Issue 04/2023

28 bioplastics MAGAZINE [04/23] Vol. 18
Top Talk
Chemical recycling
as a reset button
D
oes chemical recycling actually reduce greenhouse
gas emissions in an overall life cycle assessment?
How does chemical recycling compare with
mechanical processes and thermal recycling?
The bi-weekly German plastics journal K-Zeitung
talked to Heikki Färkkilä, Vice President Chemical
Recycling at Neste Renewable Polymers and Chemicals.
The interview was conducted by Matthias Gutbrod
(K-Zeitung, www.k-zeitung.de).
MG: With mechanical recycling and waste-to-energy
incineration, there are established processes for dealing
with plastic waste. Why is chemical recycling necessary?
HF: Incinerating fossil-based plastic waste with energy
recovery is basically equivalent to burning fossil resources
that have taken a short detour as plastic products.
The incineration of plastic waste results in significant
greenhouse gas emissions. As progress is made toward zeroemission
alternatives for both electricity and heat generation,
the approach is becoming less convincing.
By keeping materials in circulation through recycling,
incineration and other scenarios such as landfilling or, in
the worst case, littering the environment can be avoided.
Mechanical recycling is indeed an efficient and proven method
to achieve this. However, it has its limitations. There are
waste streams that are very difficult or impossible to recycle
mechanically. In addition, there are medical or food contact
applications that cannot be covered with mechanically
recycled material for reasons of quality and purity. In other
applications, the recycled material must be mixed with virgin
plastics to achieve the desired quality.
In all of these cases, chemical recycling can come into play
by expanding the range of recyclable waste, allowing the use
of recyclates in sensitive applications, and replacing new
plastics in the mixtures with recycled plastics.
MG: Critics say chemical recycling is very energy-intensive
and the material yield is low. What counterarguments can
be put forward here?
HF: There is no doubt that chemical recycling is more
energy-intensive than mechanical recycling. However, it
also processes other waste streams and produces other
products by turning hard-to-recycle plastic waste into virgin
raw materials for new plastics. In terms of energy intensity,
pyrolysis-based liquefaction processes can obtain most of
the required energy from non-condensable gases generated
as a side stream from the waste itself. This minimizes the
need for additional energy. In terms of yield, up to 85 % of
the polymer content of waste plastics can be converted into
pyrolysis oil, which is then further processed into feedstock
for new plastics in very efficient, large-scale refineries.
MG: Chemical recycling could process various types of
mixed plastic waste, but to achieve high yields with justifiable
energy input, fairly clean and homogeneous plastic waste is
required. Do chemical and mechanical recyclers ultimately
compete for high-quality waste after all?
HF: If plastic waste is suitable for mechanical recycling,
it should be recycled mechanically in the first place.
Anything else would be economic nonsense. It is true,
however, that chemical recycling cannot accept every material
either. We will mainly be looking at polyolefins that have little
or no value for mechanical recycling due to impurities, dyes,
multi-layer or multi-material structures and the like. Neste is
expanding the range of chemically recyclable materials by
using its own processing technologies as part of the ‘PULSE’
project supported by the EU Innovation Fund (cf. page 10 in
this issue of bioplastics MAGAZINE - MT).
MG: Which waste fractions would even a chemical recycler
ultimately no longer want to recycle?
HF: Chlorine is one of the substances that cause difficulties
in chemical recycling processes. Therefore, materials such
as PVC will have to continue to wait for a recycling solution.
We would also sort out PET because there is already a wellfunctioning
recycling infrastructure in place.
It is interesting that you talk about “no longer” in your
question: Every time a material is mechanically recycled,
the quality decreases somewhat, which means that it
cannot be recycled infinitely this way. Chemical recycling
basically provides a reset button that restores the quality of
the material, so that it can then be mechanically recycled
again several times. This once again underscores the
complementary nature of both routes.
MG: Chemical recycling is considered costly due to preprocessing,
energy requirements, and the use of chemicals/
catalysts. Under what conditions can chemical recycling be
operated economically?
HF: The cost issue has brought us to where we are today:
With our backs to the wall against climate change. It is not
only with plastics that we have chosen the seemingly cheap
fossil route. But fossil resources are only cheap because
we ignore the consequential costs. Yes, more sustainable
alternatives are more expensive in most cases, but they are
also just more sustainable.
Fortunately, there are well-known brands and a growing
segment of consumers willing to value more sustainable
solutions. At the same time, regulation is also evolving,
which is necessary to accelerate the adoption of new circular
economy solutions. In general, we expect the cost of chemical
recycling to come down as the technology learning curve
and volumes increase.