(1Bl)

where Nk is the population of region k and pk is the average per-capita energy

consum ption rate of that region (W/perso n). Both Nk and pk are increasing in

almo st e very region of the world.

Estim ates of the growth of populations and per-capita energy consumption

rates for various geographical regions from 1975 to 2025 are shown in Table 183.

The uncertainty in the 31 TW total is about + 30%. (1 TW = 1012 W ). Similarly,

the world energy deman ds in 2000 and 2050 are estimated to be around 18 TW and 50

TW . World energy product ion rates mus t be great ly expanded to supply these needs,

especially in developing nations.

lC, Energy Sources

power f lows

Renewable energy sources, such as solar, geothermal, biomass, hydroelectric,

wind, w ave, and tidal power, are limited by the usable

power

they provide.

Non-

renewable fossil and nuclear fuels are limited by the total amou nt of energy they

can provide.

About 178,000 TW of solar energy are incident on the earth, of which va rious

amo unts are reflected, reradiated, absorbed by evaporation and flow into wind,

wave s, and photosynthesis (Fig. 1Cl).

Geothermal heat flow and tidal power add

about 35 TW to the balance.

Although the solar and geothermal power flows are

large, the useful fractions are sma ll.

The rate of consum ption of fossil fuels is l imited by availabil ity, transpor-

tation facil it ies, and environmental impa ct. An estima te of the comp lete cycle of

world petroleum production is shown in Fig. lC2. Production will probably decline

after the year 2000.

The restr ict ions of fossi l fuel consumption necessary to

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lC, Energy Sources

5

TabZe lB3. Ccwparison of popuZations,per-capita power demands, and total power

demands in 1975 and estimated for 2025.

Fra R. M. Rotty, %mstraints on

fossi fueZ use", Interactions of Energy and CZimate, Bach, Pankrath and

WiZZioms, editors, ReideZ PubZishing Co.,

1980; and R. M. Rotty, Energy &

881-890 (1979).

populations Nk

pk

total power demands

Nkpk (TW = 1012 W)

REGION

(millions)

1975 2025

( :hg; l ;mal k, l ; l :c,w 1

growth

1975 2025 ratio

--- - ---

N. America

237 315 11.5 15.0 2.72 4.74

W . Europe 305 447

1.70 2.47 i::

E. Europe 81 USS R 359 480

;*Ei 1;*2

1.90 6.54

Japan, Australia, N. Z, 128

320 4:3 6:3 0.55 2.02 2':

Latin America 323 797

0.93 2.8

0.30 2.22 7.4

Africa 370 885 0.16 0.06 0.94 16

China & Indochina 1029 1714 0.61 :$I 0.63 3.43 5.4

South Asia 1170 2665 0.20 0.23 2.80 12

Mid-Eas t 110 353 1.0 2; 0.11 1072 16

--- ---

World average

or total

4031

7976 2.0 3.4

8.20 26.9 3.3

178000 TW solar

radiation incident

62000 TW ref lected

76000 TW heat reradiated imme diately

nuclear fuels

conduction to surface

0.3 TW geothermal heat

convec tion in volcanoes

and hot springs

Fig. ICI.

TerrestriaZ pawer fZaws. PracticaZZy aZZ incident energy is

uZtimateZy reradiated as heat (not show). Based on data from M. K. Eubbert,

"Energy resources of the em?th", Scientific American (September, 19711,

J. M. Weingart, "GZobaZ aspects of sunzight as a major energy source", Energy 5

775-798 (19791, and J. M. Weingart, private conmzunication, 1981.

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6

lD, Solar Energy

247 X 108 tonnes

Year

Fig. lC2. Est imate of world crude oiZ

production rates for the future. From

Energy axd Technology Review, March 1977,

p. 6.

Courtesy 0fLLiVL.

YEAR

Fig. lC3, Necessa ry l imits on fossi Z

fue 2 conswnption,

if

the increases

of

prevent various increases in atmospheric atmospheric CO2 concentration are to be

CO2 concentrations are shown in Fig.

