Updated on 2022/05/17

写真a

 
JU, Yiyi
 
Affiliation
Affiliated organization, Waseda Institute for Advanced Study
Job title
Assistant Professor(non-tenure-track)

Concurrent Post

  • Faculty of Social Sciences   School of Social Sciences

  • Faculty of International Research and Education   Graduate School of Asia Pacific Studies

Education

  • 2016.10
    -
    2019.09

    Nagoya University   Graduate School of International Development   Doctor of Philosophy (International Development)  

Research Experience

  • 2021.04
    -
    Now

    Waseda University   Institue for Advanced Study   Assistant professor

  • 2020.11
    -
    2021.03

    The University of Tokyo

  • 2019.10
    -
    2020.10

    The University of Tokyo

Professional Memberships

  • 2020.04
    -
    Now

    エネルギー・資源学会

  • 2017.04
    -
    Now

    Pan Pacific Association of Input-Output Studies (PAPAIOS)

  • 2017.04
    -
    Now

    Society for Environmental Economics and Policy Studies (SEEPS)

 

Research Areas

  • Environmental policy and social systems

Research Interests

  • Industrial decarbonization

  • Energy-economic and integrated assessment models

  • Climate policy instruments

Papers

  • An open-source tool for visualization of climate mitigation scenarios: Mipplot

    Yiyi Ju, Masahiro Sugiyama, Diego Silva Herran, Jiayang Wang, Akimitsu Inoue

    Environmental Modelling & Software   139   105001 - 105001  2021.05  [Refereed]

    Authorship:Lead author

     View Summary

    Synthesizing and communicating knowledge on climate change to policymakers and stakeholders is often difficult due to the complexity and diversity of underlying research. As a “translation” instrument, we present the mipplot tool, an open-source R package that can be used to visualize data of long-term climate mitigation scenarios. With simple commands and under a user-friendly language platform, this tool generates plots in multiple languages for any scenario dataset following the data submission format of the Integrated Assessment Modeling Consortium. The plots can be generated both by function call in R environment and by an interactive interface in a web browser environment, which offers greater flexibility of inputs and suits both experts and non-experts. Moreover, its capability of specifying aggregation rules and different display languages extends its applicability to a broader range of users.

    DOI

  • Industrial decarbonization under Japan’s national mitigation scenarios: a multi-model analysis

    Yiyi Ju, Masahiro Sugiyama, Etsushi Kato, Yuhji Matsuo, Ken Oshiro, Diego Silva Herran

    Sustainability Science   16 ( 2 ) 411 - 427  2021  [Refereed]

    Authorship:Lead author

     View Summary

    Energy-intensive industries are difficult to decarbonize. They present a major challenge to the emerging countries that are currently in the midst of rapid industrialization and urbanization. This is also applicable to Japan, a developed economy, which retains a large presence in heavy industries compared to other developed economies. In this paper, the results obtained from four energy-economic and integrated assessment models were utilized to explore climate mitigation scenarios of Japan’s industries by 2050. The results reveal that: (i) Japan’s share of emissions from industries may increase by 2050, highlighting the difficulties in achieving industrial decarbonization under the prevailing industrial policies; (ii) the emission reduction in steelmaking will play a key role, which can be achieved by the implementation of carbon capture and expansion of hydrogen technologies after 2040; (iii) even under mitigation scenarios, electrification and the use of biomass use in Japan’s industries will continue to be limited in 2050, suggesting a low possibility of large-scale fuel switching or end-use decarbonization. After stocktaking of the current industry-sector modeling in integrated assessment models, we found that such limited uptake of cleaner fuels in the results may be related to the limited interests of both participating models and industry stakeholders in Japan, specifically the interests on the technologies that are still at the early stage of development but with high reduction potential. It is crucial to upgrade research and development activities to enable future industry-sector mitigation as well as to improve modeling capabilities of energy end-use technologies in integrated assessment models.

