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Youth Perspective: Green milk? Barriers to technological sustainability solutions

Thomas Attree

12 Oct 2016

Can technology save the planet? This is a very broad question, but one which was recently posed at the One Young World summit in Ottawa. As I sat in the audience whilst the panel were discussing this topic, an overwhelming frustration struck me. As a technologist, I know that we already have many technological solutions which can save the planet. One such example is milk bottles.

In the UK, milk is typically bought from supermarkets in high-density polyethylene (HDPE) bottles. HDPE is an extremely recyclable thermoplastic, but milk bottles are rarely made from fully recycled HDPE. Why is this the case?

It is all to do with the colour of a bottle made from 100% recycled material. Our milk bottles would turn an unappealing shade of off-green. To understand why this is the case, we need to look at the process. The most popular milk type in the UK is semi-skimmed, sold with a green label and green HDPE lid. Recycled milk bottles get shredded in to fine flakes, often with the lid still screwed on. These shredded flakes then fall through a light beam which determines the flakes colour based upon the reflected light. Using this information, further down the waterfall of plastic, air jets fire at just the right moment to blow particular colours into a separate bucket. All whilst the flakes are falling from the top of a chamber to the bottom. Pretty cool tech right?

As awesome as this process is, it isn’t 100% accurate. Not all of the coloured fragments get an air shot and some end up in the mix of clear plastic. This in turn gets melted and moulded into new bottles, giving the overall result a slight green tinge.

What frustrates me is we have the technology to consider milk bottles as a closed loop sustainable product. A product in which we can recover 100% of the used, waste material, and convert it back into another bottle. We have refined enough crude oil for all of our milk bottles to be made from fully recycled HDPE. But what about that green tinge?

Supermarkets probably know more about their customers than any other business, and supermarkets believe that consumers would not buy milk if the bottle made it look a whiteish-green. This is an understandable viewpoint; would you buy off green milk without knowing why it looked off green in the bottle?

Maybe there is another solution. What if the bottles had clear lids? The supermarkets have an answer for this too. In that it takes customers less than a second to identify the brand and type of milk they want to buy. A clear lid would confuse and be detrimental to sales. How can we override these subconscious decisions? Is it about informing the customer why the bottles are green or the caps are clear? Who would pay for such a marketing and educational campaign? Many questions that sadly I cannot answer.

So how do the supermarkets make their bottles clear? Many milk bottles are made of predominantly recycled materials. The colour imbalance is corrected with the addition of new raw product, refined from crude oil. In recent times crude oil has been cheap. Cheap enough to almost forget about the remarkable recycling technology all together. When the oil price is low it is cheaper to make anew than to recycle what we already have. Even though we have technology to close the loop on milk bottles. The technology which means we don’t need to produce any more HDPE from crude oil. Think about that for a second; it is cheaper for us to make anew than to recycle what we already have. But what is the real cost of manufacturing new bottles? One day our planet will run dry and we will be reminiscing of the time our milk came in clear bottles.

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