English Summary

Study on Construction of Electric Power System Aimed at Renewable
Energy Expansion
Because the power-supply equipments were terribly influenced by the Great East
Japan Earthquake on March 11 of 2011, almost all nuclear power plant operations havebeen suspended, which influences the reduction of greenhouse gas emission. Under
these circumstances, the promotion of renewable energy is getting very important as ameasure which can realize reduction of greenhouse gas emission and ensuring of energy
security simultaneously.
Among renewable energy souces, wind power is especially expected to be expanded
because of its abundant potential. On the other hand, wind energy is concentrated inareas far from demand centers such as Hokkaido and Tohoku where there are notenough power grids, and it’s difficult to transmit the electricity from wind power plants
in those areas. Therefore, construction of electric power system is indispensable for
expansion of wind power generation.
In order to deal with such situations, some projects have begun in part of the nation
lead by ministries, but country-wide and comprehensive arrangement has not
implemented yet. And so it is important for expansion of wind power generation to
figure out the areas where construction of electric power system is needed on anationwide scale and consider the method to construct transmission line.
In this project, in order to contribute to the expansion of wind power generation, themethod and plan to construct transmission line for wind energy and the estimatedconstruction cost of transmission line have been studied.
In particular, supposing the capacity of wind power generation in 2050, promisingareas for wind power generation were extracted and selected from all over the country,
and the areas requiring construction of electric power system were figured out.
Furthermore, for 3 areas of which introduction potential is large - Hokkaido (Northern
Area and Eastern Area) , Tohoku, and Kyushu , layout plans of transmission lines weresuggested based on the optimaization calculation and approximate costs forconstruction were estimated.

1

Project Overview

Basic policies of this study are as below;Supposing the capacity of wind power generation in 2050, method to construct- S-1 -

additional transmission lines for wind energy to meet the supposed capacity is
considered and approximate construction costs are estimated.
In order to reduce the influence of annual variation to the utmost extent, thewind conditions throughout the country is calculated based on the numerical
weather simulations over the past 20 years and applied newly in this project.



Access points with existing electric power system are existing substations towhich transmission lines of more than the second highest voltage in eachelectricity supply area, e.g. 275kV, are connected. The voltage of transmission
lines to be constructed onshore additionally is the third highest voltage in eachelectricity supply area, e.g. 154kV.

Both onshore and offshore (bottom-mounted / floating) wind power generations
are considerd in this project.
Figure 1 shows the flow diagram of this project.

(1) Preparation of data for
analysis 【nationwide】】(3) Extraction and selection ofpromising areas for wind power
generation 【nationwide】】① Preparation of windcondition data

① Extraction and selection ofpromising areas for onshore
wind power generation② Preparation of GIS Datasuch as Natural Conditions② Extraction of promising areas
for offshore wind power
generation(5) Study of power system construction method【onshore, selected areas】】① Setting of power system construction study
areas and supposed capacity for those areas② Study of basic transmission line layouts foreach power system construction study area
③ Evaluation of power flow and voltage
profiles(2) Setting of basic scenario andsupposed capacity【nationwide】】(4) Organization of transmission line
construction method【onshore】】① Setting of basic scenario① Organization of items forinvestigation and design required forconstruction of transmission line

② Calculation of introduction
potential for each scenario② Organization of construction
method by terrain condition andothers

④ Setting of power system construction available
area along with environmental investigation andoutline design
1. Setting of power system construction
available area

2. Environmental investigation
3. Outline design③ Setting of supposed capacity
for each electricity supply area

③ Working-out of construction
cost per unit

4. Comparison of environmental impact
and construction cost

Figure 1 Flow Diagram of Project
The items taken into consideration in this project are shown below;
1. Supposed capacity of wind power generation across the country in 2050 was set
by reference to existing target values set by other agencies or associations.
2. Supposed capacity of wind power generation across the country was allocatedto each electricity supply areas and each location types (onshore / offshore(bottom-mounted / floating)). In this regard, wind farms in each electricity- S-2 -

supply areas were basically connected to the power systems which blong tocorresponding power company. But, as for Fukushima prefecture, which islocated in Tohoku District, additional case such that wind farms in eastern
rigion (Hamadori region) were connected to the power system of Tokyo ElectricPower Company (TEPCO) which is extended to this region (“Shin-Fukushima
utilization case”) was also considered.
3. Data needed in this project were prepared based on latest and open
information. But, when the data or information is difficult to obtain, theassumed data was used.
4. Supposed capacity or introduction potential was set based on installed capacity[kW]. (not based on generated energy [kWh])
5. Extraction and selection of promising area and study of basic transmission line
layouts were implemented under certain conditions and judged artificially.

