Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1371/journal.pclm.0000318

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.oneear.2023.06.005

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Scopus

Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.2208/jscejj.22-00270

Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

<p> This study simulated energy systems that could achieve carbon neutrality in 2050 for Kushiro City, Hokkaido, Japan, using an energy system model which can take into account the use of synthetic fuels and regional characteristics. The results show that a scenario with no emission reduction targets could reduce CO₂ emissions by 61% from 2015 levels, and even a scenario without synthetic fuels could reduce emissions by 80% from 2015 levels through aggressive mitigation measures. Key mitigation measures in the mitigation scenario included the introduction of solar photovoltaics in the residential sector, the substitution to LP gas in the industrial sector, and the promotion of electrification in the transportation sector. The study also showed that carbon neutrality in 2050 could be achieved by using synthetic fuels to meet the energy demand that should be supplied by liquid and gaseous fuels, i.e., space heating in the cold region and industrial heat. Policies that encourage the cost reduction of synthetic fuels are key to decarbonizing cold regions and industrial clusters, where the demand for liquid and gaseous fuels may remain.</p>

DOI： 10.2208/jscejj.23-27038

CiNii Research

DOI： 10.21203/rs.3.rs-2050486/v1

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：Sustainability Science  

In the original publication of the article, data availability was missing and it is provided in this correction. The scenario data is available at https:// doi. org/ 10. 5281/ zenodo. 48176 56.

DOI： 10.1007/s11625-021-00992-1

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Scopus

Language：English   Publisher：Sustainability Science  

© 2021, The Author(s). In the original publication of the article, the incorrect file was published as supplementary material. The supplementary file “Supplementary file1” has been replaced. The original article has been updated.

DOI： 10.1007/s11625-021-00934-x

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Sustainability Science  

© 2021, The Author(s). The Japanese power system has unique characteristics with regard to variable renewable energies (VREs), such as higher costs, lower potentials, and less flexibility with the grid connection compared to other major greenhouse-gas-emitting countries. We analyzed the role of renewable energies (REs) in the future Japanese power sector using the results from the model intercomparison project Energy Modeling Forum (EMF) 35 Japan Model Intercomparison Project (JMIP) using varying emission reduction targets and key technological conditions across scenarios. We considered the uncertainties for future capital costs of solar photovoltaics, wind turbines, and batteries in addition to the availability of nuclear and carbon dioxide capture and storage. The results show that REs supply more than 40% of electricity in most of the technology sensitivity scenarios (median 51.0%) when assuming an 80% emission reduction in 2050. The results (excluding scenarios that assume the continuous growth of nuclear power and/or the abundant availability of domestic biomass and carbon-free hydrogen) show that the median VRE shares reach 52.2% in 2050 in the 80% emission reduction scenario. On the contrary, the availability of newly constructed nuclear power, affordable biomass, and carbon-free hydrogen can reduce dependence on VREs to less than 20%. The policy costs were much more sensitive to the capital costs and resource potential of VREs than the battery cost uncertainties. Specifically, while the doubled capital costs of VRE resulted in a 13.0% (inter-model median) increase in the policy cost, the halved capital costs of VREs reduced 8.7% (inter-model median) of the total policy cost. These results imply that lowering the capital costs of VREs would be effective in achieving a long-term emission reduction target considering the current high Japanese VRE costs.

DOI： 10.1007/s11625-021-00917-y

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Sustainability Science  

© 2021, The Author(s). In June, 2019, Japan submitted its mid-century strategy to the United Nations Framework Convention on Climate Change and pledged 80% emissions cuts by 2050. The strategy has not gone through a systematic analysis, however. The present study, Stanford Energy Modeling Forum (EMF) 35 Japan Model Intercomparison project (JMIP), employs five energy-economic and integrated assessment models to evaluate the nationally determined contribution and mid-century strategy of Japan. EMF 35 JMIP conducts a suite of sensitivity analyses on dimensions including emissions constraints, technology availability, and demand projections. The results confirm that Japan needs to deploy all of its mitigation strategies at a substantial scale, including energy efficiency, electricity decarbonization, and end-use electrification. Moreover, they suggest that with the absence of structural changes in the economy, heavy industries will be one of the hardest to decarbonize. Partitioning of the sum of squares based on a two-way analysis of variance (ANOVA) reconfirms that mitigation strategies, such as energy efficiency and electrification, are fairly robust across models and scenarios, but that the cost metrics are uncertain. There is a wide gap of policy strength and breadth between the current policy instruments and those suggested by the models. Japan should strengthen its climate action in all aspects of society and economy to achieve its long-term target.

