Miura Minori A research group consisting of Associate Professor Andrew Chapman and Professor Shuntaro Tsubaki of I2CNER, together with Professor Satoshi Fujii of the National Institute of Technology, Okinawa College, conducted a study focusing on Okinawa Prefecture to evaluate the potential of a technology that converts plastic waste into hydrogen through microwave-assisted pyrolysis.
In this study, we combined a resident survey, interviews with relevant organizations, and laboratory-scale catalytic pyrolysis experiments to examine the extent to which technology for producing hydrogen from plastic can address waste management and energy system challenges in regions surrounded by the sea. Okinawa faces challenges such as limited final disposal site capacity, the cost of transporting waste outside the prefecture, and a lack of large-scale plastic recycling infrastructure. At the same time, interest in hydrogen utilization is growing as the region works toward decarbonization. A survey of 91 residents in Okinawa Prefecture revealed strong support for improving the plastic recycling system, but also identified factors hindering participation. Many respondents had limited knowledge about the types of recyclable plastics and the facilities available, and cited the time-consuming nature of sorting and cleaning as major barriers. Furthermore, the results showed that willingness to pay for recycling services is conditional, with cost being the primary concern. On the technical front, the research group demonstrated that, under controlled experimental conditions, polypropylene can be converted into a gas rich in hydrogen through microwave-assisted catalytic pyrolysis. The addition of activated carbon enabled the heating of plastics that typically do not absorb microwaves, while iron-based catalysts promoted hydrogen production. In particular, iron-based catalysts containing multiple elements demonstrated the ability to increase hydrogen production while suppressing carbon dioxide production. However, this study also reveals a significant socio-technical mismatch. The process that demonstrated high performance in experiments requires clean and relatively homogeneous plastic feedstock. On the other hand, it was confirmed that actual household plastic waste often consists of a mixture of multiple types of resins and frequently contains food residues, labels, and dirt, placing a significant burden on residents in terms of sorting and cleaning. Therefore, it is considered appropriate to position the conversion of plastic to hydrogen, at this stage, not as a standalone circular solution for mixed household plastic waste, but rather as a limited energy recovery technology targeting pre-sorted industrial and commercial plastics. If this technology can be linked to local hydrogen demand—such as hydrogen co-firing in gas turbines for power generation or industrial applications—it has the potential to contribute to regional decarbonization while reducing the burden on existing waste management systems.
Translated with DeepL.com (free version)
The results of this study were published in Environmental Challenges on June 11, 2026 (local time).
The full press release (Japanese) is available as a PDF here.
【Paper Information】
Journal：Environmental Challenges
Title：Plastic-to-Hydrogen Conversion in Island Contexts: A Socio-Technical Assessment of Microwave Pyrolysis in Okinawa
Authors：Andrew Chapman, Shuntaro Tsubaki, Rie Honda, Ibrahim Maamoun, and Satoshi Fujii
DOI：10.1016/j.envc.2026.101544
English 
Japanese