227

A Study on Sustainable Energy Systems
for Small Villages in Fukushima
Takuya TOGAWA1*, Yi DOU 2, Shogo NAKAMURA1 and Makoto OOBA1Fukushima Branch, National Institute for Environmental Studies
10-2 Fukasaku, Miharu Town, Tamura-gun, Fukushima, 963-7700, Japan
2
The University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan*E-mail: togawa.takuya@nies.go.jp*1

Abstract
We investigated the design and operation of distributed energy systems for the central area of Mishima
Town in the Oku-Aizu area of Fukushima Prefecture. These systems were tailored to the characteristics of theregion. Although we found that the deployment of an energy system utilizing forest biomass resources wasdesirable from the perspectives of CO2 emissions and economic circulation based on local natural resources,
the cost of energy was relatively high. Based on these results and related information, we considered theprocesses required for implementing energy systems utilizing forest biomass resources. Our results show thatto create sustainable communities based on renewable energy in rural areas with low population density, it isimportant to integrate energy system development with community development from a medium- to longterm perspective.
Key words :	autonomous distributed system, mathematical optimization, mixed integer linear programming,
regional revitalization, renewable energy

1. Introduction
Interest in renewable energies has grown against the
backdrop of global environmental issues, with the Great
East Japan Earthquake revealing the vulnerabilities oflarge-scale centralized electric power supply systems.
These two considerations have led to increased
nationwide momentum to promote the introduction of
distributed energy systems utilizing renewable energies(Nakata, 2015). In addition, frequent abnormal weather
events such as heavy rains and snowfalls in recent years
further have spurred this trend. This is particularly ofgreat concern in Fukushima Prefecture, Japan, which is
now suffering from all of these problems, necessitating acomprehensive solution for revitalization.
Up to now, however, technology and policies related
to resources and energy have been regarded as nationaland global issues and, therefore, “given conditions” that
could not be altered at the level of local living andeconomies. Adverse impacts have arisen due to the large
gap between the given conditions and local situations.
For example, in mountainous and other remote areas,
energy supply infrastructure such as gas pipelines has notbeen sufficiently developed. Thus energy prices havetended to be higher there than in urban areas. Rural
Global Environmental Research
24/2020: 227-236
printed in Japan

communities have been unable to implement effective
measures to address such situations. Especially in cold
regions where there is great demand for space heatingand hot water supply, utility costs are a burden forhouseholds. Furthermore, inadequate space heating andhot water supply systems along with poor building
insulation lower residents’ quality of life.
Meanwhile, Japan’s 5th Basic Environmental Plan
has advocated maximizing the vitality of regions by using
regional resources to build self-reliant, decentralizedsocieties based on the characteristics of regions and, tothis end, proposes the concept of regional circular andecological spheres that complement and support regional
resources. The introduction of renewable energy isregarded as a substantive measure that will contribute to
the creation of such regional circular and ecologicalspheres (Shirai, 2018a; Shigeto et al., 2018). Effective
use of forest resources has been recognized as a key issue
for revitalizing local economies and sustainable regional
development in rural communities especially inmountainous areas (Uragami & Itogami, 2007). In
addition, development of technologies such as small
biomass cogeneration systems for converting forest
resources into energy are being actively promoted (Japan
Woody Bioenergy Association, 2017a, b).
©2020 AIRES

228

T. TOGAWA et al.

Previous studies related to sustainable community
development in mountainous areas have been carried out
at the village or regional scale comprising single ormultiple local governments. Research at the village scale
has focused on specific energy projects and their impacts(Asano & Takaguchi, 2015). A number of studies at theregional scale have focused on regional circulation effectsof biomass and other resources (Sumitomo et al., 2015;
Miura et al., 2018; Nakamura & Shibata, 2013).
However, since these previous studies have been carriedout in parallel at each scale, inter-scale effects—for
example, the impact of village-scale energy systems on
resource circulation at a regional scale—have not beenadequately investigated.
Therefore, this study examined the feasibility oftransition to next-generation energy systems utilizing
local resources in mountainous villages of Japan, andquantified the impacts of introducing such systems on thebalance of resource supply and demand, as well as on theregional environment and socio-economy.

