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In cities, a variety of human activities are densely concentrated. Conventional environmental pollution problems have focused on the impact of urban activities on the health and living environment of the people who live there. Today, however, a broader perspective is needed to reconstruct cities from an environmental perspective that also considers the global environment and sustainability for future generations.

Against this background, there is a need to draw up a mechanism for efficient use of materials and energy in cities, as well as to establish a system of circulation and symbiosis in cities and regions, such as utilizing single-use products consumed in cities and durable consumer goods and buildings accumulated in cities as recyclable resources.

In order to scientifically contribute to these social demands, Regional Circulating and Ecological Laboratory approaches a wide range of issues, from social system issues such as plastic resource circulation, to structural analysis of the generation of environmental burdens throughout production and consumption at the national level, to the development of methodologies to chart future urban goals and pathways to achieve them in line with the SDGs (Sustainable Development Goals).

Specific areas of research include the following:

1. Future scenarios for decarbonized regions

We are conducting research to plan future goals for cities and leading projects to get there, using evaluation indicators that cover environmental, economic, and social fields for 2030 as defined by the United Nations, models for calculating the environmental and economic effects of resource recycling and regional energy technologies, and a regional integrated assessment model to calculate appropriate goals for the future.

We aim to develop a process to select evaluation indicators for cities using the SDGs and other indicators to quantitatively evaluate the environmental, economic, and social characteristics of a region and plan measures for local energy, resource circulation, local transportation, environmental improvement, etc., taking advantage of the "individuality" of that municipality, as well as to quantitatively evaluate the effectiveness of these measures.

Related literature

  • Dou, Y., Fujii, M., Fujita, T., Gomi, K., Maki, S., and Tanikawa, H.: “Potential of waste heat exchange considering industrial location changes: a case of Shinchi-Soma Region in Fukushima, Japan,” Journal of Environmental Systems Research 73(6), pp. II_353–II_363, https://doi.org/10.2208/jscejer.73.II_353 (2017)
  • Gomi, K., Ashina, S., Fujita, T., and Masui, T.: “Development of a methodology for regional future scenarios considering interaction of industry and population and application in So-ma Region in Fukushima prefecture,” Journal of Environmental Systems Research 71(6), pp. II_151–II_162, https://doi.org/10.2208/jscejer.71.II_151 (2015)

2. Regional circular and ecological economy where decarbonization and circular economy are realized

The regional circular and ecological economy, in which each region forms a self-reliant and decentralized society, complementing and supporting each other with local resources, among others, is expected to be a key to achieve social transformation, including the realization of a decarbonized society, and to serve as a leading example for Japan to disseminate the SDGs. The regional circular and ecological economy is proposed in the Fifth Basic Environment Plan decided by the Cabinet in 2018, and requires the realization of a mechanism to enhance the value of regions through projects that utilize diverse environmental, social, and economic resources by taking advantage of regional characteristics, and spill over from there to regional values in the environmental, economic, and social fields.

Toward the formation of the regional circular and ecological economy, we are quantitatively clarifying measures such as resource circulation between cities and industrial facilities, and hierarchical use of renewable energy and waste heat, among others.

Related literature

  • Gomi, K., Fujita, T., Ochi, Y., Ogawa, Y., Oba, M, and Togawa, T.: “Proposal of analytical framework for research of regional circular and ecological sphere,” Journal of Environmental Systems Research 76(6), pp. II_249–II_260, https://doi.org/10.2208/jscejer.76.6_II_249 (2020)
  • Geng, Y., Fujita, T., Park, H., Chiu, A. S. F., and Huisingh, D.: “Recent progress on innovative eco-industrial development,” Journal of Cleaner Production 114, pp. 1–10, https://doi.org/10.1016/j.jclepro.2015.09.051 (2016)
  • Geng, Y., Fujita, T., and Chen, X.: “Evaluation of innovative municipal solid waste management through urban symbiosis: a case study of Kawasaki,” Journal of Cleaner Production 18, pp. 993–1000, https://doi.org/10.1016/j.jclepro.2010.03.003 (2010)
  • Berkel, R. V., Fujita, T., Hashimoto, S., and Fujii, M.: “Quantitative assessment of urban and industrial symbiosis in Kawasaki, Japan,” Environmental Science & Technology 43(5), pp. 1271–1281, https://doi.org/10.1021/es803319r (2009)

3. Systems analysis of resource circulation

Against a backdrop of international movements towards the plastic-free and decarbonized society, measures for reduction in plastic use and resource circulation including recycling of plastics are also domestically promoted in Japan. Resource circulation is expected to play a role of sustainable raw material supply as the arterial industry, as well as a role of the proper waste treatment as the venous industry. For plastics and other various materials, it is required to show the image of sustainable resource circulation that is consistent with the target of decarbonization, while satisfying the above roles.