1~3. kept below 50%, 100%, and 200%. What

change can safely be tolerated is not

If the CO2 concentration becomes

yet known, From W. HaefeZe and W.

too high, then the resulting climate

Sassin , Energy strategies , Energy J 147

change could melt the polar ice caps,

(1976). Copyright 19 76, Pergmnon

increasing the ocean levels and floodin g press,

Ltd.

major coastal cities. Therefore, not all

of the available coal can be safely

burned.

limits of usable energy

Estimates of the limits of various energy sources are listed in Table 1Cl.

Compa ring these values with the estimated power dema nd of 50 TW in the year 2050 ,

we see that only solar, fission,

and fusion power can meet our long-term energy

needs.

Nuclear fission power appears to be the most economical power source in the

near .future. It has an excellent safety record.

Solution s to environme ntal pro-

blems, such as radwaste disposal, have been found, but politica l opposition is

hindering its development.

Som e estimates of solar power availab le in 2030 have been over 10 TW, but

the 3 TW limit reflects the time it takes to manufacture and move enormous quan-

tities of materia l and to "penetrate the market" econo mically (Haefele, 1979).

1D, Solar Energy

Solar heatin g and cooling of building s is already economically competitive in

some locations,

Solar electric power, however, may take longer to be economically

attractive.

Four schemes are receiving wide attention: photovoltaic, satellite

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lD, Solar

Enemy 7

Table lC1. Limits of various energy sources. Data from Rotty (1976),

Weingart (1979),

Hubbert (1975), HaefeZe (1979), and WaZton and Spooner (1976).

These are rough estimates,

but indicate the order of magnitude which coonbe

expected.

renewa ble energy sources

ingolar electric, heating & cool

biomass

wind power

wave power & t idal power

hydroelectric power

geothermal power

organic wastes

practically recoverable

fossi 1 fuels

coal E l ign i te

(2.35~1012

tons)

crude oi 1 (2.1~10~~ barrels)

natural gas (3.4~10~~ m3)

tar-sand oi 1 (3~10~~ barrels)

shale oil (1.9x1O11 barrels)

tota l

nuclear fission fuels

J-235

u-238,

Th-232

nuclear fusion fuels

I ithiu m for DT reactors

on land

POWER

LIMITS, TW

by

2030

ult imately

$3

~1001

3

10

1

3

.

1 1

1.5 2.9

0.2

0.4

0.1 0.1

ENERGY L IMITS

Joules TW-yea rs

53.2~10~~

1690

12.4~10~~ 390

13.1x1021 415

1 .8x1021 57

1.1x1021

35

i1

.6x1021 2590

Joules

1 022

1o25

. TW-years

300

3x105

Joules

2xlOTf

TW-years

6x1 o4

in oceans, conta in ing 0.17 ppm Li 2x107-8 6x108

deuter ium in oceans

8x10~~ 2x101

power stations , solar thermal, and ocean thermal power.

The simplest is photovoltaic panels (solar cells), which can be located on

individ ual building s. They cost about 10 $/peak Watt in 1980. Mass production

may reduce the price by an order of magn itude or more, as it did for the manu-

facture of transistors. However, a storage system will more than doub le the

initi al cost, and the average power is about l/4 the peak power, so the effective

cost per average Watt is an order of magn itude higher than the peak-Watt cost.

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8 lE, Fusion Reactions

Solar satellite power stations (SSPS ) would collect power with photovoltaic

panels on a satellite station in geosynchronous orbit (stationary over one point

on earth) and transmit the power to earth via 2.45 GHz microwaves. While they

appear to be technologically feasible, the SSPS can be economical only if major

reductions in the cost of orbiting heavy payloads are achieved.

The most popular solar thermal electric conversion (STEC) schemes involve a

central boiler heated by sunlight from an array of heliostats (reflectors). For

example, a 10 MWe demonstration plant at Barstow, Californ ia, uses a central

tower boiler surrounded by about 1800 heliostats, each with 40 m2 area, a nd

incorporates 3-4 hours of thermal energy storage in rock and heat-transfer oil

(Caloria). Assuming that a 50% load factor were achieved with on-site thermal

storage, commercial STEC plants of similar design operating under idea l solar

conditions might cost 2000-300 0 $/kWe, if collector costs could be held to 100

$/m2 or less.

