Despite millions of tons of available feedstock, ranging from corn stover to switchgrass and wood waste, only a trickle of cellulosic ethanol is being produced. “Cellulosic fuels’ main hurdle seems to be economic,” says Scientific American in sizing up the second-generation biofuel that has failed to live up to expectations for a cleaner-burning fuel that doesn’t compete with the food and feed sectors.
“Simply put, cellulosic ethanol is more expensive to make than ethanol fermented from cornstarch or from sugarcane, the world’s second-largest source of fuel ethanol,” says the magazine. It’s a new field of work that requires many modifications. At POET’s Project Liberty plant in Iowa, corn stover is thoroughly washed when it comes out of the bale, a step that became necessary when operators discovered the feedstock contained three or four times more sand and gravel than engineers expected. The washing reduces the risk of damage to equipment.
POET says there are advantages to running a cellulosic plant back-to-back with a corn ethanol plant. “The combination … could prove more potent economically, but it fails if the goal is to reduce the amount of ethanol made from corn,” says Scientific American. “Instead of replacing corn ethanol, cellulosic ethanol may simply supplement it.”