2. Study Area and Data
2.1 Study Area
This study targeted the central area of Mishima
Town in the Oku-Aizu area of Fukushima Prefecture.
According to the 2015 census, the population of Mishima
was 1,792, and the proportion of the population 65 orolder had already reached 49% (compared to the averagefor Japan of 26.6%). The main industries included
construction and electric power connected with a local
Tohoku Electric Power hydroelectric power plant(maximum output 94,000 kW), followed by agriculture,
forestry and tourism. The area of the town is 1,518 km2
with approximately 80% of that area being forested.
Therefore, regional development based on effective
utilization of woody biomass resources as energy has
become a goal of public policy. The use of woody
biomass resources, however, has been limited to theintroduction of wood pellet stoves and firewood stoves inForestWelfare facility

Prefectural
hospital

some public facilities and houses.
Figure 1 and Table 1 provide an outline of the study
area. The area inside the dotted line in Fig. 1 is the central
area of Mishima Town, which is the subject of this study.
Facilities such as the town hall, prefectural hospital, Aizu
Miyashita Station and welfare facilities are locatedcentrally and play a central role in the town. Solar panels
have been installed on the welfare facilities. Althoughhousing accounts for only a small proportion of buildingsin the central area of the town, that area has the town’slargest population concentration .
We estimated spatial information for the area thatwas required for energy system assessment. This included
the length of the heat distribution pipes that would be
required for deploying district heating and the area ofland where solar panels could be installed. The pipe
length was assumed to be the length of the shortest road
network required to connect the buildings in the area. It
was assumed that solar panels would be installed on theroofs of buildings in the central area of the town.
However, since roof area data were not available, thebuilt-up area was assumed to be the roof area. Building
data were estimated based on information from Zenrin
Tatemono Pointo (2014 version) and road network data
based on Zenrin Data Zmap-Town II (2015 version) using
GIS.
2.2 Establishing the Renewable Energy Supply
Potential
Since the renewable energy supply potential depends
on the characteristics of the region, we set assumptions
regarding the biomass resources and photovoltaic power
generation potential required for subsequent analysis. The
NEDO estimate (2011) for available biomass resources(forest residuals from harvesting and trimming) is 4,085
tons/year for Mishima Town and 43,746 tons/year if theresources of the four nearby towns and villages (Tadami
Town, Yanaizu Town, Kaneyama Town, and Showa
Village) in the Oku-Aizu area are included. This value isreferenced in the evaluation of the regional circularsphere. The photovoltaic power generation potential was
set based on monitoring data collected by the authors in
Mishima Town. Figure 2 shows the power generated by a
1 kW solar panel. The figure shows hourly data for one
week from January 1 to 7 as well as monthly data. The
Oku-Aizu region is a heavy-snowfall area that receives
approximately 60 cm of snow annually in the winter. The
Table 1 Overview of study area.

Town office

Aizu Miyashita
Station

ForestFig. 1 Study area (central district in Mishima Town).

No. of Households

Households

211

Population

Individuals390

Building Floor Area

2

[m ]

64,339Conduit Length

[m]

4,663

Roof Area[m ]32,2622

A study on sustainable energy systems for small villages in Fukushimaeffect of this snowfall is confirmed as reduction of power
generation during the winter months in Fig. 2. It is
assumed that the solar panels were covered with snow
from Jan 3 to 6. These data are referenced in subsequent
analyses as the potential amount of photovoltaic power
generation.

[kWh]

2.3 Energy Demand
Hourly energy demand data were set for the study
area for the following use categories: electric power,
cooling, heating and hot water supply. First, annual
energy demand was calculated by multiplying the floorarea for each use in each neighborhood by the energy
load intensity. Then, hourly energy demand was
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 1823

[kWh]

160
140
120
100
80
60
40
20
0

Oct

Noｖ

Dec

Jan

Feb

Mar

Apr

2017

May

Jan 6(Sat) Jan 7(Sun)

Jun

Jul

Aug

Sep

2018

Electricity

CoolingHea�ngHot water supply

Superstructure
Demand

3.5
3
2.5
2
1.5
1
0.5
0

3.1 Overview of the Planning Process Model
To examine the effect of introducing alternative
energy systems, it is necessary to evaluate detailed systemdesigns and optimal operation of each general system
type comparatively. In this study, the planning processmodel reported in previous studies (Togawa et al. 2017;
Togawa et al., 2020a) was used to determine theconditions resulting in minimal cost for design andoperation. The basic structure of the planning processmodel is shown in Fig. 4.
An energy system converts power supplied by thegrid or fuel from outside the system (gas, kerosene,
biomass resources, etc.) into electric power, heating andcooling, and hot water supply for use on the demand side.
First, we set up an energy system study framework.
Figure 4 shows a general structure including all candidate
energy systems that is referred to here as the

Supply[MWh]Fig. 2 Monitoring data of photovoltaic power
generation in the study area.
The upper graph for each case shows the hourly data (for one
week in January). The lower figure shows the monthly data.