2

Content of Implementation

The contet of implementation in this project is as below;（１）

Preparations of data for analysis①

Preparation of wind condition data

In order to apply to calculation of introduction potential across the country andextraction and selection of promising area, and so on, the high-resolution wind condition(1 hour and 500m in time and spatial mesh respectively, 80m altitude) was calculated
besed on the numerica weather simulation over the 20years (1991 - 2010) targeted atelectricity supply areas of 6 power companies - Tokyo, Chubu, Hokuriku, Kansai,
Chugoku, and Shikoku. Then, the data was made into public database which isconsistent with the previously built Kyushu and Okinawa database in FY2013.
Furthermore, the public database was marged with the previous database into thecountrywide database.
Table 1 shows the specification summary of the high-resolution weather simulation
and Table 2 shows the specification summary of the wind condition database. Figure 2
shows the map of average annual wind speed over 20 years across the country. Standard
deviations of yearly annual wind speed include the simulation errors derived bycomparison with observation values at meteorological stations in the target area.
Occurrences of winds according to directions (16 directions) based on wind speed
classification were visualized as wind-rose diagrams so as to grasp the wind-direction
traits.

- S-3 -

Table 1 Specification summary of the high-resolution weather simulation
Caluculating area

Calculation
period6 electricity supply
areas: Tokyo, Chubu,
Hokuriku, Kansai,
Chugoku, and Shikoku

1991 - 2010
(20 years)

Simulation resolution
Horizontal
Vertical
500 m

10 m or more

Temporal
１ hourTable 2 Specification summary of the wind condition databasedatabase component
Average annual wind speed over
20 yearsStandard deviations of yearly
annual wind speed
Maximum annual wind speed inyearly annual wind speed
Minimum annual wind speed inyearly annual wind speed
Occurrences of winds according
to 16 directions

content
20-year average of annual wind speed [m/s]（simulation errors not considered）
Standard deviations of yearly annual wind speed over 20 years[%]（simulation errors considered）
Maximum annual wind speed in yearly annual wind speed [m/s]（simulation errors not considered）
Minimum annual wind speed in yearly annual wind speed [m/s]（simulation errors not considered）
Occurrences of winds according to 16 directions over 20 years- S-4 -

Figure 2 Map of average annual wind speed over 20 years across the country(80m above ground level or sea level, distance from coast line less than 50km)- S-5 -

②

Preparation of GIS data such as natural conditions

The GIS (geographic information system) data such as natural conditions, social
conditions, legal systems, and information about electrical equipment was prepared foruse in the lower process like extraction and selection of promising area for wind power
generationon the basis of published data. The GIS data of following information were

newly created in this project: Japan Self-Defence Forces bases, U.S. military base,existing transmission lines, existing power plants, existing substations and existing
switching stations. Figure 3 and Figure 4 show the maps of created GIS data.

Figure 3 Example of GIS data map (SDF base)- S-6 -

Figure 4 Example of GIS data map (electrical equipments)（２）①

Setting of basic scenario and supposed capacity
Setting of basic scenario

In order to figure out available wind resources in 2050, scenarios for the future social
situation relavant to environment, etc. were considered.
In regard to onshore wind energy, 2 scenarios were set depending on 2 environmental
items of unfeasible conditions for wind turbine installation; protection forest areas, and- S-7 -

habitats of golden eagle and mountain hawk-eagle. The basic scenario includes both
items in infeasible conditions, and the referential scenario excludes both. The reference
scenario was implemented only for Tohoku Electric Power Company supply area.
As for island areas, only the main island of Okinawa was taken into consideration.
Table 3 and Table 4 show the estimation conditions of introduction potential foronshore wind power generation and offshore wind power generation respectively.
Table 3 Estimation conditions of introduction potential for onshore wind power
generation (unfeasible conditions)Category

Naturalconditions

Legal systems

Item
Annual mean wind
speed
Altitude
Maximum tilt angle
Above-groundopening

Legal systemclassification

City planningclassification
Socialconditions,landuse, etc.