    DOI

  • Revealing the impact of a projected emission trading scheme on the production technology upgrading in the cement industry in China: An LCA-RCOT model

    Yiyi Ju, Kiyoshi Fujikawa

    Resources, Conservation and Recycling: X   4  2019.12

    Authorship:Lead author, Corresponding author

     View Summary

    © 2019 The Author(s) The cement industry in China has been conducting overcapacity elimination through technology upgrading in the past years. Most of the overcapacity elimination policies are in the form of administrative and regulative approaches. However, the cost of overcapacity elimination by implementing command-and-control policies will be increasingly higher, at the same time, the orientation of such technology upgrading remains unknown. Such contradiction creates the necessities to reveal the impact of other policy instruments on the technology upgrading in the cement industry, as well as to clarify the optimal output allocation among all alternative technology choices. In this paper, an LCA-RCOT model (Life Cycle Assessment and Rectangular Choices Of Technologies) is established to provide such optimal technology combination with the constraints from a projected emission trading scheme (ETS). The results show that under an ETS cap with a target of 5% reduction of emission, 10% of subsidy allowances, and one-way linking with another ETS with higher average market price, the optimal solution suggest that 114.5 billion USD of total output in the cement sector should be produced by small dry kilns, while 102.5 billion USD by large dry kilns. In all feasible solutions, the optimal technology combination may shift to fewer shaft kilns and more dry kilns. In the long run, the climate policy instrument, ETS, may promote the upgrading of production technology by decomposing the total emission mitigation costs to the factor inputs of each cement producer.

    DOI

  • Long-term estimation of plastic material resources from end-of-life vehicles in China: a scenario analysis considering multiple industry standards

    Caimin Wu, Yang Li, Yifeng Zhang, Yanhui Liu, Shiyu Huang, Yiyi Ju

    Journal of Material Cycles and Waste Management    2022.03  [Refereed]

    Authorship:Corresponding author

    DOI

  • Estimation of end-of-life electric vehicle generation and analysis of the status and prospects of power battery recycling in China

    Yang Li, Yanhui Liu, Ying Chen, Shiyu Huang, Yiyi Ju

    Waste Management & Research: The Journal for a Sustainable Circular Economy   ( 0734242X2210800 )  2022.02  [Refereed]

    Authorship:Corresponding author

     View Summary

    With the development of the electric vehicle (EV), vehicle end-of-life (EOL) management has become a significant challenge. This study sets two EV sales scenarios (low and high), compares the impact of two battery replacement methods (buying a new vehicle or replacing the battery) on future EOL EV production, and predicts the difference in the amount of EOL EV battery production under two probability functions (normal and Weibull’s distributions). The results show that when the EV power battery is retired and the vehicle owner chooses to buy a new vehicle, the predicted scrap quantity under low sales and high sales (HS) scenarios in 2030 is 4.3 and 5.3 million, respectively. Replacing the battery and continuing to use the vehicle will mean fewer EOL vehicles are generated. Considering the construction of an EOL EV battery recycling management system in China is still in the exploratory period, it is necessary to encourage vehicle owners to replace the battery and continue to use the vehicle. Under a HS scenario, the predicted number of EOL EV batteries in 2030 is 3.8–7.4 million. In the next 10 years, the issue of EV recycling should be raised to the same level as the issue of EV popularisation.

    DOI

  • Recycling Potential of Plastic Resources from End-of-Life Passenger Vehicles in China

    Yang Li, Shiyu Huang, Yanhui Liu, Yiyi Ju

    International Journal of Environmental Research and Public Health   18 ( 19 ) 10285 - 10285  2021.09  [Refereed]

    Authorship:Corresponding author

     View Summary

    A rapid increase in the number of end-of-life (EoL) passenger vehicles has led to a large amount of waste plastics in China. However, the scale and efficiency of recycling resources from EoL vehicles still restricts the sustainable and healthy development of the automotive industry. The current behavior of automotive/recycling industry entities, as well as the strategy of waste management policymakers, may depend on the potential of total recyclable resources. To reveal such recycling potential of various plastic materials in EoL passenger vehicles, we predicted total EoL passenger vehicles in China from 2021 to 2030 (used the Weibull distribution) considering passenger vehicle ownership (estimated by the Gompertz model), quantified the demand for new passenger vehicles (estimated using its non-linear relationship with income level and passenger vehicle ownership), and assessed the recyclable plastics by categories and by provinces. The results show that (i) the annual average recycled plastic resources from EoL vehicles would exceed 2400 thousand t in 2030, more than 2.5 times in 2021, showing a great recycling potential; (ii) the differences among the three scenarios are relatively small, indicating that no matter the saturation level of passenger vehicles in China would be high or low, a rapid increase of recyclable plastic resources can be expected from 2021 to 2030; (iii) at the provincial level, a considerable gap between the potential of recycling plastic from EoL passenger vehicles and the regional processing capacity. Given such great potential and regional differences, the recycling policies should be applied in stages and consider the development level and recovery pressure in each region.

