TERU Focus Report -
Plastic-Aluminum Packaging Conversion
Enval Limited Untangles Tough Packaging Challenge
December 30, 2014 --
The path from
University research team discovery to commercial waste conversion is arduous and usually fraught with "chicken
& egg" challenges. The following review appeared as a Research review by the University of Cambridge, United
Kingdom, earlier this month. The challenge: cleanly and economically separate and recover the useful materials used
in plastic-aluminum laminate packaging. The technology is microwave-driven pyrolysis. The initial discovery came
about because someone over-microwaved a "bacon roll"…
Technology developed at the University of Cambridge lies at the heart of a commercial process that can turn
toothpaste tubes and drinks pouches into both aluminium and fuel in just three minutes.
It started with a bacon roll and a microwave oven, and
now it's poised to transform the recycling of a packaging material that has been as unrecyclable as it is useful.
The bacon roll, as the story goes, was microwaved for so long it turned into a charred mass of carbon that began to
glow red-hot. What was happening was an intense heating process called microwave-induced pyrolysis. On hearing
about the "over-microwaved" bacon roll from an acquaintance, chemical engineers Professor Howard Chase and Dr
Carlos Ludlow-Palafox (a PhD student at the time) at the University of Cambridge wondered whether the process could
be exploited to recover useful materials from packaging wastes. Particulate carbon is an efficient absorber of
microwaves and can transfer this thermal energy to adjacent materials. If the adjacent material is organic, such as
plastic or paper, it breaks apart (or pyrolyses) into smaller pieces; if the material is a metal attached to the
plastic or paper, the metal can be recovered in a clean form after the attached organics are
Fifteen years later, the technology they developed is
now being used in a commercial-scale plant designed, built, and operated by Cambridge spin-out Enval Limited.
Founded by Ludlow-Palafox, with Chase as R&D Director, Enval is using the plant to demonstrate the capabilities
and economics of the process to investors and waste handlers. Enval has focused on plastic–aluminium laminate
packaging. Prized by manufacturers for its lightness, low cost, and ability to protect the contents from light and
air, the packaging is commonly used for food, drink, toothpaste, pet food, and cosmetic products. However, the
combination of plastic and aluminium in the packaging presents a technical recycling challenge that until now has
been unsolved. Items packaged like this contribute to the millions of tons of rubbish disposed to landfill each
year. For the brands who package their consumer goods this way, the "recyclable logo" on the packaging, and the
sustainability credentials that go with this, have been all-elusive.
"We have carried out a life-cycle assessment of the
packaging and it’s still environmentally better to use these laminates even though they are not recyclable, just
because so little materials and energy goes into making and transporting them compared with alternatives like
glassware and cans," said Ludlow-Palafox. "There is no real drive to replace them and their market use is
increasing by about 10–15% every year. In the UK, roughly 160,000 tonnes of laminates are used per year for
packaging, which means at least 16,000 tonnes of aluminium is going into the ground. Just imagine if we could
routinely recycle this."
The solution he and Chase developed with funding from
the Engineering and Physical Sciences Research Council started in a relatively simple way: they placed a pile of
particulate carbon and some shredded laminated packaging inside a conventional 1.2 kW kitchen microwave, replaced
the air inside the oven with nitrogen and turned the microwave up to full power until the temperature increased to
about 600°C. When they opened the door two minutes later, the laminated material had been separated into clean
aluminium flakes and hydrocarbon gases and oil.
The basic chemistry is still the same in the
commercial-scale plant, but the oven is now 150 kW and large enough to be housed in a 100 m2 industrial unit. It
takes just three minutes to convert waste into aluminium for smelting, and hydrocarbons for fuel, and with no toxic
emissions. Now fully commissioned, the plant can recycle up to 2,000 tonnes of packaging a year – which, say the
researchers, is roughly the amount handled by regional waste handlers – and it generates enough energy to run
itself. Enval now has an arrangement with manufacturers of plastic–aluminium laminates to recycle their industrial
scrap at less than what they would have spent on sending it to landfill.
The researchers have, in effect, turned into commercial
waste handlers – something they would never have imagined back in the 1990s. "While we were getting into the world
of laminates it didn't cross our minds to start a company… we just wanted the process to become a reality," said
Ludlow-Palafox. "In the end, the investors [Cambridge Capital Group and Cambridge Angels] said there is no one else
who knows the process as well as you, you might as well do it! We knew that the patented technology offered a
genuine recycling route for this type of packaging but that the waste industry can be slow to take on new
technology – the margins in environmental services are small, and we needed a working, full commercial-scale plant
to convince them that the process was viable," said Chase, who estimates that a plant like theirs would pay for
itself within three years. "In parallel, we were being contacted by the brands who use the packaging, asking how
they could help."
The commercial-scale plant is partly funded by Nestlé
and Kraft Foods/Mondelez International.
"It was a chicken and egg situation," said
Ludlow-Palafox. "No one is going to buy this technology unless this type of waste is separated for recycling, but
the waste wasn't going to be separated because there has been no process to recycle it. We had to break that
negative loop somehow. Now we have the commercial-scale plant, we can show waste handlers the benefits and
encourage local authorities to implement a selective collecting system."
Meanwhile, the scientists are keeping an eye on future
recycling prospects. Research into the microwave pyrolysis of different types of wastes continues in Chase's group
in the Department of Chemical Engineering and Biotechnology. "It's crucial that we continue to look for new
opportunities for recycling valuable materials while simultaneously eliminating the need to send wastes to landfill
“We've demonstrated that a lot of troublesome waste
materials can be pyrolysed using our microwave technology but it's not always economically sensible to do it; the
challenge now is to identify which processes are likely to be commercially viable, and which of those will attract
the necessary investment funding to bring them into commercial reality. This is a business sector that is
comparatively unfamiliar to most investors who regularly commit to innovation in other areas. By demonstrating the
societal and economic benefits of green technologies, we hope to secure the necessary investment to transform
innovation into successful commercial practice."
Teru Talk has tracked Enval Ltd's efforts since the UK's Waste
& Resource Action Program (WRAP) reported in September of 2011 on the young company's work with the
industrial consortium led by Kraft.
The text in this work is
licensed under a Creative Commons Licence. The source of the review is a December 4,
2014 article published by the University of Cambridge, United Kingdom, to be found at: http://www.cam.ac.uk/research/features/where-theres-muck-theres-aluminium-if-not-brass
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Michael Theroux. http://www.terutalk.com