Purdue Study Concludes Corn Stover Better Economically Than Switchgrass for Indiana Cellulosic Ethanol
Corn stover is a better feedstock economically than switchgrass for cellulosic ethanol produced in Indiana, according to a study by researchers at Purdue University.
Corn stover is plentiful in Indiana because of the state’s large corn acreage and could be harvested less expensively than switchgrass, said Wally Tyner, Purdue agricultural economist and the study’s lead researcher. Also, with high corn prices, corn stover would provide farmers extra profit without planting additional crops, he said. Switchgrass is a primary crop and must be planted separately.
For cellulosic ethanol in Indiana, corn stover is where it’s at. From a cost perspective, corn stover averages $40 per dry ton delivered to the ethanol plant while switchgrass averages $60 per dry ton. That’s a huge early advantage to corn stover. Then there’s the profit. Farmers would receive an average of $80 an acre extra profit for corn stover and $160 an acre average profit for switchgrass.—Wally Tyner
The Purdue study compared the costs and returns of harvesting corn stover to the growing and harvesting of switchgrass for Indiana ethanol production. Tyner and his research assistants also examined the economic and environmental results of replacing some coal with the two types of biomass at electric power plants.
Using a corn stover yield of 4.25 dry tons per acre from a 160-bushel-per-acre corn crop and a switchgrass yield of 5 dry tons an acre, the study found that in the major corn-growing regions of northern and central Indiana, corn stover was the better cellulosic ethanol feedstock.
The economic numbers were better for switchgrass in portions of southern Indiana where soils are less conducive to growing corn, Tyner said.
I think it is likely that in the next few years cellulose-based ethanol is going to become viable. With $6 and higher per bushel corn it is already very close economically. And since the federal Renewable Fuels Standard calls for the production of 36 billion gallons of ethanol by 2022, of which 16 billion gallons have to be cellulose, cellulosic ethanol will advance.—Wally Tyner
Before cellulosic ethanol can take off a number of issues must be resolved, however, Tyner said.
The biggest issue is going to be contracting. With a corn ethanol plant, if there’s not enough corn in one county you go to another county to get your corn, or get it from out of state. Corn moves cheaply and easily. Biomass, on the other hand, doesn’t. Cellulosic ethanol plants will need a local supply of corn stover and switchgrass. An investor isn’t going to sink $400 million into a cellulosic ethanol plant until they have a local supply of raw material locked up.
Conversely, farmers are going to need assurances that no matter what happens in the marketplace—fertilizer prices triple, natural gas and propane prices do this, diesel prices do that, corn prices go up or down—that growing biomass is viable for them. So we still need to develop risk-sharing, long-term contracting mechanisms that will be acceptable to both the supplier and the ethanol producer.—Wally Tyner