Ocean thermal electric conversion (OTEC) systems use a fluid with a low boilin g

temperature , such as amm onia, to run a Rankine cycle heat engin e from ocean tem-

perature gradients. For example, warm surface water at 300 K could evaporate

amm onia in a boiler and drive a vapor turbine. Cool subsurface sea water at

278 K could cool the amm onia condenser to complete the cycle. Because the

AT

is

so small (around 20 K), the cycle efficiency will be very low, necessitating high

water flow rates and large, expensive heat exchangers. Other domin ant cost items

are the floating ocean platform, the cold water pipe, and the cable to carry the

electricity to shore. Alternatively, the electricity could be used to produce

hydrogen by electrolysis of water, and liquif ied hydrogen could be shipped as a

fuel.

Excluding the cable cost, a 250-400 MWe plant is expected to cost about

2000 $/kWe (19 78 $).

It appears that various forms of solar power could produce electricity at

costs of 70-100 mills/kWh, compared with about 20-40 mills/kWh for other sources

(1 mil l = .OOl $). Rapid deploymen t of solar electric power stations is limite d

by the huge surface areas which must be covered with collectors. The 24-hour

average solar power flux in the Southern United States is on the order of 200-

300 W/m2. The flux is somewhat higher near the equator, and lower in northern

latitudes. Abou t 100 TW thermal energy might ultimate ly be collected by covering

10% of the earth's desert areas with collectors. This is the basis for the

speculative figure of Table lC1.

In spite of the advantages of solar power, it is still desirable to develop

cheaper power stations which do not require a sunny climate, large collector

areas, and large energy storage systems.

lE, Fusion Reactions

energy release

Nuclei with interme diate masses have the lightest average masses per nucleon,

as shown in Fig. 1El.

When light elements are fused to gether or heavy elements

are split apart, the resulting interme diate elements

have less mass per nucleon.

The excess mass

AM

s converted into kinetic energy :

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lE, Fusion Reactions

9

W = 4Mc2 =

(total inita l mass - total final mass)c2

where c is the speed of light.

.

EXAMPLE ROBLEMEl

1 OOlO -

(1El)

CaZcuZate the

energy reZeased

by the

reaction D + T+ 4He + n.

Using nuclear masses from App. B, we

c

have

AM = 2.013553 + 3.015501 - 4.001503

- 1.008665 = 0.018887 u

= 3.13631x1O-2g kg,

so W = AMc2 = 2.8188x10-l2 J

= 17.593 MeV.

79990 -

0

Fig. lE1.

m

Average mass per

melleon vs.

atomic mass nwnber. From R. D. Evans,

F.9985 -

The Atomic IVzuZeus, p. 295, copyright

9

1955, McGraw-Hill, Neu York. Used by ?9980-

I I I I

pemrission of McGraw-Hi22 Book Company.

0

50 100 150 200

Atomic Mass Number A

fusion fuels

Possible fusion reactor fuels include H, D, T, 3He, 6Li, and llB. Som e

nuclear reactions of interest are shown in Table 1El. If the initia l particles

have energies ~0.1 MeV , then the kinetic energy of the reaction products is

divided up approximately in inverse proportion to their masses (to conserve mom-

entum). For the DT reaction, the neutron gets 4/5 and the alpha particle (4He)

gets l/5 of the kinetic energy.

The DT reaction is the most probable reaction at temperatures attaina ble in

fusion reactors. (Reaction rates and probab ilities will be discussed in Chapter

2.) Since deuterium constitutes 0.0153% of natural hydrogen, it is very abunda nt.

The amoun t of tritium in nature is negl igible , so it must be produced artificially.

It can be produced by neutron absorption in lithium , as indicated in Table 1El.

(Seawater contains 0.17 ppm of Li and 0.003 ppm of U.)

The DT reaction has the follow ing disadvantages:

* It is necessary to breed tritium from lithiu m (Chapter 27).

