Biodegradable plastic made from renewable resources always sounds better than petroleum-based plastics, right? Well, kind of. We know that most bioplastics aren’t biodegradable in the sense that you can toss it in a compost bin and expect it to quickly disintegrate. Bioplastics still often have to go through an energy-intensive recycling process to get them to fully degrade. So, does this make them equally undesirable? Exactly how do they measure up to conventional plastics?
A new study by researchers at the University of Hawaii, Honolulu aimed to find out, and they discovered a few leg-ups that bioplastics have over conventional plastics during the production phase, primarily that bioplastics emit fewer carbon emissions when manufactured.
The researchers analyzed PHA, which is created by bacteria growing on corn-based sugar. They looked at every aspect of where CO2 could be emitted, from chemicals, fertilizers, fuels, fermentation… everywhere. They found that for each pound of plastic created, only .49 pounds of CO2 was emitted, versus 2-3 pounds of CO2 per pound of conventional plastic.
Another type of bio-plastic, PLA made by NatureWorks, LLC, only produced .27 pounds of CO2 per pound of plastic. This is because the most CO2 intensive parts of the process is the fermentation and electricity use, so the company came up with a better way of producing the plastic, which reduced the emissions further.
Considering that bio-plastics produce so much less CO2 than conventional plastics in the production phase, it seems likely that it would be an over-all better solution, right? Well, it gets complicated, especially when trying to compare apples to apples, and there are dozens of ways to look at the situation. For instance, what is the total carbon emission of petroleum-based plastic from manufacture, to recycle, to new product, versus manufacture to landfill – and how does that compare to the same lifecycle of bioplastic? And what percentage of bioplastic is actually being recycled compared to the percentage of conventional plastic being recycled, and how do those ratios stand up to one another? It gets sticky really quickly when trying to figure out exactly how much of an improvement bioplastic is over conventional plastic and where further improvements need to be made. Researchers are still working on data gathering, especially as new production methods emerge such as actually growing plastic.
But there are some major points that put bioplastics in the lime light. They’re made from renewable resources, and possibly waste products from ethanol production, versus the non-renewable resource of oil. They’re biodegradable in at least some sense, where conventional plastic is not.
But bioplastics still have some major issues that need to be sorted out, such as the energy required to break down the plastics, what happens to them when they end up in landfills rather than recycling plants, the fact that there aren’t many facilities that will accept them for recycling... Yet, with all the research being done and the demand for eco-friendly plastic options, it seems likely that these issues can, and will, be worked out fairly soon, and hopefully petroleum-based plastics will be a thing of our troubled past.
written by Clare Elliott, August 27, 2008
written by Max, January 29, 2009
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