0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 18
Jan 1(Mon) Jan 2(Tue) Jan 3(Wed) Jan 4(Thu) Jan 5(Fri)

CoolingHea�ngHot water supply

DemandElectricity

DesignJan 6(Sat) Jan 7(Sun)Supply[MWh]calculated by multiplying the annual energy demand by
the monthly and hourly proportions. The values reported
by Kashiwagi (2008) were used for the ratio of energy
load intensity and for monthly and hourly proportions; toreflect circumstances in the Tohoku region for energy
load intensity, we used the correction coefficient fromJapan District Heating & Cooling Association (2002).
Regarding the housing sector, the authors monitored
energy consumption at 12 all-electric homes in Mishima
for one year from October 2017 to September 2018.
Hourly and monthly electric power consumption wasmeasured by meters for each use category, and power
consumption for each use category was corrected using
the measurement results. Figure 3 shows the calculated
energy demand results (hourly values for the week ofJanuary 1 to 7 and monthly values for the year) for the
study area.

3. ModelJan 1(Mon) Jan 2(Tue) Jan 3(Wed) Jan 4(Thu) Jan 5(Fri)

Selected
Not selected

Operation
Noｖ
2017

Dec

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

2018

Fig. 3 Energy demand in study area.

The upper graph for each case shows the hourly data (for one
week in January). The lower figure shows the monthly data.

Sep

DemandOct

Supply

900
800
700
600
500
400
300
200
100
0

229

On status
Oﬀ status

t=1

t=2

Fig. 4 Basic structure of planning process model.

t=2016

230

T. TOGAWA et al.

“superstructure,” following the nomenclature used inprevious research (Yokoyama, 2014). The superstructure
is represented by the subsystems that represent thecandidate devices that make up the system and thepotential flows of energy between them (input/output
relationships).
Next, we simultaneously specified the system
configurations that minimize the cost function, which
combines flow values such as fuel consumption withstock values, such as installed capacity, and the operatingplans for each season and time period. Fuel consumption
was calculated by multiplying the energy demand of thebuildings shown in Fig. 3 by the energy conversion
efficiency of the equipment. Depending on the purpose, asubsystem can be selected from the superstructure, andthe equipment to be operated and the input/output levelfor operation can be specified for each season and time
for the selected equipment. For this reason, equipmentthat needs to be operated even once must be selected at
the design stage and the capacity of the equipment must
be greater than or equal to the annual maximum output
value.
However, for this study, because the calculation load
would be prohibitively high if the analysis were
performed for 8,760 hours a year, the calculations were
performed for 2,016 hours based on the data for one week
extracted from each month. It was also assumed that thesame type of energy system was installed in all thebuildings in the study neighborhood.

3.2 Establishing the Superstructures
Taking into consideration the availability ofresources and technological progress (Nakamura et al.,2018) in mountainous areas, we assessed the impact of
three different cases involving introduction of alternative
energy systems that combine biomass-related
technologies and photovoltaic power generation withthe currently deployed system. Figure 5 shows thesuperstructure of the system. Here, the energy systems
were treated as an aggregated unit for a givenneighborhood; the capacity of each component of theenergy systems could be set from continuous variables
except in the case of biomass cogeneration (BCHP:
Biomass Combined Heat and Power), which has arelatively large capacity per unit.
Case 1: Conventional System
Room air conditioners, kerosene heaters and gas
water heaters are used for cooling, heating, and hot watersupply, respectively. The energy supply sources are grid
power, kerosene, and LPG (liquefied propane gas).
According to survey results, this is the most common
system configuration in the study area (Nakamura et al.,2018).
Case 2: Photovoltaic Power Generation+ All-Electric System
All energy is supplied by the grid and solar panels.
Room air conditioners and heat pump water heaters areused for cooling, heating, and hot water supply. The
installation of storage batteries and heat storage tanks ispossible. As mentioned above, the maximum installation
Solar
batteries
Grid interconnection

Grid
Grid

Electricity
Air
conditioner
Kerosenestove
Gas waterheater

Kerosene
LPG
SourceElectricity

Storagebatteries

CoolingHeating

Sourcea) Case 1: Conventional System

HeatingHeat pump

Hot water

Consumer

Cooling

Air conditioner

Consumer

Hot water

Storagetankb) Case 2: Photovoltaic Power Generation+ All-Electric System

Solarbatteries
Grid

Grid interconnection

Storagebatteries
PelletSourceElectricity
Air conditioner
Pellet
Stove
Pelletboiler

CoolingHeating

Woody
Chips

BCHP
Storagetank

Hot water
SourceConsumerc) Case 3: Photovoltaic Power Generation

Absorption
chiller

District system

Air conditioner

Electricity
CoolingHeat
exchange

Heating
Hot water

Heat pipe

Consumerd) Case 4: Biomass Combined Heat and+ Biomass Heat Supply System
Fig. 5 Energy system alternatives.

