Pyrolysis recycling technology: Promises and challenges in 2024

As the pressure to transition from a linear to a circular economy mounts, companies are increasingly rethinking the entire lifecycle of their products. This shift involves adopting practices that emphasise reuse, recycling and sustainable resource management.

Regrettably, the recycling rate for plastics is abysmally low, at just 9%. The remainder ends up in landfills, incineration facilities, or as environmental pollution—with far-reaching impacts on the environment, wildlife, human health and the economy. A major limitation of traditional mechanical recycling is its inability to effectively manage the variety of mixed plastic waste streams in use today, as well as inefficiencies in controlling contamination from various plastic sources.

Advanced recycling comprises a set of innovative technologies that surpass mechanical recycling. While mechanical recycling involves sorting, cleaning and melting plastics to create new items; advanced recycling deconstructs plastics at a molecular level, converting them into raw materials for reuse.  This technique can manage a broader range of plastic types. 

Pyrolysis is one of the more established forms of advanced recycling, and it appears poised for growth in the coming years. This approach breaks down various waste materials, such as plastics, municipal solid waste, tyre rubber and common biomass feedstocks, using heat ranging from 300 degrees Celsius (°C) to 600°C, in the absence of oxygen.

The primary output is pyrolysis oil, also referred to as bio-oil or bio-crude, alongside fuel gas, char and hydrocarbons. Pyrolysis oil can be used in second-life plastic products or upgraded into chemicals and transportation fuels such as gasoline, diesel, and jet fuel. Additionally, syngas derived from pyrolysis can be further processed to produce renewable hydrogen.

Advocates of pyrolysis claim it has the potential to solve the crushing problem of plastic waste, leaving less waste than traditional recycling and minimising the amount of plastic and toxic components in landfills, waterways and incinerators. Pyrolysis may also reduce our reliance on fossil fuels for transportation and offer a renewable alternative for industrial applications. 

Although pyrolysis recycling shows promise, it is not without its challenges. There are still issues around the variety of feedstock, and currently, no standards exist for raw materials used in pyrolysis. Pyrolysis is also only available on a small scale, making hardly a dent in the estimated 400 million metric tons of plastic waste generated globally each year. 

The oil produced from plastic waste has a 20% lower flash point compared to regular diesel at under 40°C, increasing the possibility of spontaneous combustion, according to an article by leading risk advisor, Marsh McLennan. While pyrolysis produces useful liquids, it can also generate undesirable waxes that require further breakdown.

Oil majors and large chemical companies, aware of the obstacles in a pyrolysis-based recycling system, are making big bets on pyrolysis as they look to integrate renewable feedstocks into their processes.  

Since 2019, Shell has invested in pyrolysis technology to tackle plastic waste reduction. That same year, Shell Energy and Chemicals Park in Norco, Louisiana, U.S.A., began using oil produced through pyrolysis. In November 2019, Shell announced a bold ambition to use one million tons of plastic waste in its global chemical plants annually by 2050.

The addition of a new pyrolysis oil upgrader at Shell Chemicals Park Moerdijk in the Netherlands is underway. The upgrader will have a capacity of 50,000 tonnes per annum, with production expected to start in 2024. Shell announced numerous strategic cooperation agreements in 2023 to improve access to plastic waste feedstock and enable the long-term storage of pyrolysis oil.

ExxonMobil has been operating an advanced recycling facility in Baytown, Texas, U.S.A., since December 2022. The facility is one of the largest in North America, with the capacity to process 80 million pounds of plastic waste per year. The energy major says 45 million pounds of discarded plastic was processed by March 2024.  According to the company website, ExxonMobil is targeting one billion pounds of plastic waste processing capacity globally by 2027.

On May 6, ExxonMobil announced plans for a second advanced recycling unit at the Baytown facility, in response to rising demand for circularity.  The company has previously indicated it is considering facilities in the United States, including Baton Rouge, Louisiana; Beaumont, Texas; and Joliet, Illinois; as well as in Belgium, the Netherlands, Singapore and Canada.

In Malaysia, PETRONAS Chemicals Group Berhad (PCG) is advancing its plastic waste chemical recycling capabilities by converting end-of-life plastics into pyrolysis oil. In October 2023, PCG announced it had reached the final investment decision to construct a plant in Pengerang, Johor, with a capacity of 33 kilo-tonnes per annum. The plant is expected to be operational by the first half of 2026.

Neste, a leading producer of sustainable fuels and renewable feedstock solutions, has invested EUR111 million (USD124 million) to build capacity to upgrade 150,000 tons of liquefied waste plastic into high-quality petrochemical feedstock at its Porvoo refinery in Finland. The project has received support from the European Union Innovation Fund and is expected to be finalised in the first half of 2025. In April 2024, the Neste refinery completed its first trial processing pyrolysis oil derived from discarded tyres into high-quality raw material.

Despite increasing interest in pyrolysis as a solution to the crippling problem of plastic pollution, and the potential to limit our use of new fossil fuels, the technology is not without its detractors.  Some critics have labelled pyrolysis as false recycling, pointing to longstanding issues with the technology.

In March 2024, Shell published its 2023 Sustainability Report, which included a key admission: the company had stepped back from its earlier pledge to convert one million tonnes of plastic waste annually into pyrolysis oil, which it now deems “unfeasible.” Shell cited factors such as a lack of available feedstock, slow technology development and regulatory uncertainty. The energy major continues to emphasise its commitment to enhancing circularity.

Some states have opened their doors to pyrolysis as a solution to plastic waste through supportive legislation. Other jurisdictions, such as California, do not recognise it as recycling at all. In May 2024, the U.S. Environmental Protection Agency (EPA) rebuffed lobbying efforts by the chemical industry to relax clean-air regulations on advanced recycling of plastics, including pyrolysis and gasification.

Environmentalists have been particularly critical of the emerging recycling method. U.S.-based website Cleantechnica, which is dedicated to aggregating news in clean technology, has labelled pyrolysis as a “fairy tale,” arguing that companies rely on “mathematical acrobatics” to create the illusion of success. 

There are accusations that the method is a greenwashing scheme, with a lack of transparency around how much plastic is recycled. Some opponents have even claimed producing pyrolysis oil from used plastic contributes higher greenhouse gases than extracting crude oil from the ground.

Taylor Uekert, a researcher at the National Renewable Energy Laboratory (NREL) in Golden, Colorado, U.S.A., suggests that fuel derived from plastics fails to meet the fundamental criteria for biofuels or renewable fuels. “Plastic is not an infinitely renewable resource,” he says. 

In April, Encina Development Group announced it would shelve a proposed USD1.1 billion pyrolysis facility in Point Township, Pennsylvania, U.S.A. “While we did have challenges with the Pennsylvania permitting process, ultimately, our decision was based on increased customer demand for our products. This increased demand prompted a careful analysis of our current site plot and we found that the size would no longer enable us to build and scale to the capacity needed to meet demand,” said ENCINA Chief Communications Officer Alison Jahn.

“Community pushback did not play a role,” as previously reported, said Jahn.