日本の脱炭素化技術のためのカスケード型電池利用システム
（令和 6年度）
A cascaded battery use system for decarbonization technologies in Japan

研究概要

Japan has set a carbon-neutral society goal by 2050. Transport electrification and renewable energy are essential to decarbonization. Yet, the supply risk of critical battery materials and the variable nature of solar and wind power present significant challenges to decarbonization efforts. Retired traction batteries (RTBs) from electric vehicles (EVs), typically retaining 70-80% of their original capacity, can be reused as energy storage batteries (ESBs) to stabilize and shift solar and wind power generation until their capacity drops to 30-40%. Since the waste management hierarchy of reuse is higher than recycling, the reuse of RTBs as ESBs not only optimizes battery capacity efficiency but also reduces waste treatment pressure; it also transforms the competitive relationship between EVs and solar and wind power into a symbiotic one, mitigating resource supply pressure. Pioneers like Nissan and Sumitomo have technologically demonstrated the cascaded use of batteries for EVs and renewable energy storage recently. As the outbreak period of RTBs and ESBs gradually arrives, this study aims to 1) determine the matching degree between RTBs and ESBs and 2) clarify the resource conservation and carbon reduction potential of the battery cascade system, thereby providing data and management recommendations to assist Japan in building an efficient battery use system during the decarbonization transition.

研究の性格

• 主たるもの：応用科学研究
• 従たるもの：政策研究

全体計画

1.1 data collection & survey (2024/05-08), 1.2 estimation (2024/08-10); 2.1 data curation (2024/10), 2.2 analysis (2024/10-12); 3.1 data collection (2024/12-2025/01), 3.2 analysis (2025/01-03), 3.3 article writing (2025/03-05)

今年度の研究概要

1. Estimating RTB generation and ESB demands in Japan by 2050
Our initial step is to conduct a literature review to collect nationwide and regional data of Japan on 1) historical EV sales and solar and wind power deployment, 2) future increase goals for EVs and solar and wind power toward carbon neutrality, and 3) Statistical or experimental lifespans of EVs, traction batteries, photovoltaic panels, wind turbines, and ESBs. We also plan to engage with Nissan and Sumitomo for an on-site survey of their RTB reuse demonstration facilities (e.g., Namie EV battery station), aiming to obtain information on the battery capacity adapted per unit solar and wind power installation and the secondary lifespan of RTBs in power storage systems. Integrating these datasets into a dynamic urban metabolism model and using the Weibull distribution for survival rate assessment, we aim to estimate the demand, stock, and end-of-life generation of traction batteries and ESBs.
2. Determining national and regional matching degrees and solutions between RTBs and ESBs
We plan to conduct a heat map analysis to determine the matching degrees of RTBs and ESBs regionally. We also plan to perform an optimal path analysis to identify optimal transfer routes, required remanufacturing capability and distribution, and required recycling capability and distribution for the battery cascade system across Japan.
3. Clarifying resource conservation and carbon reduction potential of a battery cascade system
We plan to conduct a literature review to collect data on 1) Li-ion battery material compositions and 2) carbon emission factors of their manufacturing and remanufacturing. We aim to set up a battery cascade scenario and a baseline scenario to calculate the total material consumption of EVs and solar and wind power as a whole under different scenarios; combining carbon emission factors, we also strive to evaluate the carbon emission for each scenario. Finally, a scenario comparison can clarify the resource conservation and carbon reduction potential of a battery cascade system.