Power System (BCHP)A study on sustainable energy systems for small villages in Fukushima

231

Table 2 BCHP unit parameter values.

Generation
System Type

Cost (1,000 JPY/Year)

Electric Power
OutputGeneration
Efficiency

ThermalEfficiency

Gasifier

45 kW

0.25

0.56

2,000

460

2,700

Gasifier

180 kW

0.30

0.45

22,000

5,900

2,700

ORC

600 kW

0.19

0.69

74,000

9,100

5,400

Capital Costs

Maintenance

Labor

Sources: Japan Woody Biomass Association (2017a, b), Nakagawa (2015), Bartenstein (2015).

area for solar panels equals the building roof area. In
recent years, all-electric houses, which are considered to
be one of the directions for future energy system
conversion, have been constructed in the study area
(Mishima Town, 2018).
Case 3: Photovoltaic Power Generation+ Biomass Heat Supply System
Although grid power and solar photovoltaic panels
are used as in Case 2, stoves and boilers that use biomasspellets as fuel are used for heating and hot water supply.
Given that the stoves and boilers are installed by eachcustomer, installation of heat distribution pipes is notnecessary. This scenario assumes the deployment to eachcustomer of photovoltaic power generation and biomass
heat supply systems that have already been installed insome buildings in the study area.
Case 4: Biomass Combined Heat and Power System(BCHP)The BCHP system generates the necessary electric
power and uses the waste heat for heating, cooling andhot water supply. Therefore, a heating pipe network is
required for the district. BCHP assumes the deploymentof a 10 to several hundred kW-class system similar to
those being developed mainly in Europe. The available
BCHP devices are shown in Table 2, with up to two units
being selectable for each system. This scenario proposes
the introduction of leading-edge technology of which
only a few examples exist in Japan.
The set values of other components required for eachenergy system were specified based on vendor catalogs,
and the unit prices for electricity, kerosene and LPG wereset based on the prices in the study area (Togawa et al.,2017).

4. Results
4.1 System Design and Operating Plans
Table 3 gives a summary of the system designs foreach case and lists the installed capacity of major
components of the energy systems shown in Fig. 5. First,
we confirmed the capacity of the solar photovoltaic
systems for Cases 2 and 3. In Case 2, a photovoltaic
system with a capacity equivalent to about 60% of theinstallable area (building roof area) was selected. The
capacity of the photovoltaic system in Case 3 was slightly
smaller than in Case 2 due to the lower electricity demand

Table 3 Summary of system components.

Case 1Case 2

Case 3

Case 4

Room Air Conditioner

(kW)

3,630

Kerosene Stove

(kW)

3,853

Gas Water Heater

(kW)

524

Photovoltaic Panels

(kW)

1,922

Room Air Conditioner

(kW)

3,630

Heat Pump Water Heater

(kW)

598

Photovoltaic Panels

(kW)

1,817

Pellet Heater

(kW)

3,853

Pellet Boiler

(kW)

475

BCHP

(kW)

870

Storage Batteries

(kWh)

5,359

Heat Exchange Unit

(kW)

6,380

for heating and hot water, which were covered by woodpellets instead. Next, we examined factors fordetermining the capacity of the pellet stoves and thepellet boilers in Case 3 by comparison with the demand
shown in Fig. 3. The installed capacity of the pellet stoves
was set at 3,853 kW, which corresponds to the peakheating demand in winter (January). For the week shownin Fig. 3, the peak heating demand was about 3,000 kW.
However, as the peak times for residential and businesssystems differ, the combined total of the peak heating
demands is about 3,853 kW. On the other hand, theinstalled capacity of the pellet boiler was set at 475 kW,
which is about half the peak demand for hot water supply
in winter (January) (about 800 kW for the week shown in
Fig. 3). Given the high cost of biomass boilers, it was
assumed that heat storage tanks would be installed to
optimize the systems and minimize boiler size.
4.2 Operating Plans
Next, to confirm how the systems operated, we
examined the energy supply and demand by hour andmonth (Fig. 6). The supply and demand data forelectricity and hot water for each case are presented. The
upper graph for each case shows the hourly data (for one
week in January) while the lower figure shows themonthly data. The equipment used to supply energy inresponse to demand is shown. Negative values for the
supply from storage batteries and hot water tanks in thehourly diagrams indicate energy is being stored. First,