* The 14.1 MeV neutrons cause radiat ion dama ge and make walls radioactive

(Chapter 24).

* Precautions are neede d to minim ize release of radioactive tritium

(Chapter 28).

* Only l/5 of the reaction energy is carried by charged particles and can be

directly converted into electricity (Chapter 26).

The two branches of the DD reaction (DDn, DDp) have roughly equa l probabil-

ities. If the T and 3He produced by these reactions react with more deuterium ,

then the net reaction is

6D + 2H + 2n + 24He + 43.2 MeV (1E2)

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10 lF, Fusion Reactors

Table lE1.

NucZear React ions

of Interest.

Numbers in parentheses are approx-

imate energies of reaction products, MeV.

The exact energies vary with angle

q $n$derf partitle energies.

l he symboh p, d, t , n, and a represent

1 '1 '1 ' 0

n, and ,He.

energy yield

name fusion reactions

abbreviated form MeV

Joule

DT: D + T + 2He (3.s) + in (14.05)

T(d,n)4He 17.59 2.818xlo-'2

DDn :

zHe(.82) + in(2.45) D(d,n) 3He 3.27 5.24~10-~~

D+D+

DDp : T(l.01) + ~(3.02)

D(d,p)T

4.03 6.46x10-3

TT: T + T + in + ln + ZHe

T(t,2n)4He 11.3 1.81~10~ ~

D-3He: D + ZHe + ;Hei3.66)

+ ~(14.6)

3He (d , p) 4H e

18.3

2.93x10-12

p-6Li : p + :Li + ZHe + ZHe 6Li (p,a) 3He 4.02 6.44x10-13

p-llB: p +ltB + 3(zHe)

11B(p,2a)4He 8.68 1.39x1012

reactions for breeding tritium (Natural lithiu m is 7.5% 6Li, 92.5% 7Li.)

n-6Li : Li + in(therma1) -t

7*-

IzT2.5~

;He(2.05) + T(2.73)

6Li (n,a)T 4.78 7.66x10=

n-7Li : ZLi + in (fast) + T + ZHe + in

7Li (n,n ,a)T -2.47

-3.g6x10-13

(endothermic)

which is called the "catalyzed DD reaction",

since the high-prob ability DT

reaction has the effect of a catalyst.

The average yield per deuteron is 7.2 MeV,

which is an energy yield of 3.44~10'~

J/kg.

The "catalyzed DD" fue l cycle

eliminat es the need to breed tritium from lithium , but it requires higher temper-

atures and has lower power densities than the DT reaction.

Because of the more

advanced technology required for the DD and D-3He reactors, these are called

"advanced fuel" reactors.

The 3He produced in a DD reactor could either be burned in the same reactor or

burned in a "satellite reactor" using primarily the D-3He reaction. The advantage

of D-sHe satellite reactors is that the neutron emission rate could be greatly

reduced, resulting in much less wall activation and radiation damag e.

The p-6Li and p-

llB reactions are practically free of neutron emission, and all

the reaction products are charged particles, amen able to direct conversion. How-

ever, these "exotic fuels" also have low power densities and require even higher

temperature operation than the "advanced fuels", so it will be difficult to make

an economical reactor using the exotic fuels.

IF, Fusion Reactors

The two main requirements for build ing a fusion reactor are to

heat

the fuel

to ignition temperature and to

confine

it while it "burns".

Why is heating necessary before fusion reactions occur ? The positively

charged nuclei repel each other, and cannot approach close eno ugh for a nuclear

reaction to occur unless they have high relative velocities.

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1F. Fusion Reactors

11

Imagine trying to break an egg inside a foam rubber sphere by throwing other

eggs in foam rubber spheres at it.

They will merely bounce off unharmed unless

you throw them at high veloci ty. In this analogy the egg is l ike the nucleus of

deuterium or trit ium, and the foam rubber represe nts the coulomb potential field

surrounding the nucleus.

Only when the ions have large relative velocities can

they push through the coulomb barrier to produce a nuclear reaction.