    DOI PubMed

  • Correction to: EMF 35 JMIP study for Japan’s long-term climate and energy policy: scenario designs and key findings (Sustainability Science, (2021), 16, 2, (355-374), 10.1007/s11625-021-00913-2)

    Masahiro Sugiyama, Shinichiro Fujimori, Kenichi Wada, Ken Oshiro, Etsushi Kato, Ryoichi Komiyama, Diego Silva Herran, Yuhji Matsuo, Hiroto Shiraki, Yiyi Ju

    Sustainability Science   16 ( 5 ) 1771  2021.09

     View Summary

    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

  • EMF 35 JMIP study for Japan’s long-term climate and energy policy: scenario designs and key findings

    Masahiro Sugiyama, Shinichiro Fujimori, Kenichi Wada, Ken Oshiro, Etsushi Kato, Ryoichi Komiyama, Diego Silva Herran, Yuhji Matsuo, Hiroto Shiraki, Yiyi Ju

    Sustainability Science   16 ( 2 ) 355 - 374  2021  [Refereed]

     View Summary

    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

  • アジアの脱炭素化のためのエネルギー・モデル連携に向けて

    杉山昌広, 居乂義, 滕飛, Yong-Gun Kim, 蘇斌

    環境経済・政策研究   13 ( 2 ) 85 - 88  2020.09

  • The potential and trend of end-of-life passenger vehicles recycling in China

    Yang Li, Kiyoshi Fujikawa, Junbo Wang, Xin Li, Yiyi Ju, Chenyi Chen

    Sustainability (Switzerland)   12 ( 4 ) 1 - 13  2020.02  [Refereed]

    Authorship:Corresponding author

     View Summary

    © 2020 by the author. The contradiction between limited resources and rapid development in the automobile industry has been driving society to seek the supply of recyclable resources from End-of-Life Vehicles (ELVs). It has become an urgent need for vehicle recycling policymakers to have an overall understanding of the end-of-life (EoL) vehicle population, as well as for vehicle producers to note what and how they can benefit from ELV recycling. This paper estimated the potential population of EoL passenger vehicles, all recyclable resources from them, as well as the economic values of these recyclable resources. The results show that in 2030, with a lighter-weight trend of passenger vehicles, more than 26.3 million passenger vehicles will be retired with 19.1 million tons of recyclable steel and 6.2 million tons of plastics. The theoretical economic value of all recyclable resources will reach 101.3 billion yuan ($14.4 billion) in 2030, which is an average of approximately 2.4 thousand yuan ($341.8) for each EoL passenger vehicle. It is time for the vehicle producers to shift to a manufacturing mode considering such large potential of ELV recycling. The scenario analysis suggests that in the context of a light-weighting trend, ELV resource recovery in the future calls for improvement in the recycling and reuse technologies of plastics and rubbers.

    DOI

  • Scenario analysis of the recycled copper supply in China considering the recycling efficiency rate and waste import regulations

    Junbo Wang, Yiyi Ju, Minxi Wang, Xin Li

    Resources, Conservation and Recycling   146   580 - 589  2019.07  [Refereed]

     View Summary

    © 2019 Elsevier B.V. The rapid economic growth and industrialization in China has induced a large copper demand since 1990, of which only approximately 40% is met by domestic ore deposits. However, a high dependence on imported copper ores, refined copper, or copper scrap can pose great risks to the sustainable copper resource supply and economic development of one country. An assessment of the in-use stock of refined copper is essential to estimate the potential supply of recycled copper, especially for countries with a high external dependence, such as China. A scenario analysis may further evaluate such a supply under different development pathways in the context of the increasingly strict import regulation of copper-containing end-of-use products. We introduced Material Flow Analysis and the Weibull lifetime distribution to estimate the in-use stock of refined copper from 1990 to 2035 in China based on the time-series data for sectoral refined copper consumption. The results show that the amount of generated copper scrap has been increasing from 1990 and reached 3.67 Tg in 2016, with 34.4% from the home appliances sector (mainly air-conditioning)and 26.6% from the power infrastructure sector. In 2035, the total would reach 17.7 Tg, with 42.8% from the power infrastructure sector and 19.7% from the home appliances sector. A scenario analysis was conducted considering different consumption growth rates, waste import regulation standards, and domestic recycling efficiency growth rates. The results show that under both scenarios, a total ban and limited imports of metal-containing scraps, the growth of the domestic recycling efficiency may improve the refined copper supply, which would be 0.867 Tg (67.4%)and 1.04 Tg (80.9%), respectively. With an adequate in-use stock of refined copper and an increasing recycling efficiency rate, domestic recycled secondary copper can cover the shrinking import source of copper scrap and become an essential source to meet the needs of the booming refined copper consumption in China.

