Environment

Asda packaging buyer Shane Monkman has characterised the current performance of and end-of-life questions around compostable packaging as "a really grey area". He's so sceptical, in fact, that he's decided not to use them.

With green issues at the top of every buyer's agenda, packaging that can be safely disposed of on a garden compost heap sounds like a perfect solution. But it's not that simple. Currently, much compostable packaging requires heavy duty chemical treatment to break it down. Questions have also arisen over the availability of the raw materials – corn-starch, wood pulp or oil – which make up the bulk of compostable packaging.

Nevertheless, Asda is, by Monkman's own admission, "unique" in its position on compostable materials. Other buyers are falling over themselves to put the compostable label on their packs.

The Co-operative Food is among those taking a positive line with various types of degradable material. Commercial packaging manager Iain Ferguson explains that home-compostable film is used for some carrier bags. "We also have compostable materials on some of our organic produce," he says. "These are materials such as [Novamont's] Mater-Bi and cellulose (wood pulp-based) film. We do not use polylactide (PLA) because of its GM status and because it cannot be home-composted."

Compostable packaging makes most sense around organic produce, the Co-op argues, where consumers are more likely to be active composters. Ferguson adds: "We would be much less likely to use it in areas where we were less convinced of these criteria, such as in ready meals."

Adding to the murkiness of Monkman's "grey area" are oxo-degradables. These are conventional oil-based polymers dosed with an additive which causes them to break down under particular conditions of heat, light and air. As such, they have the advantage of being converted in the same way as standard films.

Champions of packaging complain that it is targeted for disproportionately tough treatment by ministers and the media because of its visibility. If so, then oxo-degradable films seem to be the flip side of this coin, and proof that 'out of sight is out of mind'. The additive – "mainly cobalt salts or other heavy metal compounds," says BASF – causes the film to break into tiny fragments. The films 'degrade' in that sense, but do not change their chemical composition, and do not 'biodegrade' in any meaningful sense at all.

Positive characteristics
But if there is any substance to the idea of 'second generation' biopolymers, it is in the way new properties are being developed, either by combining different base materials or by modifying the properties of the principle material.
Innovia Films says it will soon have a version of its Natureflex film with a much improved moisture barrier. As market development manager Andy Sweetman says: "The film will be suitable for dry foods such as biscuits, snacks and confectionery."

When it comes to PLA, European business development manager at NatureWorks, Mark Vergauwen, cites several examples of modified properties. "For example, the most exciting development at the Interpack show was the ability to combine softness or stretch with clarity for the first time," he recalls.

In September, the NatureWorks-sponsored Innovation Takes Root conference in the US heard from, among others, suppliers of calcium-carbonate, acrylic and nano-scale modification technologies. These have the potential, at least, to offer new strength and barrier characteristics to materials such as its Ingeo PLA.

Availability of supply has been another area of concern. It has led some retailers such as Marks & Spencer to sound out the viability of sourcing PLA and similar materials from China. NatureWorks now admits the 140,000-tonne 'nameplate capacity' of its single Nebraska plant was, for many years, more concept than reality. In fact, it has only recently edged output up to 70,000 tonnes, of which around 75% is used for packaging applications.

The US company's business development manager for the UK, Eammon Tighe, explains: "If you go back 18 months, a lot of the doors we'd been knocking on opened up at the same time, so we got caught with insufficient capacity. But since then we've managed to de-bottleneck, and already boosted output by 15% or 20%."

Teijin's acquisition of a 50% stake in Cargill, the food and agricultural product manufacturer, last November will have an even greater impact on future supply. "We plan to double the current capability of the plant by the first quarter of next year," says Vergauwen. There is talk of a second plant, but apparently no agreement yet even as to whether it should be sited in Europe or Asia.

Output is increasing elsewhere, too. Earlier this year, BASF announced that it would add 60,000 tonnes to the current capacity of 14,000 tonnes at the Ludwigshafen, Germany, production plant for its Ecoflex biodegradable polymer. The new site will be up and running by the third quarter of 2010, says the company.

Unlike many biopolymers, Ecoflex is petrochemicals-based. It is said to have many of the characteristics of polyethylene, but biodegrades in accordance with the EN 13432 standard. Recognising that demand increasingly hinges as much on the product's renewable origins as its biodegradability, the multinational has begun to produce Ecovio, a blend of 55% Ecoflex and 45% PLA.

Converters as well as biopolymer producers are creating more space for these materials. Innovia, for instance, says a new line on its Wigton site will be available from early 2009. This will increase capacity for all cellulose-based films to 28,000 tonnes.

Rigid restrictions
The different perceptions and potential end-of-life scenarios for rigid and flexible formats cast another grey shadow over biodegradables. While Asda's Monkman claims that only 3% of the UK population can be classified as 'regular composters', Innovia and others quote estimates closer to 10%. Whatever the exact figure, it appears to be growing, and provides a viable outlet for flexible biodegradables in home composting.

That is not the case with rigid containers. And so long as there is no route to industrial composting or anaerobic digestion (AD), it will remain difficult to argue convincingly that these formats are 'sustainable', whatever their origin.

Of course, when it comes to PLA bottles, there are other concerns. Opponents have highlighted the potential risk of PLA contamination to existing bottle recycling, in particular polyethylene terephthalate (PET). The Co-op's Ferguson, for instance, gives this as his reason for not using biodegradable materials in drinks bottles.

While these issues have deflected UK brands such as Innocent Drinks from adopting PLA, they do not constitute a universal deterrent. Italian water brand Sant'Anna recently adopted NatureWorks' Ingeo PLA for its bottles, with the claim that the bottle will fully decompose in around 80 days "in a suitable disposal location".

Now, far from being seen as a gatecrasher spoiling someone else's party, NatureWorks is keen to explain that it can organise parties of its own. For the first time, the supplier is talking about the ease with which PLA could be recycled. The message is that, post-use, it generates multiple possibilities rather than problems.

Biodegradable flexibles are likely to have an easier ride over the coming years. To date, the arguments for protecting and lengthening shelflife have outweighed the rationale of compostability. But as the performance of biodegradable films improves, and composting and AD infrastructure strengthens, that balance could shift.