CHEMICAL RECYCLING | PYROLYSIS PROJECTS


LCA comparison of CO2 emissions between pyrolysis and incineration of mixed plastic waste. Source: BASF


circular polymers is saving around 2kg of CO2


LCA comparison of CO2 emissions between production of LDPE from pyrolysis oil and naphtha. Conventional production of one tonne of LDPE emits, in total, 1,894 kg CO2e. For the production via pyrolysis, a negative number of -477 can be accounted for overall CO2 emissions. Source: BASF


per


kg of polymer compared with fossil-based virgin polymer. This is shown in a life cycle analysis (LCA) the company has produced, similar to the one produced by BASF and others. “There is a clear imperative to scale advanced


recycling as a complementary technology to mechanical recycling,” says Dow. It views it as anoth- er potential game-changing moment that will be critical to meeting the EU’s legally binding plastics packaging recycling targets of 55% by 2030. Dow says its investment in, and increased use of both chemical and mechanical recycling technolo- gies is supported by data which proves its effective- ness and sustainability. “It has been shown that


recycling saves between 30% and 80% of the CO2 emissions that virgin plastic processing and manufac- turing generate,” it says. “If all plastic were recycled this could result in mean annual savings of 30m to 150m million tonnes of CO2


, equivalent to shutting


between 8 and 40 coal-fired power plants globally.” In a position paper on the state of the art in science and technology of recycling technologies for plastics issued in September, the Fraunhofer Cluster of Excellence Circular Plastics Economy (CCPE) provides an overview of mechanical and feedstock (chemical) processing technologies for plastics that are currently under development. Prof. Matthias Franke, head of the Sulzbach-


Rosenberg branch of Fraunhofer UMSICHT, primarily develops pyrolysis-based recycling technologies. He says: ““We believe that new recycling technologies are technically capable of meeting the additional demand for high-quality recyclates. There is still a need for development,


16 PLASTICS RECYCLING WORLD | November/December 2021


especially for complex wastes such as composite materials. An overall ecological assessment of the processes is also still pending.” Regarding the current state of industrial applica-


tion, Alexander Hofmann, Head of the Research Department Advanced Recycling at Fraunhofer CCPE, says: “There are only a few large commercial [chemical recycling] projects so far. Therefore, there is a lack of empirical data on the long-term opera- tion of plants, reliable data on mass and energy balances and on economic efficiency.” In addition, Hofmann says, industry projects for chemical recycling have so far been designed for relatively pure waste materials. Mixed plastic waste or composite materials have so far been consid- ered less often as feedstock, even though there is considerable raw material potential here as well. “There is still need for technical development before high-quality recyclates can be produced from these material flows on an industrial scale.” TNO, the Netherlands Organisation for Applied Scientific Research, has developed a model called PRISM (Plastics Recycling Impact Scenario Model). “This is something that we further develop now also with governments and investors and parties interested from industry,” says Pieter Imhof, who heads a unit working on circularity of plastics. “We see that chemical recycling needs to be more robust with respect to the quality of the feedstock, so that a stream that currently goes to incineration could go to chemical recycling. We need to develop a technology further that can tolerate dirty feedstock and a larger variety of polymers in feedstock to get higher efficiency. This is where we are concentrating our efforts.”


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