In order to overcom e the barrier, the ion's kinetic energy mu st almo st equal

the potential energy of repulsion of the two point charges, For exam ple, the

required ener y

(about 5x10-l

3

for a deuteron

and

a triton to approach within a nuclear diameter

m) is found from E q. (lA4) to be about 290 keV. Because of the

quantum-mechanical

"tunneling" effec t and because some particles have muc h higher

velocities than the average, the actual fuel temperature s required for the DT

reactions are

T z 10 keV -.lOs K. (lF1)

The

ion"

required confineme nt time T is given approximately by the "Lawson

criter-

where n is the plasma ion density (ions/m3).

required confinem ent time is about 1 s.

I f n = 102* mm 3, then the

The temperature s required to burn various fuels will becom e apparent from a

study of nuclear reaction rates in Chapter 2. Following a discussion of radia-

tion losse s in Chapter 3, the confineme nt times required for various conditions

will be derived in Chapter 4.

research progress

Fusion research expe riments fall into two general catego ries: magn etic

confinem ent and inertial confinem ent. Magnetic conf inement employs strong

magn etic fields to provide thermal insulation between the plasma and the chamb er

walls. Inertial confineme nt allows free plasma expansion and cooling, but relies

on an extrem ely high density n to attain the Lawson criterion in the short

expansion time (typically a few ns). The high density is attained by comp ressing

a solid fuel pellet to over 1000 times its initial density, using laser beam s

or ion beams.

Fusion research experime nts began in the 1950's, with hopes of rapid s ucc ess ,

but plasma instabil it ies spoiled confinem ent. W ays to prevent various

instabil it ies were found in the 1960's, as plasma theory ma de great progress.

Man y nations shifted experimental emph asis to tokam aks in the 1970's, following

Soviet experimental suc ces s. Major experimental programs in inertial confineme nt

fusion (ICF ) were initiated in the 1970's, following optimis tic predictions of

attainable energy yields, In the late 1970's several other plasma confinem ent

sche me s have shown promise , including tandem mirrors, the field reversed pinch,

ohmically-heated toroidal experime nt, s tellarators, Elmo bum py torus, and

compact toroids.

The magnetic conf inement and ICF programs wi ll both demonstrate break-even

conditions (fusion power exceeding input power) in the mid-1980 's, but man y

engineering problems remain.

A Fusion Engineering Device will be constru cted to

demo nstrate small-scale power production, to test reactor materials, and to

develop various aspe cts of fusion technology.

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12

lF, Fusion Reactors

Fig. 3Fl. Schematic diagram of a magnetic confinement fusion power pkwzt. From

H. J. WiZZenbeq, T. J. Kabele, R. P. May, axd C. E. WiZZingham, "MateriaZs flow,

recycle, and disposal for deuterium-tritium fusion", PA?&2830 (1978), Fig. 1, p.3.

power plants

Some eleme nts of a fusion power plant are il lustrated in Fig. 1 Fl. The plasma

heating syste m is not shown. An ICF power plant wi l l have simi lar compone nts,

but no magn et coils (unless the blast chamb er walls are mag netically protected).

Potential applications of fusion power are show n in Fig. lF2. Fusion reactor

design studies est imate electrical power costs of about 35-40 mil ls/kWh (1980

constant $),which are comparable to costs of power from f ission and fossi l fuel

plants.

Est imated costs of solar electrical power are 70-100 mil ls/kWh

(Weinga rt, 1979). Fusion power will be especially valuable if

* fuel imports are limited

* coal use cannot rapidly increase (due to mining, transportation, or

environmental l imitations)

* the LMF BR is not rapidly cotmnercialized

* solar electr ic power costs do not become competi t ive

* discoun t (interest) rates are not too high

* fusion can be developed rapidly.

The developm ent of fusion power will probably cos t about30 bil lion dollars.

