Not all plastics are created equal

by Alan Matchett. Published Tue 02 Jul 2013 11:26
Tackling the plastic issue
Tackling the plastic issue

In the current economic climate, it seems fair to say that environmental concerns have slipped a rung or two on people’s ‘worry ladder’. They have certainly not, however, disappeared off the bottom and hit the ground with a terminal thud. Their grip is firmer than that. Customers still want to be ‘green’ if and when they can. This poses a problem for the plastics industry with its ‘bad rep’ when it comes to saving the planet. But are all plastics bad and how can the average customer separate fact from fiction when it comes to plastics and the environment?

It’s vital to understand two things: not all plastics are created equal and the answers are not always as obvious as they first appear.

Plastic is a key building block of our modern world. It’s everywhere; from the computer keys with which I’m typing this piece, to the café chair I’m sitting on, to the striplights above my head. It really is everywhere and it accounts for 12.4 per cent of our total waste. So finding the most environmentally friendly version possible is of obvious importance.

Broadly, the prospective purchaser is faced with three alternatives: biodegradable plastics, degradable and compostable plastics.

Biodegradable simply means capable of being broken down by bacteria or other living organisms. These ‘Bioplastics’ are made from natural materials such as corn starch. Surely this is the greenest option? Well, as I mentioned earlier, in the green minefield the apparently obvious path is not necessarily the right one. The problem is methane gas, a gas with a staggering potential impact – more than 60 times the global warming potential, or GWP, of carbon dioxide. If biodegradable plastics are simply pushed into a landfill site, they ‘good’ bacteria can be buried under layer upon layer of other waste. Without oxygen, they die and a different form of decomposition takes place. Known as anaerobic (without air), this process produces large amounts of methane; not good. One other problem with starch-based plastics is finding the raw material. Removing from the food chain, the amount of corn etc that would be needed could have a catastrophic impact on the food supply chain in our increasingly overcrowded world.

Degradable plastics are, essentially, another form of biodegradable plastic. But these are made from the more common petrochemical starting point and then have more chemicals added which help them to break down. These plastics can metabolise completely in anaerobic conditions without the methane problem, producing only water and carbon dioxide.

Compostable is a term often mixed up, even by manufacturers, with biodegradable. Compostable means, well, exactly what it says; when it breaks down, it will produce compost, a stable, organic substance which contains no toxins and supports plant life. Simple. Well, simple-ish. As so often, the devil is in the detail with arguments over definitions and reasonable requirements. There is also the problem of how to produce compostable plastics. Currently, the energy demands of doing so can mean that more fossil fuel is used than would be to produce the equivalent amount of the ‘less green’ petrochemical alternative.

So, the choice is not a simple one. One last thing worth thinking about – plastic munching bacteria. It sounds a bit far-fetched, but nylon eating bacteria have already developed and it’s widely accepted that bacteria have probably developed the ability to consume hydrocarbons.

Author Bio
Alan Matchett provides articles online for IPSLUK covering helpful tips on DIY, home improvement and construction.

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