Land-useclassification
Distance fromresidential area
OthersConsideration
for rareraptoresgolden eagle,
mountainhawk-eagle

Basic scenario
Exclude protection forest,and habitat of golden eagle
and mountain hawk-eagle

Referencialscenario
Include protection forest,and habitat of golden eagle
and mountain hawk-eagle

Less than 6.0m/s

Less than 6.0m/s

1,200m or more
20 degrees or more

1,200m or more
20 degrees or more

Less than 75 degrees

Less than 75 degrees

1)Special protection zones
and Class 1 special zones
within national andquasi-national parks2)Class 1 special zones
withinprefectural
natural parks
3)Wilderness areas4)Nature
conservationareas5)State-designated andprefecture-designatedspecial protection zones
within wildlife protection
areas6)World natural heritage
sites7)Protection forest areas
Urbanization promotion
areas
Fields, building lots, lots
used as trunk
transportation lines, rivers
and wetlands, golf courses1)Special protection zones
and Class 1 special zones
within national andquasi-national parks2)Class 1 special zones
within prefectural natural
parks3)Wilderness areas

Urbanization
promotion
areas
Fields, building lots, lots
used
as
trunk
transportation lines, rivers
and wetlands, golf courses

Less than 500m

Less than 500m

Areas restricted by the Civil
Aeronautics Act
Meshs surrounded byhabitat meshs in all
directions

Areas restricted by the Civil
Aeronautics Act- S-8 -

4)Nature conservation areas
5)State-designatedandprefecture-designatedspecial protection zones
within wildlife protection
areas6)World natural heritagesites

Table 4 Estimation conditions of introduction potential for offshore wind power
generation (unfeasible conditions)Category

Item

Natural conditions

Legal systems②

Basic scenario
Bottom-mounted: less than 7.0m/s
Annual mean wind speed
Floating: less than 7.5m/s
Distance from coast line 30km or more
Water depth
200m or more
Legal system
1)Marine park zones within nationalclassificationand quasi-national parks

Calculation of introduction potential for each scenario

The introduction potential for wind power generation in each electricity supply area
was calculated for each scenario on the basis of the data (wind condition data and GISdata) prepared in the upper process. The outcome of this calculation is to be used forsetting of supposed capacity for each electricity supply area in the lower process.
Table 5 shows the calculated introduction potential in each electricity supply area.
Table 5 Calculated introduction potential in each electricity supply area
Unit: GWElectricity
supplyarea
Hokkaido
TohokuTokyo
Hokuriku
Chubu
Kansai
Chugoku
Shikoku
KyushuOkinawa
Sum
Hamadori③

OnshoreBasic
Referencescenario
scenario
118.23181.78
38.03
88.78
2.84
6.18
2.46
5.18
5.86
11.29
6.56
16.12
6.57
18.89
2.71
6.10
6.58
14.19
1.74
1.84
191.57350.35
3.69
4.64

Total
248.45
79.01
47.85
0
26.21
1.14
0
4.81
5.69
3.48
416.62
3.07

Offshore
Bottommounted
92.21
21.62
21.48
0
11.00
0.13
0
1.57
1.07
3.47
152.56
3.07

Floating
156.24
57.39
26.37
0
15.20
1.01
0
3.24
4.62
0
264.070

Setting of supposed capacity for each electricity supply area

Supposed capacity of wind power generation in 2050 for each electricity supply areaand each location types (onshore / offshore (bottom-mounted / floating)) was set on thebasis of introduction potential by reference to existing target values. The allocation
method to each electricity supply areas and each location types was decided according to
the method published by Japan Wind Power Association in June 2012.
Table 6 shows the supposed capacity for each electricity supply area. As for
Shin-Fukushima utilization case, the supposed capacity for Tohoku area except
Hamadori region in basic scenario was set to 22.2 GW (11.1 GW for onshore, 11.1 GW
for offshore respectively), and the capacity of Hamadori region (included in the value of- S-9 -

