Comparison of the Fusion
with Other Prospective Energy Sources
OKANO Kunihiko, ASAOKA Yoshiyuki,
HIWATARI Ryouji, YOSHIDA Tomoaki
and TOMABECHI Ken

Central Research Institute of Electric Power Industry

1. Introduction
Since any power plant should be economicallycompetitive to the other power sources, the plant
economics is an important issue, but is just one of therequirements. The followings may be the major
requirements to be posed for the future energy sources;
1. Abundant and widely available resources
2. Low emission of CO2 as well as other undesirable
substances and less waste to be disposed
3. Acceptable cost (cost of electricity and capital costper kW) and flexibility in plant size (minimumsize)
4. Stable power supply and less vulnerability tointernational affairs
5. Safety and security (bio-hazard potential andglobal security risks)

In the present study, we compare the following fivepossible energy options that may satisfy most of theserequirements;
1) Terrestrial solar and wind power plants
2) Solar Power Satellites (SPS) on
Geosynchronous Earth Orbit (GEO)
3) Advanced fission plants; fast breeder
reactor (FBR) or light water reactor with
Uranium from seawater (LWR-SW)
4) Fusion reactor
5) Advanced coal plant with CO2 control
Is the fusion superior? (---or not?)If the fusion is superior, how?

Method of assessment
Five main issues relevant to the five requirements are
divided into sub-issues in order to clarify the various
view points on each main issue.
A weight W of each sub-issue is assigned in order toassess the options.
The sum of W over each issue is 10.
Table 1 Issues and the weight
Main issues
Sub-issues
WeightResource
1) Restriction on resource82) Resource distribution
2Environmental 1) CO2 emission
5Issues2) Disposability of waste
5Cost1) Cost of Electricity (COE)42) Construction cost43) Flexibility in plant size
2Stability of1) Stability of plant
8Power Supply(restriction in principle)
2) Vulnerability of operation2(to international affairs)
Safety and1) Hazard potential during
7Security
operation2) Security against improper3
use or nuclear proliferation

Steps of assessment
1) Ranking each option on the main issue.
The best option is ranked as 1st, the next 2nd---If one is very inferior, it should be ranked 5theven when there is no option ranked as 4th.
2)The point p=5 for 1st rank, p=4 for 2nd---3)The total point for a single main issue : P =Σ p·W
P = Σ p ・W
R e s o u rc e

10203040

50

E n v i ro n m e n t

e xa m p le
C os tS t a b ilit y

S e c u rit y

NOTE!! The weight for each main issue is not determined
here, because the purpose of this study is to show thefeatures of each option for the requirements, e.g., meritand demerit.
Comparing the point of each option over a single main
issue is meaningful, but the sum of points over all the main
issues can not be a general yardstick, because the weight ofmain issues have not been defined here.

1. Resource
1) Restriction on resource [Zetta(1021) Jouls: ZJ]
PowerReserve
Available energy
RanPlant(tons)(ZJ)
kSolarinexhaustible
inexhaustible, but
1windlimited by ~0.8 ZJ/year
SPS
inexhaustible inexhaustible but limited 1by capacity on GEO(~0.006 ZJ/year)**Fusion D(seawater):
1136
2.2x105.1x10Li(seawater):
2.4x1011
fissionU (mine):280 (FBR)
65.8x102600 (LWR-SW one
1U(seawater):through)4.7x1092.3x105 (FBR)
Coal
9.8x1011
26
5** 180 satellites at intervals of 2 degree on GEO =180GWe.

1)Solar/wind and SPS are inexhaustible. 1st2)Since the reserves of resource and available energies
from Fusion and Advanced fission is practicallyunlimited. 1st3)Note that, if the Uranium from seawater is used, theavailable energy attains 2600 ZJ even withone-through fuel strategy.

2) Resource distribution
PowerResource availability
RankPlant
Fission:
U: from seawater1
Pu: self-breeding
Fusion
D & Li: from seawater1
T: self-breeding
Solardepend on country (See Fig 1)
2windSPS
restriction in siting due to the large
2
space for rectena (see Fig 2)
Coal
82% of world resource is in China,
3
USA and former USSR area
1) The fuels for fission and fusion are available fromseawater, or by self-breeding. 1st2) The available energy from solar power and the available
area for wind power depend on the country. The rectena(a power receiver) of SPS is huge and may become acritical constraint in siting. 2nd3) Since the resource distribution of coal is localized (82%of world resource is in China, USA and former USSRarea). 3rdFig. 1
Resource distribution of solar and wind power
Eastern Europe & USSR area
Asia (developping)
Asia (developped)
North Africa & Middle East
South Africa
OceaniaJapan
Western Europe
North America
0500

1000

1500

2000

2500

3000

kwh/m2/yeara)Average power density of sunshine

Asia
Eastern Europe
Western Europe
South America
North America
Oceania
Africa051015202530
Arvailable area (%)

354045b)Area available for wind power plantFig.2 Comparison of plant area on the earth.
SPS Rectena(1 GW)
60km 224.2km / 7 plants
Kashiwazaki
LWR plant area
8.2GW in total
0.5 km 2 /GW
20.52km / 2 plants
MihamaLWR plant area
1.7GW in total
0.3 km 2 /GW

Note that the safety zone is excluded for the SPS rectena
while the areas for LWR include it. Also note that the areaof ITER (not commercial plant and not shown here) is 0.4km2.gC/kwh

2. Environmental Issue1) CO2 emission

9080
7060
50
403020100

CO2 Emission
3rd rank

85(w/ concernfor disposal)

1st rankplant

5.5

SPS

5.7

6~1216~34

homeFission Fusion Solar

one throughCoal

w/ CO2 cont.

