Japan activated 40,000 tonnes per year of waste-plastics chemical recycling capacity across March and April, commissioning two 20,000-tonne facilities within five weeks as Middle East naphtha-supply concerns push circular feedstocks into the planning cycles of major petrochemical operators.

Mitsubishi Chemical and ENEOS brought their joint supercritical-water unit at Mitsubishi's Ibaraki Plant online in March, three months after completing construction last July. The unit uses high-temperature, high-pressure water licensed from Britain's Mura Technology to break polyolefins down into a synthetic crude oil and a naphtha fraction.

What does supercritical water change?

Conventional pyrolysis applies heat externally, creating localised hot spots that carbonise the feedstock. Supercritical water distributes heat through the polymer mass, which the head of Mitsubishi Chemical's CN and CE Business Group linked to higher oil yields. ENEOS refines the synthetic crude into transportation fuels; Mitsubishi Chemical routes the naphtha fraction back into basic-chemicals manufacturing.

A second 20,000-tonne plant entered service in April at Idemitsu Kosan's Chiba complex. Idemitsu uses catalysts originally developed for oil refining, materials the company now repurposes after they exhaust their refining lifespan. The approach targets a higher naphtha yield in the output slate.

How far from naphtha parity?

Unit economics remain the chief obstacle. Chemical recycling currently runs two to three times the cost of naphtha produced directly from crude oil. Both operators treat capacity expansion as the primary cost lever.

Targets on the board:

• Mitsubishi Chemical plans to lift annual recycled-plastic throughput past 100,000 tonnes in the 2030s
• Idemitsu is evaluating additional units at its Chiba site and at refineries in Aichi and Hokkaido
• Nobuhiro Miyagishi, executive officer and general manager of Idemitsu's Basic Chemicals Department, said the company is exploring co-location with municipal waste-treatment plants

Feedstock coverage sits behind a second hurdle. The Ibaraki unit handles soft polyolefins — polypropylene and polyethylene. The Chiba plant accepts the same pair plus polystyrene. Both operators are developing rigid-plastic lines.

What does this shift against the naphtha benchmark?

Japan sources more than 90% of its oil imports from the Middle East, a concentration that leaves petrochemical and refining customers exposed to any disruption in seaborne crude flows. The Plastic Waste Management Institute counted 9.11 million tonnes of waste-plastic generation in 2024, of which only about 20% moved through material recycling and close to 70% through incineration with energy recovery.

Chemical recycling sidesteps the mechanical degradation that limits closed-loop material recycling. Against incineration, the process cuts emissions by roughly 40% by keeping carbon in a hydrocarbon output rather than releasing it as CO₂.

Downstream offtake is already forming. Mitsubishi Chemical is taking chemically recycled resins back into consumer packaging with Kewpie and Albion. Idemitsu is processing construction scrap with Takenaka Corporation.

What's the next milestone?

The decisive milestone for both operators is a unit-cost curve that closes the two-to-three-times gap with virgin naphtha by the time the additional 80,000 tonnes of Mitsubishi capacity is scheduled to come online in the 2030s. Government subsidy frameworks under Japan's plastic-resource circulation strategy will determine whether that cost trajectory bends fast enough for circular feedstock to displace Middle East barrels at scale.