232

T. TOGAWA et al.

Photovoltaic

Grid power

Electric power demand

Electricity supply and demand (Case 2)
Photovoltaic

Grid power

Electric power demand

Electricity supply and demand (Case 3)
BCHP

Storage battery

Electric power demand

Electricity supply and demand (Case 4)

Heat pump

Heat storage tank

Hot water demand

Hot water supply and demand (Case 2)
Pellet boiler

Heat storage tank

Hot water demand

Hot water supply and demand (Case 3)
BCHP

Heat storage tank

Hot water demand

Hot water supply and demand (Case 4)

Fig. 6 Supply and demand data for electricity and hot water in each case.

The upper graph for each case shows the hourly data (for one week in January). The lower figure shows the monthly data. Negative values forthe supply from storage batteries and hot water tanks in the hourly diagrams indicate energy is being stored.

A study on sustainable energy systems for small villages in Fukushima

-450

6,000
30

4,000
2,000

-2,000-4,000

Case1

Case2

Case3

Case4

0

-30

-6,000-8,000-60[million[million Yen]
Yen/year]0Fig. 8 
Results of evaluating CO2 emissions and the economic
value of these CO2 reductions.

Contribution to regional
economic circulation-400[million Yen/year]

60

8,000
2

4.3 Impacts of System Deployment
Figure 7 shows the results of estimating energy costs
for the entire study area for each case. The energy cost
including equipment associated with Case 1 wasapproximately 300 million JPY. The energy cost
reductions associated with Cases 2 and 3 were on theorder of 20%. However, Case 4 resulted in a 34%
increase in cost.
Next, we examined the effect of system deployment
on economic circulation. In Cases 1 and 2, most of theeconomic benefits are thought to flow out of the region.
The items that are likely to contribute to regional
economic circulation (personnel costs, maintenance costs,
pellet charges, chip charges) amounted to 52 million JPY
for Case 3 and 175 million JPY for Case 4. These costs
only accounted for approximately 1% in Case 3 and 3%
in Case 4 of Mishima Town’s total production, which is
6.1 billion JPY (Ministry of the Environment & ValueManagement Institute, 2013). These results indicate theimportance of expanding measures beyond the central
area to the surrounding areas if they are to have an impact
on revitalizing the regional economy.
Figure 8 shows the impact of each case on CO2emissions and emissions reduction. Cases 2 and 3
reduced CO2 emissions by 28% and 43%, respectively,
compared to Case 1. In Case 4, CO2 emissions were zero
because energy from fossil fuels was not used. Using a
CO2 transaction price of 4,355 to 8,710 JPY/ton-CO2(40 to 80 USD/ton-CO2) from the World Bank (2019), theeconomic value of these CO2 reductions is estimated tobe 6 to 47 million JPY. In all cases, the value is about
10% to 40% compared to the increase/decrease in directenergy costs, indicating the importance of taking thevalue of environmental benefits into account whenselecting energy systems.
Next, we examined the consumption of biomass
resources. Here, the amount of woody biomass resources
used as raw materials was evaluated in a unified manner.
We assumed that both pellets and chips were produced
from woody biomass resources with a moisture content
of 50%, which is equivalent to that of raw wood, andconverted biomass mass into energy units assuming 1 kg
= 2.33 kWh. The results are shown in Fig. 9 together withthe available woody biomass resources in Mishima Town.
In Case 3, the consumption of biomass resources wasapproximately 40% of the amount available to Mishima[ton-CO2/year]][ton-CO

from the electric power supply and demand for Cases 2
and 3, it can be seen that photovoltaic power generation
exhibits substantial seasonal and daily fluctuations, withthe amount of power generation in winter being
particularly limited. Furthermore, from the hourly supply
and demand for hot water supply in Case 2, it can be seenthat the heat pump water heater is operated using lowcost nighttime electricity. In addition, from the hourly
supply and demand for hot water supply in Case 3, it isevident that hot water is stored during the low-demand
period with the 475 kW biomass boiler operating at full
capacity, which is lower than the peak demand; the stored
hot water is consumed during the peak demand period in
the evening. Similarly, from the results for Case 4, it canbe seen that the BCHP system operates steadily at
870 kW throughout the year, storing surplus electricity atnight when demand is low and distributing the stored
electricity during peak daytime demand periods when the
BCHP system output is lower than demand. As above,
appropriate system designs and operating plans were
derived for each case.