    DOI

  • Modeling the cost transmission mechanism of the emission trading scheme in China

    Yiyi Ju, Kiyoshi Fujikawa

    Applied Energy   236   172 - 182  2019.02  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    © 2018 Elsevier Ltd The national emission trading scheme (ETS) in China, CHN-ETS, was established in 2017 following the start of its regional pilot markets in 2013. It will start with a coverage of electricity supply sector and eight pilot regions. Due to a highly regulated dispatch and pricing system in the electricity supply sector, the additional emission abatement costs brought by the ETS cannot be automatically conveyed between consumers and producers in all regions. This paper modeled the cost transmission of ETS in three scenarios based on the quantification results of regional and sectoral emission flows in the electricity supply sector under consumption-based accounting. The results show that the emissions transferred into pilot cities outweighed the emissions transferred out, not only through direct electricity uses but also through the indirect emissions embodied in other sectors that required intermediate inputs from electricity supply sectors in the pilot cities. Through the cost transmission mechanism, the additional abatement cost caused by the national ETS drove the increases in the household consumption of several energy-intensive sectors, including the metal mining sector in Hebei, the petroleum and gas sector in Heilongjiang, and the nonmetal mining sector in Sichuan, with a sensitive increase of 10.1%, 9.9%, and 3.5%, respectively. However, most sectors (745 of the 810) would suffer an increase rate below 0.1%. As long as the household welfare would be ensured, there is still room for the current average market price in the pilot cities to be further increased toward the official guidance price in the nation-wide market.

    DOI

  • Revealing the bilateral dependencies and policy implication of food production of Japan and China: From the perspective of Food-Energy-Water nexus

    Yiyi Ju

    Ecological Modelling   391   29 - 39  2019.01  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    © 2018 Elsevier B.V. The world food price crisis in 2007/08 has aroused worldwide attention to the global food price volatility and food self-sufficiency issues. This paper modelled the entire environment of food production and transaction from a holistic view by a Food-Energy-Water (FEW) nexus in order to reveal the hidden connections related to the food self-sufficiency issue, including the interdependencies of food production with its restraining factors (hybrid energy, hybrid water), other production sectors, and international exchanges. This paper mapped all direct and indirect flows in the FEW nexus and projected a potential Emission Trading Scheme (ETS) to figure out the impacts of policies on FEW nexus flows, nexus robustness, total input of all sectors, and household expenditures in Japan and China. The results show that the pattern of food-related extraction flows was more imbalanced than the pattern of hybrid energy flows, due to the high dependence of Japan on the food supply of China (16.11% of total food-related extractions). An ETS may increase Japan's total household expenditure on imported goods from China in the fields of sugar refining (1.3096%), processing vegetable oils and fats (0.1164%), processing of meat cattle (0.1010%), as well as slightly decrease the system robustness of the total nexus.

    DOI

  • City-level features of energy footprints and carbon dioxide emissions in Sichuan province of China

    Junbo Wang, Liu Chen, Lu Chen, Xiaohui Zhao, Minxi Wang, Yiyi Ju, Li Xin

    Energies   12 ( 10 )  2019  [Refereed]

    Authorship:Corresponding author

     View Summary

    © 2019 by the authors. Licensee MDPI, Basel, Switzerland. The sustainable development of the western region of China has always been essential to the national development strategy. The Western region has undertaken an industrial transfer from the Eastern and Central regions. Therefore, the CO2 emission intensity in the western region is higher than those of the Eastern and Central regions of China, and consequently its low-carbon development pathway has an important impact for China as a whole. Sichuan Province is not only the province with the highest CO2 emissions, but also the most economically developed province in Western China in 2018. In order to promote low carbon development in the western region, it is important to understand the features of emissions in Sichuan Province and to formulate effective energy strategies accordingly. This paper uses the IPCC regional emission accounting method to calculate the carbon emissions of 15 cities in Sichuan province, and to comply with the city-level emission accounts. The results show that the total carbon emissions of Sichuan province over the past 10 years was 3258.32 mt and reached a peak in 2012. The smelting and pressing of ferrous metals, coal mining and dressing were the leading sectors that contributed to the emissions, accounting for 17.86% and 15.82%, respectively. Raw coal, cleaned coal, and coke were the most significant contributors to CO2 emissions, accounting for 43.73%, 9.55%, and 6.60%, respectively. Following the above results, the Sichuan provincial government can formulate differentiated energy structure policies according to different energy consumption structures and carbon emission levels in the 15 cities. By controlling the level of total emissions and regulating larger industrial emitters in Sichuan province, some useful information could be provided as an essential reference for low-carbon development in Western China, and contribute to the promotion of emissions mitigation from a more holistic perspective.

