Conversion of Invasive Plant Species into Ethanol Prohibitively Expensive

Harvesting invasive plants to convert into ethanol may not be as good of an idea as it sounds, according to University of Illinois researchers who say the process is too expensive to work.

"When the topic of potential invasion by non-native biofuel crops has been raised at conferences I've attended, the ecologists in the room have suggested we use biomass from existing invaders instead," Lauren Quinn, an invasive plant ecologist at the school's Energy Biosciences Institute, said in a statement.

"They'd say, 'we have all of these invasive plants," she explained. "Let's just harvest them instead of planting new ones!' But when I analyzed the idea from a broader perspective, it just didn't add up."

Obstacles include the fact that land managers are constantly trying to eradicate the crop, meaning there would not necessarily be harvests available year after year.

Another issue is the need for specialization, including specially-designed harvesting equipment and the creation of new conversion technologies for the pants, among other things.

"One of the biggest issues is the absence of appropriate biorefineries in any given area," Quinn said. "If there isn't one nearby, growers would have to transport the material long distances, and that's expensive."

And then there is the problem of dealing with the differences in cell wall compositions from plant to plant.

"Most existing or planned biorefineries can process only a single, or at best, a small handful of conventional feedstocks, and are not likely to be flexible enough to handle the variety of material brought in from invasive plant control projects," she said.

Quinn doesn't necessarily argue against the process in the future, having focused her research efforts on present-day technologies.

"One day there might be a pathway toward ethanol conversion of invasive biomass," Quinn said. "But until we do get to that point, there may be possibilities to use invasive plants as alternative sources of energy, like combustion for electricity."

In the meantime, the researcher says invasive populations should be removed, followed by ecological restoration.