Taking plastics as a main subject, we are studying on the grand design of resource circulation through interindustry symbiosis, which takes a panoramic view of related industries such as the petrochemical and steel industries, by making full use of system analysis methods including material flow analysis (MFA) and life cycle assessment (LCA).

Related literature

  • Olalo, K. F., Nakatani, J., and Fujita, T.: “Optimal process network for integrated solid waste management in Davao City, Philippines,” Sustainability 14 (4), p. 2419, https://doi.org/10.3390/su14042419 (2022)
  • Kawai, M., Nakatani, J., Kurisu, K., and Moriguchi, Y.: “Quantity- and quality-oriented scenario optimizations for the material recycling of plastic packaging in Japan,” Resources, Conservation and Recycling 180, p. 106162, https://doi.org/10.1016/j.resconrec.2022.106162 (2022)
  • Nakatani, J., Maruyama, T., and Moriguchi, Y.: “Revealing the intersectoral material flow of plastic containers and packaging in Japan,” Proceedings of the National Academy of Sciences 117(33), pp. 19844–19853, https://doi.org/10.1073/pnas.2001379117 (2020) (Press Release)
  • Nakatani, J., Konno, K., and Moriguchi, Y.: “Variability-based optimal design for robust plastic recycling systems,” Resources, Conservation and Recycling 116, pp. 53–60, https://doi.org/10.1016/j.resconrec.2016.09.020 (2017)
  • Nakatani, J.: “Life-cycle inventory analysis of recycling: Mathematical and graphical frameworks,” Sustainability 6 (9), pp. 6158–6169, https://doi.org/10.3390/su6096158 (2014)

4. Footprint analysis of urban activities

Urban activities are founded on various goods from single-use and durable products to buildings. Recently, a lot of attention is paid to footprint analysis that evaluates potential environmental impacts and resource consumption along supply chains. Their hotspots, on which improvement efforts should be focused, need to be identified for enhancing the sustainability of urban activities.

We are analyzing supply chains of various goods and services to reveal the hidden environmental impacts and resource consumption of urban activities, by applying data and methods of life cycle assessment (LCA) and environmental input–output analysis (EIOA).

Related literature

  • Nakatani, J., Tahara, K., Nakajima, K., Daigo, I., Kurishima, H., Kudoh, Y., Matsubae, K., Fukushima, Y., Ihara, T., Kikuchi, Y., Nishijima, A., and Moriguchi, Y.: “A graph theory-based methodology for vulnerability assessment of supply chains using the life cycle inventory database,” Omega 75, pp. 165–181, https://doi.org/10.1016/j.omega.2017.03.003 (2018)
  • Nakamura, S., Iida, A., Nakatani, J., Shimizu, T., Ono, Y., Watanabe, S., Noda, K., and Kitalong, C.: “Global land use of diets in a small island community: A case study of Palau in the Pacific,” Environmental Research Letters 16 (6), p. 065016, https://doi.org/10.1088/1748-9326/ac0212 (2021)
  • Zhang, Q., Nakatani, J., Shan, Y., and Moriguchi, Y.: “Inter-regional spillover of China’s sulfur dioxide (SO2) pollution across the supply chains,” Journal of Cleaner Production 207, pp. 418–431, https://doi.org/10.1016/j.jclepro.2018.09.259 (2019)
  • Nakatani, J., Maruyama, T., Fukuchi, K., and Moriguchi, Y.: “A practical approach to screening potential environmental hotspots of different impact categories in supply chains,” Sustainability 7 (9), pp. 11878–11892, https://doi.org/10.3390/su70911878 (2015)
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