233

-350
-300
-250
-200
-150
-100
-50
0

Case1

Case2

Case3

Case4

Deprecia�onDepreciation
Deprecia�on(plumbing)(Distribution pipes)

Maintenance fee

Labor costs

Electricity charges

Gas charges

Kerosene charge

Pellet fee

Chip fee

Fig. 7 Cost evaluation results.

Fig. 9 Results of evaluating biomass resource consumption.

234

T. TOGAWA et al.

Town, while the consumption in Case 4 greatly exceededavailable resources. However, in all cases, the amountconsumed was small compared to the total annual
biomass resources available in the Oku-Aizu area
(48,736 tons/year according to NEDO, 2011). Thus, we
believe that the use of biomass energy can contribute torevitalization of forestry in Mishima Town and the OkuAizu area.

5. Discussion
As shown in Fig.7, we found that it would be
difficult to introduce neighborhood energy systems basedon BCHP due to the substantial initial investment
associated with neighborhood BCHP systems. However,the system is expected to have a positive regional effect(Figs. 8 and 9). Also, these results are based on thecurrent socio-economic situation. It is important to take
into consideration that technological development ofsmall-scale energy supply systems suitable forneighborhood energy systems is actively progressing(Murugan & Horák, 2016). In particular, small 10 kWclass biomass cogeneration system units have beendeveloped and are being deployed mainly in Europe. In
Japan, studies have been carried out addressing
component technologies related to biomass power
generation. Yanagida et al. (2015) analyzed therelationship between the break-even point and raw
material procurement cost for biomass power generation
businesses at various output scales. They found that, even
if a relatively high feed-in-tariff purchase price isassumed, the amount of power generated must be 5 MW
or greater to be profitable. Sasauchi (2015) examined thetechnical characteristics of steam turbine power
generation, gasification with gas engine power
generation, and ORC (Organic Rankine Cycle) power
generation, which are typical power generation methods
for woody biomass, and reviewed the profitability ofsmall-scale projects for each method. They found that thesteam turbine method is not profitable for small-scale
power generation businesses of about 2 MW. However,profitability is greatly improved for gasification with gas
engine power generation and ORC power generation,
which can supply heat along with power, indicating thebusiness potential of such systems. Similarly, Kuboyama
et al. (2016) and Komata et al. (2016) point out the needfor cogeneration when using small-scale biomass
generators. As described above, technologies for practical
distributed energy systems that can contribute to local
economies by utilizing forest resources in mountainous
areas are being developed. The output of the 870 kW
BCHP examined in this study was less than half that of
the 2 MW-class systems evaluated in the above studies.
Moreover, as can be seen from Fig. 6, the efficiency ofheat utilization is not always high. These points alongwith those mentioned above indicate that increasing

demand and improving heat utilization efficiency arechallenges that must be overcome.
Based on the above, the key to implementing local
energy systems is improving energy utilization efficiency
through cogeneration. However, as the ability to transport
thermal energy is limited, efforts must be integrated with
regional development plans that include, for example,
concentrating energy consumers. In a previous study(Shirai, 2018b) field studies were conducted in eightpioneering examples of integrated energy business andcommunity development, clarifying the roles played bystakeholders such as local companies, citizen networks,
regional organizations and universities. It has also been
pointed out that these examples are not based on topdown deployment but, rather, the result of co-creative
processes by diverse stakeholders in a community. A casestudy conducted by the authors in Shiwa Town, Iwate
Prefecture, which is an environmentally leading
municipality, found that budding efforts in resource
circulation that started around 2000 have spawned otheractivities including the development of various spaces by
diverse stakeholders through co-creative processes(Togawa et al., 2020b). These results show that to create
sustainable communities based on renewable energy inrural areas with low population density, it is important tointegrate energy system development with community
development from a medium- to long-term perspective.
However, no general design schemes that can be applied
to different complex problems have been sufficiently
developed, and past approaches have tended to rely on
local experience. In our research as well, we examined a
top-down method for designing a distributed energy
system. Frameworks for bottom-up design of sustainablecommunities that complement this top-down approachneed to be developed.
In addition, various social benefits associated with
deployment of distributed systems have also been
identified. These include the stabilization of employment
by building energy supply systems in local communities,
enhanced continuity of the energy supply in the event of
a disaster, and improved safety and security of the region(Nakata 2015). Therefore, it is important to develop
systems that are competitive in function with large scale
systems while also being tailored to the unique
circumstances of each community through co-creative
processes and multidimensional perspectives that cover
the environment, economy and society.

