Japan's fully circular economy: A future envisioned by urban mining resources such as smartphones and solar sharing on farmland
Updated by Hiroshi Komiyama on December 12, 2025, 5:21 PM JST
Hiroshi KOMIYAMA
（Platinum Initiative Network, Inc.
After serving as Professor at the University of Tokyo, Dean of the Graduate School of Engineering and Dean of the Faculty of Engineering, and President of the University of Tokyo (28th), he was appointed Chairman of the Mitsubishi Research Institute in 2009, and Chairman of the Platinum Initiative Network in 2010 (to be incorporated as a general incorporated association in 2022). Other positions include President of the STS Forum, Chairman of the Association for Super-Education, Chairman of the United Nations University Cooperation Foundation, Chairman of the International Science and Technology Foundation, and Chairman of the Heat Pump and Thermal Storage Center Foundation. He also received the Dubai Knowledge Award (2017), the Order of the Star of Solidarity of Italy (2007.) and "Information and Communication Month" Commendation from the Minister of Internal Affairs and Communications (2014), the Zaikai Award Special Prize (2016), and the Commendation for Merit in Promoting a Maritime Nation (2016), among many other national and international awards.
Japan, a "pioneer nation" where challenges like declining birthrates, aging populations, and resource/energy issues have emerged ahead of other countries, has the opportunity to create a global role model by solving these problems. The "Platinum Society" we should aim for is one that achieves harmony and coexistence with the environment and a vibrant society. Essential to this is a "fully circular economy" that liberates humanity from the depletion of energy and resources.Japan possesses the technological capabilities and proven track record to pioneer this new economic model for the world.
Japan possesses advanced technological capabilities to consistently produce goods from raw material development to final products, building a social system that boasts high energy efficiency and resource utilization efficiency. For resource-scarce Japan, increasing the self-sufficiency rate of mineral resources through recycling represents the optimal approach and could serve as a model for humanity to strive toward.
Achieving recycling requires three key elements: a social system for resource recovery, product design that facilitates resource separation, and separation technology.
Cities accumulate vast resources. Within these "urban mines," electronic devices in particular can be considered high-grade "ore."
For example, medals for the Tokyo 2020 Olympic and Paralympic Games were made from smartphones and other devices provided by citizens. This exemplifies the value of urban mining. Collecting one ton of smartphones yields approximately 150 grams of gold—equivalent to about 30 times the amount found in an average gold mine. Similarly, the silver and copper content is of higher grade than that found in natural mines.
To efficiently recover urban resources, I propose building a "digital twin of urban mines." This system would map all infrastructure in Japanese cities—where iron, rare earths, and glass are located—as data. By linking it with building BIM/CIM data and installation records from equipment manufacturers like air conditioners, we can data-driven identify vast "resource" locations and enable efficient recovery.
In the industrial sector, reducing energy consumption during manufacturing is crucial.
In the steel industry, electric arc furnaces that melt scrap and recycle it into steel products are gaining attention.Compared to blast furnaces that use iron ore, electric furnaces can reduce energy consumption to about one-fifth. The news that electric furnace manufacturer Tokyo Steel has begun producing lightweight, high-strength high-tensile steel (HTS) for automobiles—which has extremely stringent quality requirements—from scrap, and has signed a contract for Toyota Motor Corporation to purchase it, is a major trend signaling the shift towards a circular economy.
In the automotive industry, where energy savings throughout the entire lifecycle are essential, adopting electric furnace steel—which significantly reduces energy consumption during manufacturing—is crucial from an environmental impact reduction perspective.
Furthermore, in the construction sector, Taisei Corporation and Nippon Express are collaborating on an initiative to efficiently collect and recycle scrap materials (construction by-products) generated at new construction sites.Nippon Express, responsible for logistics, has established a system to efficiently collect and sort these scraps—previously disposed of inefficiently as waste—group them by material type, and transport them to recycling plants. This achieves improved transport efficiency and CO2 reduction. There are also signs that this initiative is beginning to spread among general contractors.
Utilizing farmland is essential for decarbonizing the energy that supports material cycles in Japan.
Japan has approximately 4.2 million hectares of cultivated land, about 420,000 hectares of abandoned farmland, and roughly 700,000 hectares of pasture. Harnessing the potential of this vast land—totaling about 5.3 million hectares—is the goal of solar sharing (agricultural solar power generation).
Chiba Eco Energy and Tsunagu Farm, a venture originating from Chiba University, has been promoting the "Oki-do Model for Fostering Well-being" centered on solar sharing in the Oki-do area of Midori Ward, Chiba City. They received the Grand Prize and the Individual Theme Award ("Coexistence with Population Decline") at the 13th Platinum Awards.
This Ōkido model enhances regional sustainability by combining agriculture with power generation. A one-hectare demonstration project yielded remarkable results: maintaining annual vegetable sales of approximately ¥3 million while generating annual power revenue of about ¥20 million, resulting in total income eight times higher. The initial investment (¥100 million) can be recouped within five years, achieving both agricultural and energy self-sufficiency while contributing to decarbonization.Estimates suggest that if solar sharing were implemented across Japan's total farmland (approximately 5.3 million hectares) with a 30% solar panel coverage rate, it could generate five times the current total electricity output. This demonstrates that promoting renewable energy is key to regional revitalization.
Achieving a fully circular economy depends not only on technological efforts but also significantly on cultural foundations and the "design philosophy" of products. In Japan, a "culture of waste aversion" has been deeply rooted since ancient times, and the social system of separate waste collection functions relatively smoothly. The high level of public support among the Japanese people provides a strong foundation for advancing solutions to this societal challenge.
Particularly important is "product design that facilitates resource separation," one of the key elements of recycling. ASICS has developed running shoes that are easy to disassemble. This is an example of a design that incorporates structural innovations to make recycling easier and allows for simple disassembly.
Additionally, Shin-Etsu Chemical, a chemical manufacturer, contributes to energy savings by supplying high-purity rubber raw materials that minimize the presence of unreacted monomers to the utmost extent. This eliminates the need for users to perform heat treatment (an energy-consuming process) during secondary processing.
Product design requires management throughout the entire lifecycle, considering not only use but also disposal and recycling. For example, designs like the motors used in hybrid vehicles—which remain robust during use yet allow components to be easily separated during disassembly and recovery—are essential for achieving a fully circular society.
The fully circular economy we aim to achieve will be realized when the three elements of "technology," "institutions," and "culture" come together. In terms of "technology" and "culture," Japan already possesses the foundation to become a global leader.
The remaining challenges are "institutional frameworks" and "economic viability." While institutional constraints exist—such as legal barriers to regional waste management—these walls crumble instantly when the circular economy becomes profitable, that is, when its economic benefits become clear. Politicians and administrators then spring into action, accelerating the system. (Hiroshi Komiyama, Chairman of the Platinum Concept Network and Honorary Editor-in-Chief of Forest Circular Economy)
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