DOI： 10.1007/s11625-021-00913-2

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Scopus

PubMed

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Climatic Change  

© 2020, Springer Nature B.V. With the shift of climate debate from understanding to actions, the use of integrated assessment models (IAMs) is gradually expanding. Since IAMs produce least-cost pathways, technoeconomic parameters constitute one of the basic parameters. Traditionally, IAMs dealt with technologies with slowly-changing, relatively homogeneous manner. Since technologies are rapidly evolving, and the pattern of technological development is regionally heterogeneous, the IAM community must embrace a new strategy to treat their underlying technoeconomic parameters. Here we illustrate such challenges by reviewing the treatment and performance of IAMs with respect to some of the rapidly changing technologies (e.g., solar, wind, and batteries). Our review shows that IAMs have difficulty in updating the cost of the rapidly changing technologies. We then articulate a new strategy, drawing upon the lesson from the current model intercomparison projects and climate sciences. We argue that a loose network of modeling groups across the globe should create a database of technological parameters in a standardized format and standard evaluation tool, perhaps to be facilitated by the IAM Consortium. Such a framework would contribute to the review of the progress toward the Paris Agreement goals.

DOI： 10.1007/s10584-020-02731-4

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

© 2019 Elsevier Ltd The road transport sector accounted for 18.8% of global CO2 emissions in 2016. Regional efforts are indispensable for reducing automobile emissions, especially considering the diversity in regional transportation systems. Existing studies of automobile emissions have focused on nationwide transportation systems or differences in city size without considering regionality and long-term changes in vehicle occupancy. In this study, we decomposed national and regional automobile emissions in Japan between 1990 and 2015 by the Logarithmic Mean Divisia Index method. Statistical data that took vehicle occupancy into account were used. Results showed that nationwide vehicle occupancy increased (due to increased vehicle size and vehicle ownership), which increased emissions by 15.2% compared to 1990 levels. In highly populated regions, fuel efficiency decreased earlier than other regions thanks to the strengthening of ordinances regarding air pollution. In Western Japan, which includes less-populated prefectures, the rising popularity of mini-vehicles resulted in increased vehicle ownership and a decrease in occupancy but also led to improvements in fuel economy. To reduce automobile CO2 emissions, it will be essential to improve fuel efficiency and to increase vehicle occupancy through mechanisms, such as ridesharing and vehicle right sizing.

DOI： 10.1016/j.apenergy.2019.114196

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Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Nature Communications  

© 2019, The Author(s). The costs of climate change mitigation policy are one of the main concerns in decarbonizing the economy. The macroeconomic and sectoral implications of policy interventions are typically estimated by economic models, which tend be higher than the additional energy system costs projected by energy system models. Here, we show the extent to which policy costs can be lower than those from conventional economic models by integrating an energy system and an economic model, applying Japan’s mid-century climate mitigation target. The GDP losses estimated with the integrated model were significantly lower than those in the conventional economic model by more than 50% in 2050. The representation of industry and service sector energy consumption is the main factor causing these differences. Our findings suggest that this type of integrated approach would contribute new insights by providing improved estimates of GDP losses, which can be critical information for setting national climate policies.

DOI： 10.1038/s41467-019-12730-4

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Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Energy  

© 2018 The Authors Japan is the sixth largest greenhouse gas emitter in 2016 and plays an important role to attain the long-term climate goals of the Paris Agreement. One of the key policy issues in Japan's energy and environmental policy arena is the energy system transition to achieve 80% emissions reduction in 2050, a current policy goal set in 2016. To contribute to the ongoing policy debate, this paper focuses on energy-related CO 2 emissions and analyzes such decarbonization scenarios that are consistent with the government goals. We employ six energy-economic and integrated assessment models to reveal decarbonization challenges in the energy system. The modeling results show that Japan's mitigation scenarios are characterized by high marginal costs of abatement. They also suggest that the industrial sector is likely to have a large final energy share and significant residual emissions under the 80% reduction scenario, though it is generally thought that the transport sector would have large decarbonization challenges. The present findings imply that not only energy policy but also industrial policy may be relevant to the long-term environmental target. Given the high marginal costs exceeding those of negative emissions technologies that could place a cost ceiling, further model development would be crucial.