6. Conclusions
In this study, we developed designs and operatingplans for and evaluated the deployment potential of
alternative energy systems taking into account thestructure of the neighborhoods that made up the area andthe supply characteristics of renewable energy. Ourfindings were as follows:A study on sustainable energy systems for small villages in Fukushima● Based on hourly energy supply and demand, wedeveloped a planning process model that cansimultaneously derive optimal energy system design andoperating plans and conducted analyses using dataobtained through monitoring in the actual community.
● We conducted analyses using models based on
information that we had obtained for the central area ofMishima Town, Fukushima Prefecture, which has
characteristics typical of the mountainous areas of Japan.
Our results showed that it is possible to reduce energy
costs by introducing a fully electrified system that uses
photovoltaic power generation. We also showed that the
introduction of biomass boilers and biomass cogeneration
systems that utilize forest biomass resources is desirablefrom the perspective of CO2 emissions reduction andlocal resource circulation.
● We considered issues for implementation ofregional energy systems in rural areas with low
population densities. We found that a framework wasnecessary for comprehensively designing sustainablelocal communities that incorporates regional developmentin the surrounding area with selection of appropriate
distributed energy systems that are tailored to regional
characteristics.
References
Asano, H. and Takaguchi, H. (2015) Research on the planning ofvillage that self-sufficient in energy on the time of aggregationin Kumano, Mie: Proposal for the planning of village that selfsufficient in energy in semimountainous area. Technical Papersof Annual Meeting the Society of Heating, Air-conditioning andSanitary Engineers of Japan, 10, 233–236. (in Japanese)
Bartenstein, O. (2015) Spanner wood cogeneration plant. Journalof the Japan Institute of Energy, 94(11), 1198–1203. (inJapanese)Japan District Heating & Cooling Association (2002) District
Heating and Cooling Technical Guidebook, Revised Edition,
Tokyo. (in Japanese)
Japan Woody Bioenergy Association (2017a) Overseas Survey ofSupport Measures for Deployment of Small-scale Woody
Bioenergy for Combined Heat and Power. (in Japanese)
Japan Woody Biomass Association (2017b) Overseas Survey on
Support Policies for Small-scale Woody Biomass Power
Generation/Combined Heat and Power Introduction. (inJapanese)
Kashiwagi, T. (2008) The Japan Institute of Energy: Natural Gas
Cogeneration Planning and Design Manual, Japan Industrial
Publishing Co., Ltd., Tokyo. (in Japanese)
Komata, H., Maeda, N., Ishikawa, Y., Yanagida, T., Kuboyama, H.
and Hondo, H. (2016) O-8 risk analysis for economic impact ofpower generation business and CHP generation business bywooden biomass. Proceedings of the Conference on Biomass
Science, 11, 15–16. (in Japanese)
Kuboyama, H., Furumata, H. and Yanagida, T. (2016) Possibilities
on small/medium scale wood biomass power production. The
Japanese Forest Society Congress, 127, 678. (in Japanese)
Ministry of the Environment and Value Management Institute(2013) RESAS: Regional Economy Society Analyzing System. (inJapanese) Retrieved from https://resas.go.jp/regioncycle/#/map/
7/07444/2/2013 (Accessed 27 December 2020)

