WEST SACRAMENTO, CALIF. — Developing a completely plant-based PET requires conquering the elusive, commercially viable bio-based purified terephthalic acid.
Micromidas Inc., a startup based in West Sacramento, Calif., is hoping to reach that goal by swapping typical building blocks of corn or sugar cane for old corrugated cardboard, paper sludge and rice hulls.
To most it's just agricultural waste; for Micromidas, it's feedstock.
"We like the pretty dirty cellulosic streams," joked CEO John Bissell, in a phone interview.
Micromidas uses a chemo-catalytic process to convert cellulosic biomass directly into para-xylene, a precursor to PTA. According to the company, their process is designed to be efficient, selective and high-purity.
Unlike other processes, Micromidas foregoes fermentation. And while most bioplastic typically requires first converting biomass to sugar before continuing the chemical conversion, Micromidas is able to skip that step, Bissell said.
The process also doesn't produce any of the excess co-products of aromatics, like metaxylene or orthoxylene, created when making paraxylene from petroleum, allowing converters to skip an extra purification step.
Using Micromidas' process could allow for bio-based PET on par in price with traditional PET.
The process is designed to be highly efficient and inexpensive. Based on rigorous modeling, it "will be cost-competitive, possibly even advantageous" to petroleum-derived paraxylene, Bissell said.
Using a feedstock like corn would require finding someone to grow and supply the material economically. But Micromidas already knows exactly who to call to get a shipment of old corrugated cardboard and how much it will cost, he said. "We wanted to pull the risk out of something we didn't know anything about."
Using alternative feedstocks has other financial advantages. Farmers, for example, often pay to get rid of agricultural waste like rice hulls. If you can use that material productively as a biomass, "you're ahead of the game," said Ron Schotland, president of Schotland Business Research Inc.
Schotland produces several packaging conferences, including the BioPlastek Forum, set for June 26-28 in San Francisco. Micromidas will present its technology at the forum.
Using agricultural waste also prevents potentially negative impacts on the food supply, Schotland added. "Most people think as soon as you say biomass you mean corn, but … corn is food and the last thing you want to do is create a competition between bio-based chemicals and food."
Micromidas should finish construction on its first pilot plant within the next two months. The plant eventually will consume 1-2 tons of product a day, but it will take some time to get there, Bissell said.
The next step will be a commercial plant, he said.
The company is working with partners "all the way up and down supply chain," from feedstock providers to consumer-product companies, on purity testing, application work and other projects. They're also gathering data on scalability, operations and other considerations.
Micromidas is also starting to have conversations about the future of the technology, Bissell said.
Bissell and his collaborators founded Micromidas in 2008, and their work has its roots in undergraduate research done at the University of California, Davis.
Originally, they were focused on finding ways to generate value out of the waste stream and started work on technology that used fermentation to turn biomass into biodegradable plastics, he said.
In the process, they stumbled on a completely different technology — the current Micromidas technology — that was more interesting and could be brought to scale faster. "It was a complete accident," Bissell said.
Micromidas has been working on its current paraxylene technology since 2010.
The company has around 20 employees. Micromidas said it has raised $25 million in equity capital to date, primarily from Buff Group and Evergreen Capital.
Micromidas isn't the only company looking to conquer bio-PTA.
Chemical engineering researchers at the University of Massachusetts at Amherst announced in May they had discovered a new chemical process to make paraxylene at 90 percent yield from lingocellulosic biomass, the highest yield to date, according to a news release from the university.
The "ultraselective" process "reveals the impact of nano-structured catalyst design on renewable chemical" processes. The group found that a specific material, identified as zeolite beta, was optimal, according to the release.
The discovery is part of a larger effort by UMass Amherst's Catalysis Center for Energy Innovation, which works to create breakthrough technologies for producing biofuels and chemicals from lignocellulosic biomass.