1) The low emission group (SPS, Fission, Fusion, andSolar/Wind) should be ranked as 1st.
2) The coal is ranked as 3rd, because the emission fromcoal plant is higher than the above low emission groupand besides, there is some concern for disposal ofsequestered CO2 .
The other undesirable substances will be minor, except
for the coal plant.2) Disposability of waste (except CO2)Power
Description
RankPlant
Solar easily disposable and recycled,
1windno radioactivity
SPS
2x104 tons on GEO* is difficult to2
dispose, possibly no radioactivity
Coalhuge (2x107 tons from 1 GW plant),
3very low radioactivity
Fusion large (2x104 tons) and radio- active
3
waste, but neither high level nor longlife
fission high level and long life radioactive
5waste is difficult to dispose
1) Concerning the disposability of waste, the Solar/Windpower plant is no doubt the best. 1st2) On SPS, there is a concern on how to dispose a satellite(20,000 tons) on GEO. 2nd3) The ash from coal is huge. The waste from fusion is
20,000 tons throughout the plant life and it isradioactive, but neither high level nor long life. 3rd.
4) Since high level and long life radioactive waste from thefission plant is difficult to dispose, the fission plant isranked as 5th.

3. Cost
It should be noted that any issue can be reflectedto the cost.
For example, disposal cost of radioactive waste
should be included in the cost of fission plant.
Therefore the costs considered here may include
all the costs to achieve the features assumed in theother main issues.

1) Cost of Electricity (COE)
COE(yen/kWh)160
140

89-152120
100
80

Advanced Fusion Coal w/SPS
FissionCO2 cont.

25

Solar
plant

Solar
home

WindW ind

4th(home)

3rd44r(plant)

2nd

1stFission

023

SPS

20

17.5

Coal40LWRsw=10-15
FBR=7-10
12-15

Fusion605th1) The ambiguity in the COE for LWR-SW depends on theUranium cost from seawater.
2) The cost of Fusion reactors has been widely discussed
and there is large ambiguity. We have adopted here thecost based on advanced tokamak reactors, such as
ASSTR-2 (by JAERI) and CREST (by CRIEPI).
3) The cost of SPS is based on the value given in a reportby NEDO*.
*:New Energy and Industrial Technology Development Organization

2)Unit Construction cost
Power Plant
Unit cost of construction
for 1GWe plant(104 Yen /kW)
Coal with28
CO2 control
Advanced32
fissiona value of 1GW LWR
is used hereFusion
40~50
Solar orwindSPS

Solar: 80~130, ~31
Wind: 50240

Rank123351)The order of ranking is;Coal 1st, Fission 2nd, Fusion and Solar/Wind 3rd2) The construction cost of SPS is very expensive.5th3) Flexibility in plant size
Minimum scale of plant to be achieved without
significant COE increment is shown in this table.
Power Plant

Minimum scale of plant

Rank

Solar orwind
Coal with
CO2 control
Advancedfission:
FBR,LWR-SW
Solar Power
SatelliteFusion

flexible(no scale merit)~200 MW(no inherent limit)~300 MW(no inherent limit)

1~500 MW(no inherent limit)~1000 MW23451) The Solar/Wind is the 5th in COE, but the 1st in
Flexibility in plant size. This means that the issues on
cost must be discussed from various view points.
2) Although there is no inherent limit for plant size for
SPS, a strong constraint exists, because the size ofrectena seems to be determined by the beam divergencerather than the transmission power. 2nd3) The minimum size of fusion reactor will be restricted by
the inherent feature of fusion reaction. 5th

4. Stability of Power Supply
This main issue includes two sub issues;
1) The inherent operational restriction,"stability of plant".
2) A new concept on the plant stability,"vulnerability" of operation to international affairs,
where we have noticed that the plant output can beinterrupted if supply of fuel or resource is disturbed.

Stability of Power Supply

1) Stability of plant (restriction in principle)
Power Plant
Operational characteristics
Coal with CO2
control
Fission:FusionSPS
Solar or windRankstable1stablestablestablebut short discontinuations due
to eclipse by the earth
unstable

11151) The coal, fission and fusion plants can be operatedcontinuously. There is no limit, at least, in principle. 1st2) The SPS is also ranked 1st here, but note that the output
is to be interrupted due to eclipse by the earth before
and after the autumnal equinox and the spring equinox(less than one hour per day). 1st3) The solar/wind power plant is inherently unstable. The
cost to overcome this unstable feature, which is excluded
in our cost assessment, will be very expensive. 5th

Stability of Power Supply2) Vulnerability of operation (to international affairs)
Vulnerability to human evil and malice (like terrorism)
toward the plant is out of present consideration.