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FORMS OF

FUS I ON ENERGY

OUTPUT

lF, Fusion Reactors

13

PROCESSES

POTENT I AL

APPLICATIONS

I

METHANOL

HYDROGEN & COAL

I I I I L I

OF FISSION WAST ES

I

) NEUTRON ACTIVATION

ANALY S I S

NEUTRON RAD I OGRAPHY

I

ELECTRICITY

I

/

--) IRON E ALUM INUM

FUSION TORCH WITH

+ PLASM A CENTRIFUGE

ORE REDUCTION

WASTE MATERIAL

RECYCLE

I

HYDROGEN BY

PHOTOLYS IS OR

L RAD * - -

FERTILIZER

HYDROGEN &

NITROGEN

IULY>IS 1

METHANE GAS

HYDROGEN &

I

X-RAYS, GAMMA-RAYS,

ULTRAV I OLET

RADIATION

1 tlYlJKULY 3lS J

.

FISH & SHRIMP

PRODUCTION

I

t STERILIZATION 1

)

& SEWAGE

TREATMENT

I

INDUSTRIAL ) DISTRICT HEATING &+

GREEN HOUSE

AIR CONDITIONING

AGRICULTURE &

HYDROPONICS

4

Fig. lF2. Potential applications of fusion power. ("Magnetic Fusion Program

Swnrnq Docwnent",

Report HCP/T3168-01, prepared by TR W, Inc. for the U. S.

Depa rtment of Energy, 1979.)

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14

lG, Sumnary

lG, Summwy

The world power demand wi l l r ise to tens of TeraW atts in the 21st century.

Mo st of the rise will be in developing nations, so efforts by industrialized

countries to conserve energy will not prevent the power demand increase.

Fossi l

fuels w ill be nearly exhauste d by 2030, exce pt for coal. E nvironmental problem s,

such as CO2 accumulat ion in the atmosphere, may l imit the al lowable coal

consumption.

Tidal, wave, wind, hydroelectric, geothermal, biomass, and organic

;;+,Q;E power together will be inadequate to mee t-the earth's long-term energy

.

Only fission, solar, and fusion power will be adequate.

Fission breeder reactors are already succ ess ful. The huge collector areas

and energy storage sys tem s required by solar electric power plants mak e it

di f f icul t to br ing costs down. Fusion power plants offer the prospects of

continuous operation and cheap , abundant fuel. How ever, there are sti l l ma ny

problems to solve, and i t wi l l be many more years before the development of

fusion power is complete.

Problems

If a person's body burns 2000 kcal/da y of food energy, wha t is his average

Altabolism (Watts) ? How many TW food energy would be needed to feed eight

bil lion people a t this rate ? If each Joule of food energy required 8 J input

to agriculture, how man y TW would be required for agriculture ?

2. Calculate the energy yields of the DDn and DDp react ions.

3. Est imate the energy costs of the fol lowing forms of energy ($/MJ) :

a. 1 l iter of gasoline at $ 0.50 (heat of com bustion 47 MJ /kg , and density

705 kg/m3 ).

b. 1 slice of apple pie (300 kcal) at $ 0.90 .

c. electr ic ity at 50 mi l ls/kWh.

d. energy storage in a lead-acid battery storing 80 Amp-hr at 12 V and

cost ing $ 50 .

e. work by a draft horse laboring 8 hours/day at a power of 1 kW , and

cost ing $ 15/day for care.

4. A 3 GW th (Gigaw atts thermal power) fusion reactor operates at full power

70 % of the time for a year, burning catalyzed DD fuel. How many kg of

deuter ium wi l l be consumed ? How many cubic metres of water are needed to

extract this much deuter ium ?

5. Ho w ma ny litres of gasoline are required to produce the sam e energy as the

energy o f deuterium from 1 liter of water burned in a catalyze d DD reactor ?

(Data on gasoline is given in Problem 3a.)

6. A fusion reactor has a cylindrical coil with 8 = 5 T inside and 8 =

0

outside.

The coil current is 10 kA, and the internal volume is 500 ma . Estim ate the

(

approxima te stored energy o f the mag netic field (Table JAJ) and the coil

inductance.

7. Assuming that the world power consumption grows at 6 %/year from PO= 8 TW in

1980, and that 80 % of the power come s from fossi l fuels, in what year

would the fossi l fuels be exhausted ? [ W = / dt P(t) 1.

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1, Bib1 owaphy

15

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energy

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