We’re seeing the term “marginal lands” pop up often in biofuels stories these days, as scientists and the industry struggle to come up with plant-based fuels that – unlike corn-grain ethanol – make economic sense and don’t rely on high-quality land and cut into food supplies (or even raise prices).
Now, research out the U.S. suggests there might be a “huge untapped resource to grow mixed species cellulosic biomass, plants grown specifically for fuel production, which could annually produce up to 5.5 billion gallons of ethanol in the Midwest alone.”
If this were true, it would be a big deal.
“The value of marginal land for energy production has been long-speculated and often discounted,” Phil Robertson, co-author and a Michigan State University professor, said in a statement. “This study shows that these lands could make a major contribution to transportation energy needs while providing substantial climate and – if managed properly – conservation benefits.”
The scientists, including some from the Pacific Northwest National Laboratory, said they looked at 10 Midwest states and used 20 years of data to gauge the productivity and greenhouse gas impacts of crops such as corn, poplar, alfalfa and old field vegetation.
The researchers tried to figure out how production of cellulosic biofuels would play out using these inputs. Employing computer modeling, they determined that based on the crop yields, local biorefineries pumping out at least 24 million gallons per year could together provide the 5.5 billion gallons.
Federal law requires that by 2022, the U.S. use 16 billion gallons of cellulosic biofuels produced from wood, grasses, or non-edible plant parts, such as corn stalks and wheat straw; 4 billion gallons of advanced renewable biofuels, other than ethanol derived from cornstarch, that achieve a life-cycle greenhouse gas threshold of at least 50 percent; and 1 billion gallons of biomass-based diesel fuel.
The team said their study, published in Nature, was the first “to show that grasses and other non-woody plants that grow naturally on unmanaged lands are sufficiently productive to make ethanol production worthwhile” – and that with careful management, greater efficiency could be achieved.
“With conservation in mind, these marginal lands can be made productive for bioenergy production and, in so doing, contribute to avoid the conflict between food and fuel production,” said Cesar Izaurralde, PNNL soil scientist and a University of Maryland professor.