Tokyo area) was set to 2.1 GW. Also, the supposed capacity for Tohoku area except
Hamadori region in reference scenario was set to 8.1 GW (4.0 GW for onshore, 4.1 GW
for offshore respectively).
Table 6 Supposed capacity for each electricity supply area
Electricity
supplyarea
Hokkaido
TohokuTokyo
Hokuriku
Chubu
Kansai
Chugoku
Shikoku
KyushuOkinawa
Sum

（３）
①

Total
4.50
25.00
15.00
1.20
10.30
3.50
3.20
2.20
4.50
0.60
70.00

Basic scenario
Offshore
Onsho
Botto
Floati
re
Total
m-mo
ng
unted
4.00
0.50
0.50
0
12.50
12.50
7.00
5.50
1.40
13.60
7.10
6.50
1.20
0
0
0
2.90
7.40
3.60
3.80
3.20
0.30
0
0.30
3.20
0
0
0
1.30
0.90
0.30
0.60
3.20
1.30
0.40
0.90
0.60
0
0
0
33.50
36.50
18.90
17.60

Total
Total
3.70
11.50
16.60
2.50
13.00
8.30
7.10
3.40
8.30
0.60
75.00

Unit: GW
Reference Scenario
Offshore
Onsho
Botto
Floati
re
m-mo
Total
ng
unted
3.30
0.40
0.40
0
5.70
5.80
3.80
2.00
3.00
13.60
7.10
6.50
2.50
0
0
0
5.60
7.40
3.60
3.80
8.00
0.30
0
0.30
7.10
0
0
0
2.60
0.80
0.30
0.50
7.00
1.30
0.40
0.90
0.60
0
0
0
45.40
29.60
15.60
14.00

Extraction and selection of promising areas for wind power generation
Extraction and selection of promising areas for onshore wind power generation

Firstly, the promising areas were extracted on the basis of introduction potential areas
derived in th previous process. As for the electricity supply area of which introduction
potential is much larger than supposed capacity, the stricter condition was applied.
Secondly, based on the firstly extracted promising areas, aggregated meshes feasible forwind farm were selected manually based on terrain information and so on. The secondly
selected promising areas are to be used as objects of the study of power systemconstruction method in the lower process.
Table 7 shows the extracted and selsected promising areas for onshore wind power
generation.

- S-10 -Table 7 Extracted and selsected promising areas for each electricity supply area
(onshore wind power generation)
Electricity
supply area

Promising area

SupposedcapacityFirstly
extracted
(GW)

(GW)

(GW)

(ratio)Hokkaido

400

1,051

969

2.42

Tohoku

1,250

871

1,987

1.59

Tokyo

140

284

203

1.45

Hokuriku

120

246

192

1.60

Chubu

290

586

340

1.17

Kansai

320

656

327

1.02

Chugoku

320

657

407

1.27

Shikoku

130

271

149

1.15

Kyushu

320

658

348

1.09

OkinawaSum②

Secondly selected

60

174

166

2.77

3,350

5,454

5,088

1.52

Extraction of promising areas for offshore wind power generation

Promising areas were extracted within the calculation condition of supposed capacity
preferentially from the nearest area to each access point.
Table 8 shows the extracted and selsected promising areas for offshore wind power
generation.
Table 8 Extracted and selsected promising areas for each electricity supply area
(offshore wind power generation)
Electricity
SupplyArea

Supposed Capacity(GW)

Promising area

Hokkaido

bottommounted
0.50

0.00

Firstly extracted (GW)
bottomfloating
mounted0.68 (10 km)
0.00

Tohoku

7.00

5.50

9.91
7.52

floating

Tokyo

7.10

6.50

Hokuriku

0.00

0.00

(30 km)9.02(30 km)

15.26

-

-

Secondly selected (GW)
bottomfloating
mounted0.60 (10 km)
0.00(40 km)7.47(50 km)7.60-(30 km)8.96(40 km)

7.83

-

-

(80 km)(70 km)
-

Chubu

3.60

3.80

5.88

(20 km)5.58(20 km)4.37(20 km)4.75

Kansai

0.00

0.30

0.00

-

1.01

(30 km)

0.00

-

1.01

Chugoku

0.00

0.00

Shikoku

3.00

0.60

0.48

(30 km)3.04(60 km)0.48(30 km)2.69(60 km)Kyushu

4.00

0.90

0.44

(30 km)1.68(60 km)0.44(30 km)1.68(60 km)

-

35.59

-

20.96

-

26.92

Okinawa

0.00

0.00

Sum

18.90

17.60

-

-

24.91

-

-

(40 km)(30 km)---* Distance in parentheses means the largest distance from acsess point.

