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How Green Are Those New Cassava Bags?

— August 24, 2017

An Indonesian entrepreneur began manufacturing bioplastic from starch to solve his country’s waste problem, but are cassava bags really a “green” solution?

Southeast Asia is awash in plastic waste. Strong economic growth combined with the usual suite of externalities (that is, it would have cost somebody something to clean up all that plastic) means that Balinese beaches and the bellies of sea creatures alike are filling up with plastic flotsam. One Indonesian entrepreneur is looking to solve the problem by using cassava, a fast-growing and inexpensive food crop, to formulate a new take on the ubiquitous plastic shopping bag. But how green are these new cassava bags? Let’s take a look.

Kevin Kumala started studying the manufacture of bioplastics after he and a friend sat at a bar watching traffic pass by in a rainstorm. All at once, he realized that the cheap, disposable plastic ponchos that the motorcyclists were wearing would be used, at best, a few times before they were thrown away, but that they would never really decompose. Unless it’s been incinerated, all the plastic we’ve ever used is still with us, somewhere. In coastal areas, like Indonesia, light plastic waste often finds its way into the surrounding sea. It looks terrible, but even worse, it’s a danger to ocean animals, and works its way back up the food chain to us.

Kumala eventually launched Avani Eco, a company that began manufacturing alternative rain ponchos made from bioplastic. Unlike the usual kind of plastic, which is made from petrochemicals and requires oil or natural gas as a feedstock, bioplastics rely on renewable materials such as corn, soy, or in this case, cassava and vegetable oil. Avani Eco branched out from the poncho business and now makes “plastic” bags. These cassava bags are designed to decompose over a period of several months when exposed to the elements, but also dissolve quickly in hot water. Kumala has demonstrated their nontoxic qualities by melting them in water and drinking the result.

While 10 out of 10 sea turtles would rather nom on one of Kumala’s cassava bags than on its petrochemical equivalent, will bioplastics solve other problems for our planet? On the surface, they seem like a step in the right direction. However, bioplastics have their own problems, which are seldom given due consideration by those whose consciences are eased by the presence of a seemingly ecological alternative to standard plastic.

One thing to watch out for is how these cassava bags (and other bioplastic materials) actually cycle through the waste stream. Nothing like this plastic decays in a landfill, of course. Some bioplastics are not actually degradable, and the ones that are theoretically compostable require the high temperatures and frequent turning of an industrial composting facility. Home composting will not work. When bioplastics are tossed in with the rest of the plastic recycling stream, they interfere with recycling that batch of plastic, or result in a lower quality recycled product. Adding yet another fringe form of plastic to the recycling stream complicates the process, and none of the other solutions are very good, either. If we wanted to create a kind of plastic for which the best disposal option really is to throw it in the ocean or tangle it in a tree, this may be it.

A compostable, corn-based bioplastic cup after two years of home composting.
Zane Selvans cycled this corn-based “compostable” bioplastic cup through his hot, active home compost pile for two years, and as you can see, not much has changed. Photo by Zane Selvans, via Flickr. CC BY-NC-SA 2.0

When using crops to make plastic, one must also consider what else that feedstock could have been made into. Crops generally have two parts. First, there’s the portion of the harvest that is used to feed people and animals (like kernels of corn), and then there’s the waste product (such as the leftover stalks). Bioplastic like the kind that forms these cassava bags is made from the edible portion of the cassava plant, the starch. Cassava is a staple food crop; some 10% of the global population relies on it as their main source of carbohydrates.

Some other industries rely on crop waste to create “sustainable” products instead of using oil, but how sustainable is it if we use petrochemical fertilizers to replace the soil nutrients that could have been returned to the soil by composting crop waste? Any time we use resources faster than they can be replaced, nothing we are doing is truly sustainable, and this practice only shuffles around the use of oil.

It may be relatively easy to grow and simple to extract the starch, but cassava has other problems looming on the horizon. Yields have been stagnant for decades (so every batch of cassava bags may represent nutrients that hungry people had to find elsewhere). Cassava is prone to brown streak disease. Also, the plant’s genetic code is decaying almost as fast as the cassava bags made from it; with about 30 mutations accumulating per generation, this is a crop headed towards GMO tinkering or extinction.

Finally, there’s the elephant in the room that only people outside the mainstream dare mention. Problems with industrial culture are impossible to solve completely by applying industrial culture to the problem. In this case, the kind of wasteful consumerism that befouls the oceans and sucks up finite resources (such as oil and even biomass) isn’t going to be solved by the industrial manufacture and distribution of almost-but-not-quite-plastic cassava bags. They clean up part of a symptom, and may even be a local solution good in tropical, coastal areas, but even then, they still rely on industrial infrastructure when we need to be moving away from that mindset. Instead, we are getting the message that consumerism is just fine, as long as we carry it home in cassava bags.

Related: Just one word: Microplastics


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