Biorefineries can convert lignocellulosic plant materials, which include wood, switchgrass and other native prairie grasses, into alternative sources of fuels and other chemicals.

When these materials are used to produce ethanol or other biofuels, a liquid residue called stillage remains. That stillage contains organic materials that can be used to make valuable byproducts, according to an info sheet from the Wisconsin Alumni Research Foundation.

In ethanol plants and other sites where lignocellulosic plant materials are processed, the residue is usually used to produce biogas, the info sheet shows. That biogas is combusted through a process that both powers the facility and creates excess electricity that can be sold. Biogas can also be converted into natural gas and used elsewhere.

Rather than using the stillage residue for biogas alone, researchers have detailed a method for turning some of that residue into more valuable materials.

Led by Daniel Noguera and Tim Donohue, two professors at UW-Madison, researchers found a way to convert leftover byproducts from the residue into a form that could be used to create other products, such as pharmaceuticals, dyes and rubbers.

According to WARF, the new method can create a product stream that’s “approximately 10 times more valuable” than current methods, and could reduce the minimum selling price of ethanol by 18 percent.

The info sheet shows part of the “stillage stream” would lead separately to a bioreactor that contains a specific mixture of microbes, which can turn part of that stillage into the useful byproduct chemicals. The rest of the stream would proceed through the biogas process.

Read the full release here. 

See an earlier story featuring Donohue at a recent Wisconsin Technology Council event.