- S-11 -（４）①Organization of transmission line construction method
Organization of items for investigation and design required for construction oftransmission line

General work process for transmission line route setting was organized from the pointof investigation, surveying, design, and cost estimation. In addtion, scope of this project
was defined.
②

Organization of construction method by terrain condition and others

The latest information about application of surveying technology to setting oftransmission line route was organized. Furthermore, general construction method andspecification for transmission line was organized in accordance with terrain conditions.
③

Working-out of construction cost per unit

Transmission line construction cost per unit length (1 km) was worked out for eachvoltage class, each terrain class and each line type so as to be referenced in study ofbasic transmission line layouts in the lower process.
Average cost of 154 kV class and 110 kV class was estimated at 350 million yen per km
and 330 million yen per km respectively.
（５）①

Study of power system construction method
Setting of power system construction study areas and supposed capacity for thoseareas

In regard to each electricity supply areas, positional relashionships of secondly
selected promising areas to transmission lines were organised by superimposing both
maps.
Besides, 3 areas of which introduction potential is large - Hokkaido (Northern Area
and Eastern Area) , Tohoku, and Kyushu - were set as power system construction study
areas in this project.
The supposed capacity of Northern Area and Eastern Area of Hokkaido was set to be
3.3 GW according to the introduction potential ratio and so on.
②

Study of basic transmission line layouts for each power system construction study
area

The basic transmission line layouts, which are constructed with the new transmission
lines dedicated to interconnection from the access points on the existing power system
to the spread (secondly selected) promising areas, were organized in three areas- S-12 -(Hokkaido, Tohoku, and Kyushu) set as the consideration areas in the previous process.
In order to study about the basic layouts of transmission line, “Net Optimizer with
EXPRIMG” based on the Genetic Algorithm (GA) and the Extended-Prim’s Algorithm(Kousaka et al., 2014) was applied to the following optimization problems. In the
Genetic Algorithm (GA), the index considering wind condition, which was defined as thevalue obtained by dividing the construction cost for the new transmission lines with thetotal wind power generation (kWh), was minimized by choosing the adequate
combination of the (secondly selected) promising areas with satisfying the supposed
installation capacity. The construction cost for the new transmission lines wascalculated with the Extended-Prim’s Algorithm for determining the index considering
wind condition. The Extended-Prim’s Algorithm performs the adequate transmission
network to minimize the cost by connecting the chosen combination of the promisingareas with the new transmission lines considering the transmission capacity.
Table 9 and Figure 5 shows the each value and the layout of the network with
Shin-Fukushima utilization case in basic scenario.
Table 9 Each value of network with Shin-Fukushima utilization case in basic scenario

Area

Voltage Connected
capacity
class
(kV)

(GW)

Electricalenergyper year
(TWh)

Total
Total
construction
lengthcost(km)Construction cost

(million (thousand
yen/km) yen/kW)
147.91365
42,069(billion yen)

(yen/kWh)

Hokkaido
Tohoku(exeptHamadori)
Hamadori

110

3.516

9.18

154

11.18534.50 1163.9

436.07375

38,986

1.1

154

2.115

6.85

138.8

54.03

389

25,546

0.7

Kyushu

110

3.204

7.45

651.8

229.93353

71,766

2.8-

20.02057.98 2360.2

867.94368

43,354-Sum / Ave.

405.7

Transmission
cost (3%interest)- S-13 -1.4

Figure 5 Layout of the network with Shin-Fukushima utilization case in basic
scenario③

Evaluation of power flow and voltage profiles

In order to evaluate the power flow and the voltage profiles in the new transmission
networks, AC power flow calculation was applied to the basic transmission line layouts
calculated in the previous process.
In the case of the operation of constant power factor to 1 for all wind farms, the valuesof voltage could be in the allowable ranges within 95 % - 105 % of basic voltage,
therefore it showed the proper construction in the new transmission networks.
As the evaluation of the required reactive power and the power losses in the networks,- S-14 -the summary of the results was showed in Table 10 for the comparison of the constantoperation for all wind farms and the adjusted operation in power factor for each windfarm.
When the power factor of the wind farms was adjusted to minimize the required
reactive power from the existing power system to the new transmission networks rather
than to minimize the power losses in the network, the values of power factor could be in
the allowable ranges (Power factor allowable range: 0.90 - 1.00, both lag and lead). And
also, the values of the required reactive power from the existing power system could benearly 0 and the values of the power factor through each new transmission networks
could be nearly 1.0. Therefore the additional facilities such as SVCs were not requiredas the countermeasures which compensated the reactive power.
Table 10 Reactive power compensation and transmission loss for each accesspoint(Ploss ([%]): ratio to total generating capacity)
Electricity
supply area

