(2023/09/19)

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Investigating the role of greener plastics for Japan’s carbon neutral goals
Japan’s plastic problem is a huge barrier to carbon neutrality. Could bioplastics and recycledplastics be the answer?
Fukuoka, Japan – Japan has a plastic problem. Thanks in part to an overabundance ofpackaging, the country is the second largest producer of plastic waste per capita.
While plastic pollution is a well-known cause for concern, an often-overlooked issue is how
plastics contribute to global warming. Plastics are a surprisingly large cause of carbon
emissions, with roughly 4.5% of global emissions caused by the plastics sector.
Now, joint research between Kyushu University and Yokohama-based start-up company, SotasCo., Ltd, has investigated the potential for Japan’s market to incorporate a greener plastic
supply chain.
“The Japanese government has pledged to achieve carbon neutrality by 2050. However, thepredominant method that Japan uses to get rid of plastic waste is ‘thermal recycling’ orincineration, which releases carbon dioxide into the atmosphere,” says senior author Professor
Andrew Chapman, from Kyushu University’s International Institute for Carbon Neutral Energyand Research. “We have examined whether switching to more sustainable recycled plastics
and bioplastics is a competitive and effective alternative to current carbon reduction policies.”
The researchers began with an economic and environmental assessment of six commonlyused plastic types, based on whether they were made using virgin, recycled or bioplastic.
They scored the plastics using four different criteria: global warming potential, cost,
recyclability and perceived quality for manufacturers. Depending on the weighting given toeach factor, the researchers calculated how desirable each plastic was under a number ofscenarios.
In general, the researchers found that virgin plastics, which are made directly from fossil
fuels, are perceived to be the highest quality, but have a high global warming potential andare relatively expensive.
Recycled plastics, on the other hand, are cheaper and also have a lower global warming
potential. However, plastics with a higher blend of recycled material were perceived to be oflower quality and recyclability also varied greatly for each plastic type.
“One issue is that it can be physically harder to separate out some types of plastics before
recycling and additionally, some plastics can only be recycled a certain number of times,” says
first author Yuuki Yoshimoto, President of Sotas Co., Ltd. “It’s therefore important to establish
a robust, centralized chain of custody to keep track of how many times a piece of plastic has
been recycled to provide quality assurance to end users.”
The analysis also revealed that bioplastics, which are made from plants, have the lowest
global warming potential. Some bioplastics can even be carbon-negative, as the plants take incarbon dioxide from the atmosphere as they grow, which is then sequestered in the material.
However, bioplastics are much more costly to make than virgin or recycled plastics, and, as
drop-in replacements are not always available, currently perform less well regarding
perceived quality. Additionally, starch-based bioplastics require arable land to grow the crops.
“Food versus plastic production is not a fight we want, as land resources are very limited inJapan,” says Prof Chapman. Instead, the researchers suggested further funding for research
into cellulose-based bioplastics, which can be sourced from wood pulp.
One additional factor that could help bridge the gap in the cost between bioplastics and virginplastics is the consumers’ willingness to pay. Prior research suggests that consumers arewilling to pay more for environmentally-friendly products, which the researchers plan toinvestigate in detail and incorporate into their analysis.
“This is a complex situation, with no one-size-fits-all solution,” concludes Yoshimoto.
“Ultimately we hope this analysis can help policymakers decide what recycling processes tosupport, and to inform manufacturers which plastics can best meet their manufacturing andcarbon reduction goals.”This research also considers the economic efficiency of carbon reduction via plastic recycling
and bioplastic replacement, broadening the potential policy approaches which can be pursued
by policymakers.
###For more information about this research, see "Toward Economically Efficient Carbon
Reduction: Contrasting Greening Plastic Supply Chains with Alternative Energy
Policy Approaches" Yuuki Yoshimoto, Koki Kishimoto, Kanchan Kumar Sen, Takako Mochida,
Andrew Chapman, Sustainability, https://doi.org/10.3390/su151713229

Fig. 1. Multicriteria assessment of virgin,
recycled and bioplastics for six different plastictypes considering cost, emissions, perceived
quality, and recyclability. The higher thepoints, the greater the desirability of theplastic to manufacturers.

Fig. 2. Yuuki Yoshimoto, Representative Director andPresident of Sotas Co., Ltd. (left) and Professor Andrew
Chapman (right) performing joint research in Kawasaki City.

[Contact]
Andrew John Chapman, Associate Professor
International Institute for Carbon-Neutral Energy Research
Tel: +81-92-802-6878
E-mail: chapman@i2cner.kyushu-u.ac.jp