A new study by the US Department of Agriculture (USDA) Agricultural Research Service and University of Nebraska-Lincoln has determined that the farm cost of producing switchgrass for cellulosic ethanol averages $65.86 per metric tonne (Mg) of biomass dry matter, with an annualized yield of 5.0 tonnes per hectare. The study will be published in this month’s BioEnergy Research.
The study contracted 10 farmers in Nebraska, North Dakota and South Dakota to commercially grow switchgrass for five years, starting in 2000 and 2001. Results showed a wide range of yields and costs across the five production years and ten sites, with an overall average cost of $65.86 Mg-1 of biomass dry matter, and annualized yield of 5.0 Mg ha-1.
The low-cost half of the producers were able to produce at an average cost of $51.95 Mg-1 over the 5-year period. When projected to a full 10-year rotation, their cost fell further to $46.26 Mg-1. The researchers concluded that substantial quantities of biomass feedstock could have been produced in this region at a cost of about $50 Mg-1 at the farm gate, which translates to about $0.13 per liter ($0.49 per gallon US) of ethanol. These results provide a more reliable benchmark for current commercial production costs as compared to other estimates, which range from $25 to $100 Mg-1, according to the researchers.
The same team of researchers published a paper in January in the Proceedings of the National Academy of Sciences that found that switchgrass produces 540% more renewable energy as a biomass energy crop for cellulosic ethanol than energy consumed in its production. Previous estimates, based on small scale research plots (<5m2 and estimated inputs) suggested switchgrass would yield a net energy production of about 343%. (Earlier post.)
Richard Perrin, Kenneth Vogel, Marty Schmer and Rob Mitchell, Farm-Scale Production Cost of Switchgrass for Biomass, Bioenerg. Res. DOI: 10.1007/s12155-008-9005-y