Access point

Iwate
East route842.8MW
ShinFukushima
South route600.6MW
Memanbetsu
569.5MWOsumi
518.8MW
Kumamoto
386.9MW

TohokuHokkaido

KyushuConstant operation for all wind farms

Adjusted operation in power factor foreach wind farmPower factor 1.00
Ploss
Qsys
[MW]
[MVar]([%])

Minimizing Qsys
Ploss
Qsys
[MW]
[MVar]([%])

Constant voltage
Ploss
Qsys
[MW]
[MVar]([%])

Minimizing Ploss
Ploss
Qsys
[MW]
[MVar]
([%])

291.4

56.5
(6.70)

171.8

56.6(6.72)

113.9

52.5(6.23)

121.6

52.4(6.22)

67.1

20.1(3.35)

134.6

22.7(3.78)

0.0

20.0(3.32)-02.1

19.8(3.29)

86.6
163.8
115.4

16.7
(2.93)
32.4(6.25)
24.2(6.25)

114.9
92.7
87.3

17.3
(3.14)
32.9(6.34)
25.5(6.59)

0.0
63.9
0.0

16.3
(2.86)
30.5(5.88)
23.6(6.10)

-20.4
69.8
32.1

16.2
(2.84)
30.4(5.86)
23.1(6.02)

Ploss : active power loss, Qsys :reqired reactive power compensation from power system.

④

Setting of power system construction available area along with environmental
investigation and outline design

For several areas of basic transmission line layouts with large connected capacity,
power system construction available areas were set in view of land usage situations,
legal systems and so on. “Power system construction available area” is corresponding tothe outline route in a general transmission line investigation and design. Depending on
the situation of each area, multiple plans were considered in case the places to be
bypassed largely or the places feasible for construction of wind turbines were includedin the area.
Also, as for these areas, consideration matters related to environment in transimission- S-15 -line construction were organaized on the basis of existing materials investigation, andfield investigations such as landscape survey were conducted when needed.
Furthermore, the outline designs were implemented assuming concrete construction
method, and the approximate costs by the construction method were estimated. As forthe area where multiple plans were considered, the environmental impacts and theapproximate costs were compared between each plan.
Table 11 shows the selected areas for the outline route, and Table 12 shows thesummary of results for the outline design in each area.
Table 11 Selected areas for outline route
Hokkaido (1 area)
Area

Tohoku (5 areas)
Aomori, Iwate, Akita, Miyagi,
Hamadori

Memanbetsu

Kyushu (2 areas)
Kumamoto, Osumi

Table 12 Summary of results for outline design in eash area
Result of outline design (Plan A)
Voltage
No.

Area

Class
(kV)

Total
length(km)

Total

Construction

construction

cost

cost

(million yen(billion yen)/km)

Result of outline design (Plan B)

Ratio of

Total

mountains length
(km)

(%)

Total

Construction

construction

cost

cost

(million yen(billion yen)/km)

Result of basic transmission line layouts

Ratio ofConnected

Total

mountainscapacitylength

(%)

(MW)

(km)

Total

Construction

construction

cost

cost (*)(million yen(billion yen)

/km)