DOI： 10.1016/j.energy.2018.10.091

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DOI： 10.5547/01956574.40.SI1.kmat

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Applied Energy  

© 2018 Elsevier Ltd This study investigated insights into reducing energy-related CO2 emissions in households by examining individual socio-economic drivers at a sub-national level. Specifically, the logarithmic mean Divisia index technique was used to decompose CO2 emission trends into six drivers in all 47 prefectures of Japan during the period from 1990 to 2015. Drivers included the change in the number of households (household effect), distribution of households (distribution effect), household size (size effect), per-capita household energy consumption (consumption effect), household energy choice (choice effect), and sectoral CO2 emission intensity (intensity effect). The results showed that, in contrast to size and the distribution effects, the number of households had a positive, significant effect on CO2 emissions, indicating that recent demographic trends are responsible for the increase in CO2 emissions observed in most of the prefectures during the study period. With regard to effects related to consumption and choice, CO2 emissions due to changes in lifestyle dropped in only seven prefectures and reductions due to changes in sectoral energy choice were seen in only two prefectures in 2015. The intensity effect boosted the emissions of these prefectures the most in 2015 because of the shutdown of nuclear power plants due to the Great East Japan Earthquake. Further, we identified those prefectures that needed to reduce their per-capita energy consumption level in order to attain the reduction targets for household CO2 emissions in 2030 from 2015, given projected changes in demographic trends and recent and projected emission intensities. In order to achieve reductions in total CO2 emissions in line with the Paris Agreement, it is important to prioritize national and local policy interventions for the transfer of new household energy technologies, upgrade household appliances, and encourage people to limit energy consumption in light of the differences in these key drivers in each prefecture.

DOI： 10.1016/j.apenergy.2018.07.057

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Renewable and Sustainable Energy Reviews  

© 2018 Elsevier Ltd A secure energy supply is indispensable for Japan's economic activity, but it is becoming more difficult to attain, due to increasing energy demand in emerging countries. The pattern of socioeconomic development and the achievement of a low-carbon society are also strongly related to energy security. This study evaluated energy security performance in Japan under alternative scenarios of future socioeconomic and energy conditions by applying three energy security indicators derived from the Shannon-Wiener diversity index. The 2050 Japan Low Carbon Navigator was used to estimate energy structures under five socioeconomic scenarios and three selected combinations of effort levels toward producing a low-carbon society. It was found that the effort levels were the most influential factors in determining energy security performance, because they greatly affect energy supply and demand. The choice of socioeconomic scenario was also influential, although the impact of this choice was less significant than the choice of effort level. However, the impact of country-risk indicators is less substantial than the above two factors. The energy security performance of Japan will improve in the future, compared with the current level. However, if the country pursues further economic growth, its energy security performance will not greatly improve. Consequently, increasing efforts to achieve a low-carbon society will contribute to the realization of a highly energy-secure society with respect to Japan's current and future socioeconomic situation.

DOI： 10.1016/j.rser.2018.03.070

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Scopus

Language：English   Publisher：PLoS ONE  

After the severe nuclear disaster in Fukushima, which was triggered by the Great East Japan earthquake in March 2011, nuclear power plants in Japan were temporarily shut down for mandatory inspections. To prevent large-scale blackouts, the Japanese government requested companies and households to reduce electricity consumption in summer and winter. It is reported that the domestic electricity demand had a structural decrease because of the electricity conservation effect (ECE). However, quantitative analysis of the ECE is not sufficient, and especially time variation of the ECE remains unclear. Understanding the ECE is important because Japan’s NDC (nationally determined contribution) assumes the reduction of CO2 emissions through aggressive energy conservation. In this study, we develop a time series model of monthly electricity demand in Japan and estimate time variation of the ECE. Moreover, we evaluate the impact of electricity conservation on CO2 emissions from power plants. The dynamic linear model is used to separate the ECE from the effects of other irrelevant factors (e.g. air temperature, economic production, and electricity price). Our result clearly shows that consumers’ electricity conservation behavior after the earthquake was not temporary but became established as a habit. Between March 2011 and March 2016, the ECE on industrial electricity demand ranged from 3.9% to 5.4%, and the ECE on residential electricity demand ranged from 1.6% to 7.6%. The ECE on the total electricity demand was estimated at 3.2%–6.0%. We found a seasonal pattern that the residential ECE in summer is higher than that in winter. The emissions increase from the shutdown of nuclear power plants was mitigated by electricity conservation. The emissions reduction effect was estimated at 0.82 MtCO2–2.26 MtCO2 (−4.5% on average compared to the zero-ECE case). The time-varying ECE is necessary for predicting Japan’s electricity demand and CO2 emissions after the earthquake.

