Is creating plastics from biomass really a ‘green’ idea?: Page 2 of 3

It seems we have a real circular plastics manufacturing process here. We grow plants, grasses and crops to harvest, transport and process into plastic, which releases a lot of “waste CO2” into the atmosphere. We then have to capture that waste CO2 and turn it into plastic while at the same time scientists are turning the biomass into bioplastics. Perhaps if we didn’t harvest all of those grasses, crops and other biomass products to make bioplastic, we’d have less CO2 in the atmosphere. Would making plastic from waste CO2 be any greener than making it from natural gas or natural petroleum? That is a question I’ll be asking this week when I interview some scientists working on carbon upcycling technology.

David Nield, author of the ScienceAlert article, notes that the new approach “is the most efficient method yet that scientists have devised for converting carbon dioxide into ethylene, the raw material used to make the most commonly used plastic, polyethylene. And it brings the possibility of a practical CO2-to-plastic conversion system a whole lot closer.” (Maybe closer, but greener? That remains to be seen.)

A new piece of equipment developed by Tom Regier, Senior Scientist at the Canadian Light Source (CLS) facility at the University of Saskatchewan, allowed the team in Nield’s article to analyze matter with electromagnetic radiation to identify the key catalyst. “This has never been done before,” said Rafael Quntero-Bermudez from the University of Toronto, who was part of the team.

“The catalyst is necessary to power a carbon dioxide reduction reaction, converting CO2 into other chemicals when it gets hit with an electrical current. While many metals can act as catalysts, we already know that copper is the only one that can produce ethylene,” said Nield’s article.

“Copper is a bit of magic metal,” said Phil De Luna of the University of Toronto in Nield’s article. “It’s magic because it can make many different chemicals, like methane, ethylene and ethanol, but controlling what it makes is difficult.”  

“Armed with this new knowledge and a suitable carbon capture technology, we could potentially remove CO2 from the atmosphere while producing plastics in an environmentally friendly way at the same time,” wrote Nield. “As long as the energy required for the conversion can be provided by a renewable source, and the resulting plastics can be reused or recycled later in life, the overall impact should be a positive one.”

The key question here is whether this process can be done without using fossil fuels for the energy required to do the conversion. Another question: If that plastic is made from CO2, do plastic bottles, containers and so forth sequester that CO2? Is that then released back into the atmosphere when the bottles and containers are recycled for reuse?

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