Could ‘liquid wood’ replace plastic?

But there are tradeoffs. All versions of Arboform are heavier, more brittle, and more expensive than conventional plastics. Arboform costs about $1.60 per pound when purchased in bulk, compared with less than a dollar for a pound of polypropylene, a traditional plastic. Tecnaro produces about 6.6 million pounds of Arboform each year, a capacity that Porter says consistently increases 10 percent each year.

America has a taste for starch
Tecnaro’s products sell in Australia, Brazil, and Colombia, but mostly in Europe, where consumers are more willing to pay for environmentally conscious products – and producers must pay to recycle petroleum-based plastics.

The US mostly backs a different plastic substitute. After giving up on lignin, American scientists focused on starch – a cheap and renewable resource, though one also important to food production.

Cereplast, based in Hawthorne, Calif., harnesses starch from corn, tapioca, wheat, and potatoes to produce a resin capable of replacing at least 50 percent of the petroleum in conventional plastics. Dwarfing upstarts like Tecnaro, the company’s California facility can pump out 50 million pounds of starch-based plastic a year for compostable forks and biodegradeable containers.

But tapping the potential of long-neglected lignin could not only cut the amount of plastic thrown away each year, but could also slow current greenhouse gas emissions. In trees, lignin naturally stores carbon dioxide during photosynthesis, in which plants use sunlight to turn that CO2 into oxygen.

When papermakers discard unwanted lignin, the carbon is still trapped inside it – until they burn the lignin. At that point, much of the CO2 is released into the atmosphere.

“If you can make plastics, or any useful kinds of polymeric materials from lignins … this, of course, would help reduce the rate of global warming quite significantly,” Sarkanen says.

And the question of what to do with lignin instead of burning it is quickly becoming an urgent one. The US Department of Agriculture has mandated that 30 percent of transportation fuels must come from plant materials by 2030.

Producing those “green” fuels involves stripping the lignin from the cellulose in plant matter, an arduous task. Federal funding totaling $375 million over five years now backs three research centers dedicated to efficient biofuel production, one of which is affiliated with Sarkanen’s project to find the enzyme that naturally dissolves lignin without the assistance of a fungus.

“The question of what we’re going to do with lignin besides burning it is coming to the fore,” Sarkanen says. “It’s of enormous potential importance.”

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