Sankey Diagram of Polyethylene Terephthalate (PET) Material Flows in the United States.

[NNadir]

The "Plastic Problem" is a major environmental crisis, among many. We all recycle plastics whenever we can, but the question is what really happens to the recycled material. A Sankey diagram of the material flows of PET can be found in the following publication: Recycling of Plastics in the United States: Plastic Material Flows and Polyethylene Terephthalate (PET) Recycling Processes Raymond L. Smith, Sudhakar Takkellapati, and Rachelle C. Riegerix ACS Sustainable Chemistry & Engineering 2022 10 (6), 2084-2096.

It's here:



The caption:

Figure 2. U.S. flows of PET in million lb, adapted from NAPCOR. (31) Yellow represents nonbottle “thermoform” PET resin, blue represents collected bottle PET resin, and light red represents uncollected bottles. Green represents rPET converted into products, while dark red represents disposal and mismanaged waste. The gray U.S. reclaimer residue represents unknown stream exiting reclaimer processes.

Some unpleasant reality is obviated here. The units here are unfortunate English units, millions of pounds. A pound is 0.000453592 metric tons. The amount of PET plastic land filled here, 6685 million pounds translates thus into roughly 3 million metric tons. PET is roughly, by weight, 62.5% carbon. This translates into about 1.9 million tons of carbon. To provide carbon for this quantity of material via the appropriate reduction of carbon dioxide would involve, ignoring (as is not really justified) material losses, would involve approximately 6.9 million tons of carbon dioxide. The world dumps about 35 billion tons of carbon dioxide each year from the combustion of dangerous fossil fuels while we all wait increasingly breathlessly for the grand so called "renewable energy" nirvana that did not come, is not here, and won't come. (Another 10 billion tons of carbon dioxide finding its way into the atmosphere is related to land use changes.) This outlines some idea of the scale required to sequester carbon in the form of polymers, something on which I often muse. The carbon dioxide that would be required would represent as a fractional factor 0.0002 of the carbon dumped each year, or in "percent talk" 0.02% of the world's current annual rate of carbon dumping.

It is wise to consider scale, something seldom done when we hear of laboratory "breakthroughs" involving this or that.

Have a nice day tomorrow.