Recently, Greta Thunberg has strongly increased environmental awareness with the climate strikes and the resulting Fridays for Future movement. But what does environmentally friendly behavior look like? In today’s society, it is a sort of common sense that one should recycle. From an early age, we are taught in school that recycling conserves resources and energy. However, there are also skeptics of this “common sense.” In 2004, for example, Penn and Teller dedicated an episode of their TV show to recycling. According to them, “[Recycling] increases energy use in transport, sorting, storing, and cleaning …. it takes more energy to recycle a plastic bottle than to make a new one, and that’s not so good …. we’re feeling good for no reason.” We hope that when people start to question the validity of recycling that they will turn to their physical science teachers for help, and we hope that these teachers will be able to give an informed and educated answer. In this article, our goal is to provide physical science teachers with the information they need to defend the position that recycling plastic bottles is worthwhile, and to expose the myth that recycling plastic bottles is just “feeling good for no reason.” Although the primary intention of this paper is to supplement content knowledge of physical science teachers regarding sustainability, it will conclude with some instructional suggestions of how students can be guided through debunking on their own the myth that recycling plastic bottles causes more harm than good.

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It is often surprising and disappointing for students to learn that not every item placed with good intention into a recycling bin is actually recycled. This is a reason many laypeople who are critical of recycling use to argue that it doesn’t matter whether you put it in the trash or recycling bin: it goes to the same place in the end anyway. The fallaciousness in the argument can perhaps more clearly be explained by focusing on the 90% of the plastic that is recycled. In the analysis we are presenting in what follows, we consider the energy needed to produce a bottle from recycled material (that is, the material comes from the 90% that actually is recycled).
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The variation in energy requirements is the result of diverse methods utilized in the respective processes. Readers interested in learning more about these processes will find details in the articles cited.
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Note that many “recycled” bottles in Austria are 25% recyclate. In this case, the energy cost for producing pellets would of course be 75% the amount needed if from entirely virgin resources. This is another point that may disdain students about recycling. Similar to what was mentioned in the previous footnote, we are considering bottles that are actually made from recycled bottles (as in, 100% recyclate) for our comparison.
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