A freshly opened renewable natural gas (RNG) plant in Story County is converting cornstalks into fuel to heat Iowa homes. 

The converted ethanol plant is owned by Verbio Agriculture, a subsidiary of Germany-based Verbio Group, which bought the facility from DuPont about two years ago. 

It started producing renewable natural gas last December, becoming the first U.S. industrial-scale RNG facility using agricultural residues as feedstock.  

“We’re quite pleased with the outcomes so far,” said Ron DeJongh, president of Verbio Agriculture. “Like any start-up, you run into challenges. But our parent company already has three of these plants operating in Germany, so there is a lot of technical expertise there.”

The RNG plant in Nevada connects with Alliant Energy’s natural gas pipeline. Once fully operational next year, the plant will produce enough RNG to heat about 5,000 homes.

Stover harvest

In 2021, Verbio collected corn stover from 6,500 acres of fields in central Iowa. This year, the company wants to grow that to 35,000 acres, totaling between 75,000 to 100,000 tons of stover, all collected within 50 to 75 miles of the plant.

DeJongh said livestock farmers who grow corn-on-corn found harvesting a portion of overly abundant stover helpful.

“We take the corn residue off, which allows them the opportunity to more easily put hog manure down,” he said. “We also found that by removing half the cornstalk from the field, farmers saw better yields.”

Positive response

As Verbio works to expand stover collection, DeJongh said there will be plenty of opportunities to partner with farmers in the area. 

“We’ve had a very positive response from producers we worked with last year,” he said. “We expect all of them to sign back up.”

Farmers are paid $8 a bale for stover. Verbio takes care of harvest and hauling.

Verbio plans to mail information to farmers in central Iowa with information about corn stover harvest contracting opportunities. The company will also hold community meetings to answer questions from farmers. 

Verbio has hired a team of agronomists to aid in communications and outreach efforts.

By product opportunities

In addition to RNG, the process produces humus, which DeJongh described as a soil conditioner and improver. The byproduct will be sold to farmers in the area who can use it to increase organic matter in their fields.

As the business expands, Verbio plans to reactivate ethanol production at the facility, adding another market for farmers to sell their corn.

“We’re planning to buy about 20 million bushels of corn a year when fully operational,” DeJongh said. “That’s new de­mand to the area.”

He said the dried distillers grains coming from ethanol production will then be rolled back into the RNG process, increasing plant efficiency. 

Some of the RNG produced at the plant runs the facility’s boiler system, which delivers heat needed for the production process. 

“Our aim is to have a low environmental impact,” DeJongh said. 

Farmers or landowners interested in signing up for stover harvest can call the plant directly at 866-306-4777, extension 3003.