Corncobs and sugar are the primary ingredients in a new process to produce plant-based plastics
Scientists from the University of Wisconsin are reporting progress on getting more sugar into soda bottles. While this may sound like they’re aiming to compete with Jolt or Mountain Dew, they’re actually investigating the bottles themselves, or more specifically, the plastic they’re made of. Plastic bottles, food packages and polyester fabric all use polyethylene terephthalate (PET), which is produced from petroleum, and thus requires a huge amount of carbon emissions in their production. If costs can be managed, some of that plastic production may be replaced with a material made from sugar and corncobs, reducing the amount of oil needed for the million plastic bottles used every minute in the United States alone.
The sugar-based product is polyethylene furandicarboxylate (PEF), a plastic doesn’t require any oil to produce while at the same time doing a better job at preserving foods than PET. The key to its production is furandicarboxylic acid (FDCA), which has been available for years, but generally considered too expensive to make PEF practical. Fortunately, corncobs have turned out to be a good source for a solvent that can lower the manufacturing costs of FDCA while also reducing the amount of sugar needed in the first place. If that weren’t enough, this process removes the need for expensive reactors to handle other acids associated with PET production, while also allowing some of the corncob-solvent to be recycled for the next round of production.
A catch with the costs
This may seem like an obvious win, but unless we’re willing to pay more for our bottles and packages, it’s not clear that it will be cheaper than PET yet. A metric ton of PEF made from sugar and corn would be around $45 more than the same amount of PET, although researchers are hoping to shave $200 off that price after they optimize the system. They’re also competing with other sugar-based processes that don’t require the use of platinum, a metal rare and expensive enough to offset some of the gains from making use of all those corncobs.
The final concern is that this process may end up being too good, and then backfiring. If costs can be brought down, the demand for plastic is so high that sugar and corn prices might get pushed up. We’d then be left with the weird trade-off of a carbon neutral, or potentially carbon-negative, product that’s so cheap it makes the sugary beverages it contains more expensive. Then again, we shouldn’t be using this much plastic in the first place, so anything to reduce their impact on the planet is probably worth it in the long run.
Source: Here's a sweet recipe for cheap, green plastic—sugar and corncobs by Roni Dengler, Science