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Is the future of polythene surprisingly green?

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As the EU debates introducing a mandatory charge on single use plastic bags, Anthony Brimelow,  commercial director of polythene manufacturer Duo UK, takes a look at how technology is helping to 'green'  a material that's often viewed as an environmental L'Enfants terribles.

Although the EU proposal to introduce a mandatory plastic bag tax is unlikely to receive the unanimous backing it needs, it is the latest in a series of measures designed to curb the use of single use plastic bags, which are often perceived by politicians and the general public as being environmentally harmful.

Setting aside the 'science' behind the proposals for now, what seldom seems to be recognised is the fact that single use polythene bags are just one, relatively small, incarnation of the world's most common plastic. Polythene is deeply ingrained in our world - it's used in everything from shampoo bottles to medical equipment to bullet proof vests, - so it seems a fair bet that it's going nowhere fast. Given this state of affairs, I'd argue that it makes far more sense to minimise the environmental impact ofallpolythene, rather than concentrate so much effort on trying to dissuade the public to use just one polythene product. (And for the sake of clarity, no, single use carrier bags aren't a significant part of our business!)

In truth, a lot is already being done within the polythene industry to firstly make the production process of polythene as efficient and waste free as possible, and then to recycle used polythene in better and more creative ways. There's also promise of more improvements on the horizon, including switching from oil - the raw ingredient of polythene - to a sustainable alternative.

Measures such as gravimetric dosing used during the production process, are instrumental in cutting waste and reducing the amount of virgin material required. The technology works by weighing the raw materials of polythene as they are dosed directly into the extruder, thereby virtually eliminating the need for 'pre-mixing ' from the process.  The result is a more accurate blend which generates less scrap and uses less energy.

As well as improving the manufacturing process, responsible manufacturers have realised the good business sense of working with clients to reduce the amount of packaging they need - thereby saving them money - and to implement effective recycling processes.

At Duo we do this by offering clients an annual onsite packaging audit where we analyse the products used and goods shipped and advise on the best range of packaging to minimize both waste and cost. We also implement active stock management which, combined with the short lead times of our UK-based manufacturing operation, means we can forward plan transportation to deliver products in bulk, thereby reducing road mileage.

Recycling is another area where we work closely with our clients. We predict the demand for recycled products to increase dramatically over the next few years, driven largely by consumer demand and by improvements in technology.

Previously recycled polythene could be less consistent than its virgin counterpart and its smell - think bin bags - limited its application. Both these problems are caused by contaminants  in  the polythene blend, but work we've done in our quality control lab has helped to eliminate these problems, so much so that we've just launched an 'odour free' recycled mailing bag line.  In addition to being used in standalone products, recycled polythene also has numerous other applications including on the inner layers of multi layered -or co-extruded - polythene, which itself has various benefits.

We've seen so much growth in demand for recycled products that we've recently invested in a second closed loop recycling machine and we're working with clients to encourage them to make use of it. We collect waste from our customers and pay them per tonne, however despite these steps we still need to go to third parties to buy more scrap to meet demand.  We know many companies which are otherwise keen to recycle are hampered by waste contracts and this is one area where concerted industry-wide effort is badly needed.

On top of the measures which have already been implemented, there are also exciting developments on the horizon. Just a few months ago we signed an agreement with international polymer distribution company Resin Trade Ltd, to be the first UK-based manufacturer to produce mailing bags using Green PE, a thermoplastic resin made entirely from sugarcane ethanol.

Green PE itself has been developed by petrochemical producer Braskem, and means we can now offer customers a product which is created from 100% renewable material, which is also 100% recyclable. What is particularly exciting about Green PE is its environmental credentials extend all the way down the production chain. The raw ingredient sugarcane is a water efficient crop that also captures carbon dioxide during photosynthesis and is planted and grown in accordance to strict ethical guidelines. Further CO2 is sequestered from the atmosphere by the ethanol used to make Braskem's green polyethylene. As a consequence, each kilogram of green plastic produced using this method saves 2.15kg of CO2, when compared to the production of conventional oil-based polythene.

Meanwhile, from a manufacturing point of view, we can use the same processes and machinery we use to create standard polythene products, which makes it a very practical product.  Having said that, there is no denying that Green PE, like many new technologies, is currently more expensive than its standard equivalent. Nonetheless it is a great example of how technology can radically reduce the environmental impact of a product, assuming that there is the appetite to do so.

Of course, so far we've discussed how the environmental impact of polythene can be lowered both now and in the future, rather than comparing the environmental impact of polythene to other packaging materials. Given legislators' ongoing determination to crack down on single use plastic bags compared to other forms of packaging, it's entirely understandable that the average consumer would think plastic bags are particularly environmentally damaging, however the science simply doesn't support this. 

An Environment Agency report* which was published in 2011 compared seven types of bags,  and found that single use carrier bags had the lowest environmental impact in nine out of 10 impact categories. The same report showed that paper bags would need to be reused four times and cotton bags 173 times, in order to ensure they have lower global warming potential than a normal single use carrier bag.

Given these facts I would argue that placing so much emphasis on reducing single use carrier bags is a red herring.  The science simply doesn't stack up and of course it does nothing to address the vast quantities of other polythene being produced for other purposes.  A more productive approach would be to encourage the industry to maximise efficiencies and minimise waste in producing all types of polythene and to explore, develop and commercialise new technologies. Given these parameters, I'd say yes, the future of polythene is green.  Whether it's 'surprisingly' so, depends on where you're coming from.

 

* Life Cycle Assessment of Supermarket Carrier Bags, Dr Chris Edwards and Joanna Mehoff  Fry https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/291023/scho0711buan-e-e.pdf

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