Former DuPont ethanol plant is reborn to make renewable methane

In 2017, DuPont closed a cellulose-based ethanol plant in Nevada, Iowa. The chemical maker had spent $200 million on a fermentation process that turned corn cobs, stalks, and leaves into the fuel, but it couldn’t make the economics work.

Now the facility is getting a new life. The German company Verbio bought the site from DuPont in 2018 and earlier this month inaugurated a new plant on the property that is the first in the US to make natural gas from cellulose.

Verbio says it spent $50 million installing huge anaerobic fermenters that can convert 100,000 metric tons per year of corn leavings into a renewable natural gas. Alliant Energy is distributing it via pipeline to customers in Iowa.

Greg Northrup, CEO of Verbio in North America, says the next step will be to convert the cellulosic ethanol facility into a conventional corn-based ethanol plant. Distillers grains, a by-product from that operation, will be an additional raw material for renewable natural gas. And the humus that remains after gas production can be returned to corn fields as a fertilizer.

The US is home to some 200 corn ethanol facilities that could be retrofitted with Verbio’s system, Northrup says. He sees the technology helping the US get to something like its 2022 target of making 16 billion gal (60 billion L) of advanced biofuels like cellulosic ethanol and natural gas. To date, the country has produced less than 1 billion gal, he says.

“I felt really bad for DuPont,” Northrup says, “because they were trying to do new things, and after 12 years it didn’t work for them.” He says cellulosic natural gas will be an advanced biofuel that does work.