Corn stover converted into bioproducts at research farm

Ben Theobald

At the Biorenewable Research Farm, many projects are underway that deal with conversion or transportation of biofuels.

One project deals with using corn stover transported from fields and harvesting, and converting it into types of bioproducts.

The project is led by Matthew Darr, assistant professor of agriculture and biosystems engineering, and Stuart Birrel, associate professor of agriculture and biosystems engineering.

“Corn stover is all the material left behind after the harvesting of the grain,” Birrel said. “Some of that material needs to be left on the field, because of environmental concerns of making sure we protect the soil. There is a certain portion we can take off the field and utilize for bioenergy or bioproducts.”

Birrel has concentrated more on some of the machinery and sustainability aspects of the project. He also looks at the difficulty, as well as the cost associated with transporting the corn stover from the fields, which is expensive.

“We have a limited distance to move this material,” said Robert C. Brown, director of the bioeconomy institute. “Fifteen miles is as far as you can move it economically.”

There has been a lot of work done on the conversion of the material and economic means of transporting it.

“There has been a lot of work going on in terms of the conversion of the stover into bioproducts, but not as much work on actually making sure there is a feedstock for those biorefineries and that is what we are trying to solve,” Birrel said. “How do we get the material to the biorefinery in a cost effective manner?” 

The biorefining is the process that takes raw material such as corn stover and converts it into a number of products.

“It could be transportation fuels, chemicals or any type of product that essentially needs a carbon product,” Birrel said.

Another factor playing in the transportation of the corn stover is the period it takes to move it and weather conditions.

“One of the problems we have is corn stover, essentially, is harvested about two months of a year but the refinery needs to run 12 months a year,” Birrel said. “You have to store the material and you have to store it so that you don’t lose too much of the dry matter during storage.”

Darr made an important discovery in the research which is a process called torrefaction. Torrefaction is a process in which high temperatures drying without oxygen reformulate the physical properties of the material.

“We like torrefaction for a number of reasons,” Darr said. “It creates a very stable product, which will reduce our losses during storage and allow us to store the material more cost effectively than with other scenarios.”

Darr hopes that once this process has been instituted, producers will transport renewable material such as the corn stover after harvest allowing it to stabilize before the material starts to decay.

“The farming community is becoming more aware of these developments and is looking for ways to produce, store, and deliver biomass at a large scale while insuring high quality feedstock.”