Bioplastics: The "Other" Biofuel?
If there's one thing we've learned over the last few weeks, it's that burning large quantities of staple foods to produce a relatively small amount of fuel is a thoroughly misguided practice -- with grave implications for the world's most vulnerable populations. And though the barbs directed at biofuels from all sides have been merited, we must not forget one of the other main culprits in this global food crisis: bioplastics. A new Guardian study reported on by environment editor John Vidal reveals that efforts by industry and supermarkets worldwide to replace conventional plastic with bioplastic bags made from plants has caused consternation among environmentalists and consumer confusion. These bags, which are typically made from corn, wheat or sugarcane, may increase GHG emissions, the study found, because they either require higher temperatures to decompose or can't be recycled -- and therefore end up clogging landfill sites.
Corn-based bioplastic packaging is made with polyactic acid (Pla), which closely resembles typical PET (polyethylene terephthalate) plastic, is widely used by large food groups and grocery chains, including McDonald's and Wal-Mart, and bottlers. Though proponents claim Pla helps extend products' shelf life and cut emissions production during the manufacturing process, the study found that it barely broke down and could only be composted in anaerobic digesters, all of which do not take packaging. Pla bags that end up on landfill sites release methane, a very potent GHG, when they degrade.
Moreover, its inclusion in recycling operations can contaminate the other materials and make recycled (conventional) plastics unsaleable. To handle bioplastic packaging, recycling companies would need to invest in very expensive, cutting-edge machinery that could extract the Pla from waste.
Then there is the problem with so-called "oxy-degradable" plastic bags, which supermarkets are promoting as the "sustainable" alternative to PET bags. Although it's true that these bags, which contain an additive that facilitates the breakdown of plastic, are, in fact, biodegradable (in principle), the fact that they eventually end up in an anaerobic landfill site means they won't degrade effectively.
As Chris Goodall, an environmental author and analyst points out: "People think that biodegradable is good and non-biodegradable is bad. That's all they see." In practice, that distinction is not always so evident. As with biofuels, we need to find better alternatives to feed stocks and ensure that the bags degrade properly -- both not easy objectives. Perhaps more bags made out of cow poop?
Via ::The Guardian: 'Sustainable' bio-plastic can damage the environment (news website)