The Plant Age - can we move on from plastic?
If the Stone, Bronze and Iron Ages define early human technological development, then our descendents in future millennia will probably refer to the late 20th Century as the plastic age, considering the billions of tonnes of the stuff that have been consigned to landfill.
No other material has replaced such a wide range of natural and biodegradable alternatives, particularly in food packaging and storage applications: wood, straw, paper, cardboard, ceramics, glass and natural rubber have all been replaced by plastic alternatives. In fact, unless you are reading your copy of Materials World wearing only your cotton underwear in the middle of a field, I’ll wager you can count at least 10 objects either wholly or partly made from plastic just from where you are sitting.
The reasons why will be fairly well understood by most readers – plastic is strong, lightweight, mouldable, waterproof, easy to clean and sterilise, durable and long lasting. But therein lies its biggest problem – some plastics are very, very long lasting. Take a petroleum-based plastic such as polyethylene terephthalate, or PET, used to make most containers and bottles. It will not biodegrade. The only way PET breaks down naturally is by photodegradation, whereby the UV rays in sunlight break down the bonds holding the long molecular chains together. But unlike biodegradation, in which bacteria effectively turn a material into ordinary, natural compounds, photodegradation is simply breaking the plastic into ever smaller particles rather than transforming it into something else. Once buried in landfill, even photodegradation will not take place because there is no sunlight to initiate the process.
To be totally environmentally friendly, a product needs to be compostable. This is similar to biodegradation, although composting not only breaks down a product but also turns it into humus, which provides valuable nutrients to the soil. According to the US Federal Trade Commission, for products to be certified as compostable ‘All the materials in the product or package will break down into, or otherwise become part of, usable compost in a safe and timely manner’. Compostable products should typically break down over one to four months, depending on the composting technique, the product size and material used.
Our need for disposable food packaging is not going to reduce, so what can be done to replace the ubiquitous styrofoam cup, plastic water bottle and sandwich box? One solution is Vegware, a Scottish manufacturer of cellulose-based food packaging and catering disposables. As part of this year’s World Environmental Day in June, I attended a product demonstration event and was amazed to learn that every possible type of packaging and container used by the take-away and fast food industry is now available in a compostable form. In an encouraging example of joined-up thinking, specialist organic waste collection recycling is also available in many parts of the UK to provide a completely green life-cycle, with the waste and plant-based packaging being composted and spread on fields to become new plant growth.
So what is stopping plastic and polystyrene packaging being consigned to the waste bin of history? Well, unsurprisingly, vegetable-based alternatives cost more than conventional oil-based plastics and landfill waste disposal is still too convenient, so the major fast food chains have no real incentive to change. But increasing landfill taxes, rising oil prices and good old public pressure might yet force a change of policy. Maybe one day future generations will identify this as the start of the Plant Age, although ironically as the products are supposed to be 100% compostable, there shouldn’t be any evidence to show for it.