Swiss Researchers Create Eco-Friendly Plastic From Biofuel Waste

A new method for making biodegradable plastic could mean more free farmland for food

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Call it eco-friendly synergy: Scientists have found a cheaper, greener way to make biodegradable plastic from a common waste product of biodiesel production. (Photo: Bo Cheng / ETH Zurich)

In a breakthrough that may benefit two different eco-friendly technologies, a group of Swiss researchers has discovered a way to make biodegradable plastic from a pesky waste product of biofuel.

The market for PLA, a form of plant-derived, biodegradable plastic that’s already being used in food packaging, is projected to grow from 360,000 tons in 2013, to over 1.2 million tons by 2020. But PLA is derived from plants like corn, sugar and tapioca roots (depending on the region). So making megatons of plant-based plastic might mean setting aside millions of acres of land that could otherwise be used to grow food.

But a group of researchers at the Institute of Chemical and Bioengineering at the university ETH Zürich, led by professors Konrad Hungerbühler and Javier Pérez-Ramírez, have outlined a new process for making PLA using glycerol, a waste byproduct of biofuel production. According to the work, recently published in the journal Energy & Environmental Science, this technique saves energy by using a product that is otherwise commonly disposed of in rivers or fed to livestock (despite concerns over its effects), while also producing 20 percent less carbon dioxide than traditional methods.

Rather than using fermentation to create PLA, as is commonly done, the researchers teamed up with scientists from the university’s Advanced Catalysis Engineering group to create a custom catalyst. Made from a microporous mineral, and developed in large part by Pierre Dapsens, a PhD student working with Pérez-Ramírez, the catalyst's structure specifically promotes the desired chemical process.

Of course, with the rising demand for bioplastic, this method wouldn’t be all that useful if the amount of available waste glycerol couldn’t keep pace. But Cecilia Mondelli, a senior scientist at the Advanced Catalysis Engineering group at ETH Zurich and one of the paper’s coauthors, says that shouldn’t be a problem.

According to Mondelli, biodiesel production is expected to reach nearly 40 million tons by 2020, and that crude glycerol waste will make up roughly 10 percent of that weight. “For the moment,” she says, “all forecasts indicate biodiesel production will increase, and the amount of crude glycerol available will be higher and higher.”

For any industry to take off, profit is, of course, also important. And the team says that, by lowering costs, their method could increase profits of PLA production by as much as 17 times or more. Merten Morales, a PhD student in the Safety and Environmental Technology group and another of the paper’s authors, says beyond profitability, their work provides a framework for those who may want to use this method in a new or existing biorefinery.

“What this scientific publication shows, in general,” says Morales, “is the direction to go for [PLA] production, that there is a way, there is an opportunity.”

He also cautions that the team's method won’t be adopted overnight—at least on a mass scale. He points out that the oil industry took more than 50 years to build massive refineries and that their work is aimed more at showing potential investors that a technology that is green can also be profitable enough to be viable.

Even if the bioplastic market booms thanks to this new method, there will still be a substantial need for petroleum-based plastics for the foreseeable future. PLA (at least in its current form) doesn’t handle high temperatures well. So don’t expect it to show up in your coffee cup or microwavable food container anytime soon.

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