1

Memanbetsu

110

32.4

11.05

341.0

58%

30.5

10.06

329.8

49%

570

34.1

11.38

333.7

2

Aomori

154

94.8

34.10

359.7

47%

92.6

33.47

361.4

46%

824

95.7

33.23

347.2

3

Akita

154

98.1

36.61

373.2

54%

94.2

34.90

370.5

51%

848

94.8

33.42

352.5

4

Iwate

154

100.5

40.07

398.7

85%

100.6

39.82

395.8

85%

843

99.6

35.08

352.2

5

Miyagi

154

107.5

41.43

385.4

85%

105.7

40.81

386.1

84%

822

109.1

37.51

343.8

6

Fukushima

154

50.2

19.27

383.9

91%

44.5

16.66

374.4

90%

601

51.5

17.65

342.7

7

Kumamoto

110

66.0

22.83

345.9

78%

-

582

69.4

22.63

326.1

8

Osumi

110

66.8

24.29

363.6

83%

65.6

519

72.8

23.94

328.8

-

23.86

363.7

83%

(*) Excluding cost for substations

3

Conclusion

3.1

Descussion for result

In this project, 3 areas of which introduction potential is large - Hokkaido (Northern
Area and Eastern Area) , Tohoku, and Kyushu - were set as power system construction
study areas. In total of these 3 areas, line length was estimated to 2,360 km andconstruction cost was estimated to 867.9 billion yen (Shin-Fukushima utilization case ofbasic scenario).
Because it requires about 850 billion yen to construct transmission lines for wind
power generation of 20 GW in these 3 areas, the cost to construct transimission lines forwind power generation of 33.5 GW in all onshore areas is estimated to be 1.5 trillion yen
by simple calculation (approximately 1.7 times as large as total of 3 areas). On the other
hand, cost to develop wind power generation facilities of 33.5 GW is estimated toapproximately 10 trillion yen assuming unit cost of 0.3 million yen per km. Therefore,- S-16 -cost to construct transmission lines is estimated to about 13 % of total cost to introduce
wind power generation (11.5 trillion yen). Furthermore, transmission costs were
calculated to be 1 to 2 yen per kWh. These are 10 to 20 % of wind power generation costof 10 yen per kWh that is estimated in committee of National Policy Unit.
Because the main consideration in this project was the construction of newtransmission lines, there are areas where new transmission line construction are notplanned depending on the situation of power system construction, the wind farm scales
and others. However, these areas include the places where the existing transmission
lines are available or the places where small-scale wind farms can be constructed.
So far, there had been no study of planning the transmission lines for wind power
generation on a nationwide scale. The result of this project is greatly hoped to be
utilized for future transmission line construction.

3.2

Future challenges

Future challenges of this project are as below:（１）

For the future study1) Installed capacities of power stations or substations were taken or estimated fromlatest published values. However, it is hoped that more realistic study will be donewith future planned values to be taken into consideration. However, the study will
become more realistic if future planned values are taken into consideration.
2) In this project, 3 areas with large introduction potential - Hokkaido (Northern Area
and Eastern Area), Tohoku, and Kyushu - were set as areas for power systemconstruction study. However, studies for other areas including optimization
calculation are desirable to be conducted as well.
3) Only the existing substations were applied as access points in this project. However,
because thermal power plants such as oil-fired and LNG-fired are possible for flexible
power control, they are desirable to be applied as access points as well.
4) In islands connected to power systems such as Shodoshima Island and Amakusa
Islands, there are promising areas for wind power generation. Therefore, theseislands are also desirable to be taken into consideration.
（２）

For the implementation of construction project1) Transmission line layout plans were studied base on the promising areas for onshore- S-17 -wind power generation, which were selected by confirming terrain condition using
1:40000 scale topographic map. However, when implementing projects for wind power
generation or transmission line construction, it is necessary to grasp workability,
landowner situations and others in the field enough.
2) When implementing projects for wind power generation, it is necessary to conduct
field investigations of rare raptors, etc. which could be bypassing conditions whennarrowing down the routes.
3) When planning construction of the concrete transmission lines, it is important toconsider the way to reduce transmission line construction cost more, by promoting
coordination between wind farm construction process and transmission line
construction process (e.g., sharing of haul roads, efficient use of construction
equipments, sharing of environmental information about rare raptors and others).
（３）

About the offshore wind power generation

1) The offshore wind power generation is the developing technology. Therefore, theconstruction method, the transmission method (AC or DC), the installation plan fortransmission lines including offshore substations and others are subjects of future
investigation.
2) Considering mainly onshore wind power generation, wind condition data wasprepared at 80 m above ground level or sea level in this project. However, as windturbines for offshore wind power generation are getting larger (e.g., 5 MW, 7 MW),wind condition data on the ocean is desirable to be prepared at about 100 m.

- S-18 -