DOI： 10.1371/journal.pone.0196331

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PubMed

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：公益社団法人 土木学会  

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：公益社団法人 土木学会  

Language：English   Publishing type：Research paper (scientific journal)  

Publisher：Energy Economics  

The curtailment and storage associated with the fluctuation of electricity supplied by variable renewable energy (VRE) may limit its penetration into electricity systems. Therefore, these factors need to be explicitly treated in the integrated assessment models (IAMs). This study improves the representation of curtailment and storage of VRE in a computable general equilibrium (CGE) model. With the data generated from an hourly power sector model, curtailment and storage of VRE electricity are treated as a function of the shares of solar and wind in the electricity mix. This relationship is incorporated into a CGE model and we also updated the VRE costs and resource potential. The results show that with such improvement, by 2100, in a 450 ppm atmospheric CO2 equivalent concentration (henceforth ppm) scenario, some electricity generated from VRE is either curtailed (2.1%) or needs to be stored (2.9%). In contrast, if VRE fluctuation is not considered, the long-term global economic cost of carbon mitigation is significantly underestimated (by 52%) in the same scenario. Conversely, updating the VRE costs and resource potential leads to a decrease in mitigation costs. Our simulation implies that the fluctuation of VRE cannot be ignored and needs to be incorporated into CGE models. Moreover, in addition to storage with batteries, many other options are available to reduce curtailment of VRE. The top-down type CGE model has limitations to fully incorporate all aspects due to its limited spatial, temporal, and technological resolution.

DOI： 10.1016/j.eneco.2016.03.002

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.energy.2016.08.019

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Scopus

Publisher：Journal of Cleaner Production  

Power plants are one of key energy sources for industrial symbiosis complexes. However, decarbonization of the power sector, including decommissioning of existing fossil-fuel power plants, aggregation of power plant sites, and capacity augmentation of carbon-free power plants, is necessary to achieve low-carbon societies in the long term. Decarbonization results in declining advantage for industrial symbiosis complexes that rely on fossil-fuel power plants. To establish sustainable industrial symbiosis complexes, we used a quantitative model to analyze optimal locations and scales for power plants in Japan considering CO2 emissions reduction targets and several demand scenarios. Our results showed that even with a target of 80% CO2 emission reduction, almost half of Japan's electricity generation could come from fossil-fuel power plants in 2050 if CCS technology were deployed widely. Fossil-fuel power plants would be developed mainly in the regions of high electricity demand and little wind power potential, such as Tokyo, Chubu, and Kansai. From an intra-regional perspective, fossil-fuel power plants could be constructed in areas of high electricity demand. In addition, except for the above areas, generation from fossil-fuel power plants would vary in accordance with the availability of renewables and electricity demand. Our results indicate that future climate policy, regional electricity demand, and availability of regional renewables should be considered when planning the development of industrial symbiosis complexes.

DOI： 10.1016/j.jclepro.2015.09.079

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Scopus

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：The Japan Institute of Energy  

In order to achieve long-term GHG reduction target in Japan (80% reduction from 1990 level), it is important to take actions in national scale as well as sub-national (or local) scale, such as municipalities. However, due to lack of basic information of energy supply and consumption in sub-national scale, designing low carbon society scenarios faces many difficulties to proceed. In the paper, we have analyzed energy supply and consumption structure and summarized as an Energy Balance Table (EBT), and investigate future trend and feasibility of achieving low carbon society in sub-national scale. So-so area of Fukushima prefecture is selected as a target area. It is found from the results that trend of energy supply and consumption in sub-national scale is totally different from national scale trend.

DOI： 10.20550/jietaikaiyoushi.23.0_302

CiNii Books

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2024.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：東京   Country：Japan  

Event date： 2024.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2024.8

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2024.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2024.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：滋賀   Country：Japan  

Event date： 2023.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪   Country：Japan  

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Poster presentation  

Venue：Ibaraki  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪  

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

Audience： College students

Type：Visiting lecture

Audience： College students,　Graduate students,　General

Type：Lecture

Type：Academic society, research group, etc.