vendredi 3 avril 2009

Bioplastics show potential but some hurdles remain

New developments could help bioplastics emerge from its early infancy in the coming years, according to a report from Environmental Data Services, but some obstacles still remain.

Bioplastics are a form of plastics derived from renewable biomass sources, such as vegetable oil, corn starch or pea starch. However, many are reliant on fossil fuel-derived energy for their manufacturing.

While this would appear to give them solid environmental credentials, EDS identified a number of “false dawns” for the polymers eight years ago. Even two years ago supermarket Asda declared that it was switching to bioplastics… but now does not use them at all.

European Bioplastics says bioplastics make up 0.20 per cent of the total plastic market in the EU, which is estimated to weigh in at 48m tonnes per year.

However EDS believes that the polymer’s time may have come at last, as early performance problems have been addressed, and manufacturing has become more efficient.

One example is the possible introduction of plant-derived non-biodegradable that are said to be “functionally and chemically identical to their oil-derived counterparts”, such as Brazilian bio-propylene from sugarcane ethanol. Such materials would be able to fit into existing processing and recycling structures, EDS notes.

Another is a polylactic acid (PLA) product from Natureworks in the US, which launched new fermentation technology in 2008 that significantly reduces carbon emissions in line with those of recycled polyethylene terephthalate (rPET). Moreover its lower density is said to mean less material is needed for the same strength product.

End of life hurdles

European Bioplastics optimistically projects that the bioplastics market in Europe could reach 5m tonnes by 2020, some 10 per cent of the total plastics market (as it stands today). This would require growth in the sector of 35 per cent per year.

Despite the potential, there are still some significant hurdles to bioplastics becoming a big hit – not least what to do with them once their useful life is over.

“The bottom line is that while many bioplastics do appear to offer substantial environmental gains over conventional materials, much depends on whether they end up being landfilled, incinerated pr composted, and how different environmental objectives are weighted,” said the ENDS report.

While bioplastics that are not incinerated or routed to landfill are likely to be composted and should, in theory, be accepted by composters, often they are not out of concern that they could be contaminated with conventional plastics.

Another option could be anaerobic digestion, whereby the packaging could be fed into digesters together with waste food. However there is still limited capacity for this form of disposal, and many bioplastics manufacturers are still conducting tests.

Food price issue

At the recent PCD Congress in Paris Professor of Bio-polymer Science and Engineering Stéphane Guilbert warned that materials used for making bioplastics are often derived from sugarcane and cornstarch – important sources of food.

By harvesting these crops to make packaging, environmentally-conscious companies could be inflating food prices in developing countries, he said.

However a spokesperson for European Bioplastics told last year that bioplastics have no impact on the food supply and availability situation, and technical solutions to use mainly non-food crops in their manufacturer are under investigation or already in use.

She called for all parties involved in their production to support sustainable development of bioplastics, and to take into account that no raw material has unlimited availability and therefore the most efficient use of resources must be achieved.

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