    DOI

  • Tracking the PM2.5 inventories embodied in the trade among China, Japan and Korea

    Yiyi Ju

    Journal of Economic Structures   6 ( 1 ) 1 - 16  2016  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    © The Author(s) 2017. Due to its long-term negative health effects and increasing emissions, the PM2.5 issue has caused rising concerns in recent years. Although official media from East Asian countries tend to avoid blaming PM emission sources on their neighboring countries, researches have proved the existence of pronounced long-range trans-boundary particulate matters transported by nature force and by human activities. In this con-text, this paper included the structural path analysis (SPA) to quantify trans-boundary PM2.5 at sector level, track its transaction paths and figure out the linkages between consumption and production responsibilities of China, Japan and Korea. Based on the results and policy reviews of current environmental cooperation mechanisms, this paper found that: Considering the China–Japan and China–Korea trades, China’s net exportation of embodied PM2.5 emissions has exceeded the importation rates over 10 times (CHN → JPN, 56.53 kt, JPN → CHN, 3.58 kt; CHN → KOR, 59.19 kt, KOR → CHN, 5.31 kt). Japan and Korea benefited from importing raw materials with high emission intensity from China to meet domestic consumption needs and keep a low national emission level. China, the largest emitter in the world, should first take the responsibility to mitigate its huge domestic PM2.5 emission. However, the relocated emissions from its neighboring countries should not be ignored. For Japan or Korea, due to the close economic interdependence and geographical position, any contribution to the reduction of the trans-boundary emissions or to the solution of atmosphere problems within China also helps those countries themselves. In the long run, all three countries would benefit from enhancing subregional environmental cooperation.

    DOI

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Books and Other Publications

  • China’s Carbon-Energy Policy and Asia’s Energy Transition Carbon Leakage, Relocation and Halos

    Edited By Akihisa Mori( Part: Joint author, Chapter 11., Generating or receiving carbon leakages?: An examination of China in Asia Le Tuyet Vo and Yiyi Ju)

    Routledge  2021.12

Misc

Research Projects

  • 石炭投融資撤退による環境・経済・経営持続性への移行:アジアの事例分析

    日本学術振興会  科学研究費助成事業 基盤研究(A)

    Project Year :

    2021.04
    -
    2025.03
     

    森 晶寿

  • Industrial Decarbonization Towards National Carbon Neutrality: Optimal Technology Combination and International Technology Comparison in The Cement Industry

    日本学術振興会  科学研究費助成事業 若手研究

    Project Year :

    2022.04
    -
    2025.03
     

    居 乂義

Presentations

▼display all

Specific Research

  • Perceived Feasibility of Japan’s Mitigation Scenarios: Expert Perspectives

    2021   Masahiro Sugiyama, Hiroto Shiraki

     View Summary

    From June 2020 to March 2022, we have conducted a semi-structured interviewsurvey to collect the perspective of over 110 experts on the feasibility anddesirability of carbon neutrality in Japan. Through the survey, we explored the following research questions: i) How do experts perceive the feasibility and desirability ofdecarbonization transition? Any differences among expert groups from differentdisciplines? What is the agreement level?ii) What are the barriers to decarbonization transition in Japan? How doexperts assess each of them? Which barriers present the greatest risk to thedecarbonization transition? The results show that experts think of feasibility as continuous, notbinary. Collectively, the response suggests that achieving net-zero emissionsby 2050 is more infeasible than feasible. The assessment also contributes to abetter understanding of the most important barriers to decarbonizationtransition in Japan, as well as the multi-dimensional feasibility ofcarbon neutrality. Along with the interviews, we have presented our preliminaryresults in academic conferences (SEEPS 2021, IAMC 2021) and workshops (WIAS/RIEEMinternal seminars) and collected comments to improve our work.

 

Syllabus

Teaching Experience

  • Introduction to Econometrics

    Waseda University, Graduate School of Asia Pacific Studies  

    2022.04
    -
    Now
     

  • Introduction to Social Researches

    Waseda University, School of Social Sciences  

    2021.10
    -
    2022.02