How the US’s Most Abundant Crop Is Changing the Way Plastic Is Produced

Corn is at the heart of the US food system. As the country’s most valuable crop, it generates about $75 billion in revenue every year. It’s also the most widely planted, grown in all 48 contiguous states across about 90 million acres a year — an area roughly the size of Montana. In fact, the US is the largest producer, consumer and exporter of corn in the world.

Of all that corn, however, only 1 percent of it is the sweet variety enjoyed at the dinner table — the other 99 percent is field corn. As opposed to sweet corn, which is a vegetable picked fresh in the summertime, field corn is a grain harvested dry in the fall once the stalks and leaves turn brown and the kernels harden on the cob; it is primarily used for feeding livestock (cattle, hogs and chickens) and making fuel ethanol. The remainder is processed into products such as starch, sweeteners, corn oil and beverages for human consumption.

After the grain is harvested in the fall, farmers are left with what is known as corn stover — the residue of stalks, leaves. It’s usually left on the field and tilled back into soil when it’s ready to be re-seeded. However, with US corn output rising (up a projected 11 percent this year) and grain yield topping 175 bushels per acre, many farmers have more corn stover than they know what to do with.

What if there was a way to help corn farmers deal with their corn stover by transforming it into something valuable?

New Energy Blue has developed a process for turning corn stover into biobased ethylene. The company buys the agricultural residue from farmers, careful to leave the bottom half of the stalks on the field to replenish the soil. The top half is baled as feedstock for converting into ethanol at New Energy Biomass Refinery operations now being developed in the US’s heartland. Almost half of the ethanol produced is then processed into plant-based ethylene — the hydrocarbon gas widely used to produce plastic.

A perfect example of the circular economy in action, the corn stover is no longer waste; instead, it becomes a valuable cash crop for which farmers can get paid.

“There’s too much corn stover left in the field because of the amount of corn being grown — and you need to remove it,” Thomas Corle, CEO and Chairman of New Energy Blue, told Sustainable Brands®. “So, our biomass refinery is a good solution for the farmers. They get an additional revenue stream from corn stover, which is especially welcome given the fluctuating price of corn grain.”

To effectively scale up processing, New Energy Blue has joined forces with Dow — with which it signed a long-term supply agreement in North America in May. Dow will purchase the biobased ethylene and use it in recyclable applications across packaging, transportation and footwear.

“Dow is supporting the first sustainable commercial production using this new technology, because investing in innovation creates the best chance of finding new solutions,” says Manav Lahoti, Dow’s Global Sustainability Director for Olefins, Aromatics & Alternatives. “Dow’s agreement to purchase biobased ethylene enables New Energy Blue to scale its production and ensures a value-added end market for diversion of agricultural residues.”

Corn plants absorb carbon dioxide as they grow; stover releases some of that into the atmosphere as it decomposes on the field after harvest. By reusing the otherwise wasted carbon, New Energy Blue’s innovation is also helping to cut greenhouse gas emissions from the agricultural sector.

The collaboration will enable the design and development of a new processing facility called New Energy Freedom in Mason City, Iowa. When it opens in 2025, it will process 275,000 tons of corn stover every year, delivering commercial-scale quantities of second-generation ethanol and clean lignin —a polymer that makes the cell walls of plants rigid. Around half of the ethanol will be turned into biobased ethylene feedstock for Dow products. It’s the perfect location given that Iowa, along with Illinois, account for around a third of the corn grown in the US.

"Our biomass refinery has the ability to create bio-feedstock that can go into products ranging from textiles and plastics to jet fuel," Corle said. “Thanks to this innovation, Dow is able to use a renewable carbon feedstock to manufacture biobased plastics — which hugely reduces the overall carbon footprint of products.”

This collaboration, Lahoti adds, “will redefine how Dow sources carbon-based feedstocks — allowing us to expand our options for ethylene to include renewable resources. We are excited by the possibility of plastics made from corn stover to help our company achieve our Protect the Climate carbon goal and continue supporting our Transform the Waste recycled-content targets.”

Of the 90 million acres of corn planted in the US annually, only 150,000 acres of corn stover is currently being collected — which means there is opportunity to increase the role of corn stover as a feedstock for biobased plastic or other renewable applications.

And since “biobased ethylene products are chemically identical to fossil-based virgin products, they will be used across a number of different plastic applications throughout our business enabling a lower carbon footprint for a wide range of products,” Lahoti explained. “Potential applications include lightweight materials used for transportation, cosmetics packaging, consumer products like shoes, and food packaging that delivers fresh and reliable products across the country.”

New Energy Blue’s technology not only benefits farmers and businesses — it also ushers in a more sustainable future for US agriculture and exemplifies the power of a circular economy.