235

Mishima Town (2018) Koho Mishima, No. 289. (in Japanese)
Retrieved from http://www.town.mishima.fukushima.jp/wpcontent/uploads/2017/04/0f07d76fbc500c8a8f3f3bc0374d394d.
pdf (Accessed 27 December 2020)
Miura, A., Endo M., Itoh, S. and Kayo, C. (2018) Regional
economic impacts of wood fuel production. Wood Industry,73(1), 13–19.(in Japanese)
Murugan, S. and Horák, B. (2016) A review of micro combined
heat and power systems for residential applications. Renewable
and Sustainable Energy Reviews, 64, 144–162.
Nakagawa, H. (2015) Small scale CHP systems manufactured byburkhardt and volter. Journal of the Japan Institute of Energy,
94 (11), 1194–1197. (in Japanese)
Nakamura, R. and Shibata, H. (2013) Contributions to regional
economies by wooden biomass usage. Okayama Economic
Review, 45(1), 19–31. (in Japanese)
Nakamura, S., Oba. M., Nemoto, K. and Mori, Y. (2018) Use ofwoody biomass of household in hilly and mountainous areas.
The Japanese Forest Society Congress, 129, 809.
Nakata, T. (2015) Building autonomous, distributed energy systems
in disaster-stricken areas: how to design local communities.
Research on Environmental Disruption, 44 (3), 34–40. (inJapanese)
NEDO (2011) Estimate of Biomass Resources and Usable Reserve.
(in Japanese)
Sasauchi K. (2015) Selection of technical systems suitable forsmall scale biomass power generation under the FIT scheme.
Journal of the Japan Institute of Energy, 94(11), 1188–1193. (inJapanese)
Shigeto, S., Arita, A., Moriyama, Y. and Fujiyama, K. (2018)
Possibility for creation and promotion of regional circular andecological spheres. Review of Environmental Economics andPolicy Studies, 11 (2), 69–73. (in Japanese)
Shirai, N. (2018a) Towards regional development throughrenewable energy. Review of Environmental Economics andPolicy Studies, 11 (2), 78–82. (in Japanese)
Shirai, N. (2018b) Regional development through renewableenergy. The Environmental News, Tokyo. (in Japanese)
Sumitomo, Y., Furabayashi, T. and Nakata, T. (2015) Design ofdistrict heating system in rural area considering biomass resourceand energy demand distribution. Journal of Japan Society ofEnergy and Resources, 36(5), 1–11. (in Japanese)
Togawa, T, Dou, Y., Oba, M., Nemoto, K., Nakamura, S. and Fujii,
M. (2017) Design and standards for distributed energy system inmountainous areas. Journal of Japan Society of Civil Engineers
G (Environment), 73(5), I_107–I_119. (in Japanese)
Togawa, T., Nakamura, S., Oba, M., Nemoto K., Dou, Y. and Fujii,
M. (2020a) Design of distributed energy system consideringvillage structure and regional circulation symbiosis in a
mountainous area. Journal of Japan Society of Civil Engineers
G (Environment), 76. (in Japanese)
Togawa, T., Ohnish,i S. and Fukushima, H. (2020b) Description of
the co-creative process found in leading cities for environmental
and community development. Japan Society of Civil Engineers
Infrastructure and Planning and Management Fall Meeting
Proceedings, 62. (in Japanese)
Uragami, K. and Itonaga, K. (2007) View of sustainable ruralplanning by local production for local consumption of the forest
bioenergy-case of plan for the local production for local
consumption in Iitate Village: Case of plan for the local
production for local consumption in Iitate Village. Journal of
Rural Planning Association, 26 (3), 153–158. (in Japanese)
World Bank (2019) State and Trends of Carbon Pricing 2019.
Yanagida, T., Yoshida, T., Kuboyama, H. and Jinkawa, M. (2015)
Relationship between feedstock price and break-even point of

236

T. TOGAWA et al.

woody biomass power generation under FIT program. Journal of
the Japan Institute of Energy, 94(3), 311–320. (in Japanese)
Yokoyama, R. (2014) Optimal design of distributed energy systems:focusing on approach in consideration of hierarchicalrelationship between design and operation. Proceedings of theTwenty-Sixth RAMP Symposium, 85–98. (in Japanese)

Takuya TOGAWA
Takuya Togawa is a senior researcher at the
National Institute for Environmental Studies,
Fukushima Branch. He received his doctorate inengineering from the Graduate School ofEnvironmental Studies, Nagoya University in2010. He is engaged in research on mechanisms
for realizing disaster recovery and regional
revitalization by effectively utilizing local environmental resources.

Yi DOUYi Dou is a project researcher for the Presidential
Endowed Chair for “Platinum Society,”
University of Tokyo. He received his doctorate
in engineering from Nagoya University in 2019,and his research interests are closely related tourban sustainable development, especially
focusing on promoting circular economies andproliferation of emerging technologies through regional energy planning.

Shogo NAKAMURA
Shogo Nakamura is a researcher in the Regional
Environmental Renovation Section of the
National Institute for Environmental Studies,
Fukushima Branch. He holds a Ph.D. inagricultural science. He has played a central rolein developing the energy monitoring systems in
Shinchi as well as many other areas in
Fukushima. Recently his interests have led him to participate in theEnvironment-Economy-Society Integration Research program.

Makoto OOBA
Dr. Ooba heads the Environmental Renovation
Laboratory at the Fukushima Branch of the
National Institute for Environmental Studies,Japan. From 2007 to 2012 and from 2014 to thepresent, he has participated in a study on spatialassessment of Japan’s regional forests using
process-based models and remote sensing by
NIES. Based on these studies, he has analyzed sustainability of forestry andharvested wood products. He has also worked at Osaka University, Nagoya
University and the Tokyo University of Agriculture. He holds a Ph.D. inenvironmental science from Hokkaido University, 2002.
(Received 2 December 2020, Accepted 27 December 2020)