PowerPlant
Solar orwindSPSFusionFissionCoalDescription

Rank

invulnerable

1

invulnerable
invulnerable
less vulnerable, but if internationaltransports are required for the fuelcycle, there is some vulnerability.
vulnerable to international affair, if
imported fuel is used11231) The solar/wind power plant and SPS is highly
invulnerable to international affairs. 1st2) The fusion is also ranked as the 1st, because fusion fuelcan be obtained from seawater and the fuel cycle can beclosed in a single plant. 1st3) The fission plant is less vulnerable too, but ifinternational transports are required for the fuel cycle,
there is some vulnerability. 2nd4) The fuel availability of coal plant is possibly more
vulnerable than the other options. 3rd

5. Safety and Security
Since operational safety must be guaranteed forany commercial plants, it is a compulsory
requirement.
Therefore only the issues related to security
should be compared here.
When we consider the security of plants, we
assume here also peaceful world situation. Any
plants can be dangerous under the human malicesuch as war or terrorism.

The first sub issue for security is a ranking by thehazard potential in the plant during operation.
1) Hazard potential during operation
Power Plant
Relative value ofhazard potential
Solar or wind
regarded as 0SPS
regarded as 0
unknown effect by electromagnetic wave is conceivable,
but was excluded here
Coal withregarded as a low value
CO2 control
similar to chemical plants
Fusion~1/1000 (radioactive)
Fission1 (radioactive)

Rank112341) The solar/wind and SPS has been regarded as having nohazard potential. 1stThere might be some unfavorable effect by electromagnetic wave near the SPS rectena. (23mW/cm2).
It was neglected from the present consideration.
2) The hazard potential of coal plant is regarded as a low
value, i.e., similar to those of many chemical plants. 2nd3) The fusion and fission plants have a high hazard
potential. But the bio-hazard potential of fusion is lower
by about 1/1000 than the fission plant.
Fusion: 3rd Fission: 4th2) Security against improper use
This is related to the security against improper use ofplant, where 'improper' may mean unauthorized orinternationally unaccepted, e.g., use by terrorists or use
for proliferation of nuclear explosive devices.
Power Plant

Description

Rank

Solar or wind
Coal withCO2 control
FusionSPS

no insecurity
no insecurity

11

no merit for military use
1GW beam emitter from space
might be difficult to be acceptedby neighbors
security problem due to Pu andU235 is essentially unavoidable

12Fission51) From this view point, no insecurity is found for thesolar/wind plant and coal plant. 1stNo noteworthy merit is found for using the 'commercial'fusion reactor for such purposes. 1st2) The SPS, which can be regarded as an 1 GW power
beam emitter from the space, might be difficult to be
accepted by neighboring countries. 2nd3) The fission plant is very inferior from a view point of
nuclear proliferation. 5thInferior
Resource

Environment

Cost

1020Superior
304050C oa l
W / CO2 c on t.

SPS
F u si on

StabilitySecurity

S o lar/W i nd

F i s si on

Fig.3
Summary of point distribution

This figure of P =Σ p·W clearly shows thefeatures of each option. Each option hasdrawback(s).
1) The major drawback of coal is in Resource.
2) The serious drawback of SPS is Cost.
3) It is Stability for solar/wind.
4) The points of advanced fission plants are high enoughexcept for Security, and they appear to be a reliableenergy source for a long time. But difficulties associatedwith security may be unavoidable.

InferiorResource

Environment

Cost

1020

Superior
304050C oa l
W / CO2 c on t.

SPS
F u si on

StabilitySecurity

S o lar/W i ndF i s si on5) The points of fusion are also high enough.
The drawback of fusion is Cost, but it is still ranked as
3rd for Cost. This means that the fusion plant has noserious drawback.
The fusion gets the 1st for Resource and Stability,
but it is not a sole winner. This fact tends to make themerit of fusion somewhat ambiguous.
The superiority of fusion is due to the fact that
there is no serious drawback (i.e. no 5th rank).
When we discuss the future energy options, we should
consider what is the serious drawback as well as what is themerit.

Conclusion1) Rank and point for the requirements as futureenergy sources are assessed for the five options
selected.
2) Every option has drawback(s) as well as merits.
When we discuss the future energy options, weshould consider what is the serious drawback as
well as what is the merit.
3) The results of the study show that fusion reactor
does not mark a higher average point than otheroptions, but looks superior as a whole, meeting
every requirement reasonably well without
serious drawbacks for any of them.
4) Since a drawback of fusion is the issues relevant
to cost, a quest for a smaller plant size with lower
cost may be the most important issue tomaximize the attractiveness of fusion power
plants.
5) It is noteworthy that the issue for fusion is largely
scientific and technical, i.e., it might be overcome
by further efforts.