Corn might give the plastics industry a makeover
Bioplastics and biochemicals made from the sugar and sometimes protein of corn, soybeans and other crops will likely never replace ethanol as one of corn’s key markets. However, they will be a growing market for corn and other field crops if manufacturers can produce them cheap enough to compete with petroleum-based plastics.
"Ethanol has had a massive impact on the corn market but only a minor impact on the fuel market," says Olly Peoples, co-founder and chief science officer for Metabolix, a bioscience company that produces biochemicals and resins to make bioplastics from crops. By contrast, bioplastics and biochemicals have the potential to make a major impact on the plastic and chemical industries.
The ethanol industry produces 14 billion gallons of biofuel, which is equivalent to about 190 million tons of corn sugar, Peoples says. From that, bioscience companies such as Metabolix could produce 90 million tons of biochemicals, which is a year’s worth of U.S. demand for the equivalent convention of chemicals.
"Compostable plastics make sense only if you have a compostable infrastructure." — Frederic Scheer, founder and CEO of Cereplast
The bioplastics industry is even larger. Bioplastics can be made from PHA (Polyhydroxyalkanoates) and PLA (polylactide) resins. PLA plastics are hard and rigid and won’t degrade unless they are sent to a municipal compost facility where temperature and composting time are controlled. PHA plastics are flexible, marine degradable and compostable.
Recent research could expand the market for these and other bio-based products. "We’ve been testing a plastic that is half PLA and half soy protein," says David Grewell, an Iowa State University researcher. "If put it in the ground, it acts like a fertilizer."
Garden pots are one application for this plastic; the pots can be used to grow the plants. When the plants are ready to be put into the ground, they are removed from the pots, and the pots are placed into the garden near the plants’ roots.
Double Duty. "A few months later, the pot has biodegraded and the plant is fertilized," Grewell says.
The self-fertilization feature of these pots is due to the fact that they are made partially using soy proteins. Corn proteins can also be used to produce these bio-pots, which are not yet commercially available.
"We’ve been studying these pots for several years," Grewell says. "From vegetables to flowers, plants grown in these pots are larger, healthier and nicer looking than plants grown conventionally."
Metabolix technology is also used in a biodegradable soil wrap that looks like a plant pot. "You just stick it in the ground along with the plant," Peoples says. Within a couple of months, these pots have fully degraded. Unlike Grewell’s pots, Metabolix pots are made from corn sugars and are not self-fertilizing, but they are commercially available.
Currently, the ethanol industry produces
- 14 billion gallons of biofuel, which is the equivalent of about
- 190 million tons of corn sugar. From that amount of sugar, bioscience companies could produce
- 90 million tons of biochemicals, enough to fulfill an entire year’s worth of U.S. demand for the equivalent convention of chemicals.
Compared to that of petroleum-based plastics, the bioplastics manufacturing process produces fewer greenhouse-gas emissions. Also, bioplastics don’t contain bisphenol A (BPA), which supposedly can disrupt hormones in humans.
However, PHA bioplastics need to be composted. PLA bioplastics can be industrially composted and sometimes recycled, but recycling and composting remain controversial.
Parts of Europe have a composting infrastructure, and like recycling, the U.S. infrastructure is not uniform. Areas with composting include parts of the West Coast, such as Seattle and San Francisco, and states such as Minnesota, Oregon, Pennsylvania and parts of New England.
"Compostable plastics make sense only if you have a compostable infrastructure in place," says Frederic Scheer, founder and CEO of Cereplast, a bioscience company headquartered in El Segundo, Calif. "EPA is pushing for it, but it will take time to build."
- January 2014