Location: Agroecosystem Management ResearchTitle: Cob biomass supply for combined heat and power and biofuel in the north central USA Author
Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2014
Publication Date: 4/17/2014
Publication URL: http://handle.nal.usda.gov/10113/58838
Citation: Schmer, M.R., Dose, H.L. 2014. Cob biomass supply for combined heat and power and biofuel in the north central USA. Biomass and Bioenergy. 64:321-328. Available: http://dx.doi.org/10.1016/j.biombioe.2014.03.051. Interpretive Summary: Corn cobs could be used to power existing corn grain ethanol plants or be converted into a biofuel. We evaluated the use of corn cobs for power production and biofuel potential in the states of South Dakota, North Dakota, and Minnesota. Significant amounts of corn cobs could be sustainably harvested and used for power generation and biofuel production but overall amounts will be dependent on farmer utilization rates. Cob supplies will likely increase in the future with an increase in corn grain yields. We demonstrate that co-locating a cellulosic ethanol plant with an existing dry mill corn grain plant using cobs for power generation significantly reduces net greenhouse gas emissions. Corn grain ethanol plant requirements for cob supply may be constrained in the future because of competition between multiple users. A multi-feedstock approach will likely be required to meet multiple end user renewable energy requirements for the north central United States.
Technical Abstract: Corn (Zea mays L) cobs are being evaluated as a potential bioenergy feedstock for combined heat and power generation (CHP) and conversion into a biofuel. The objective of this study was to determine corn cob availability in north central United States (Minnesota, North Dakota, and South Dakota) using existing corn grain ethanol plants as a proxy for possible future co-located cellulosic ethanol plants. Cob production estimates averaged 6.04 Tg and 8.87 Tg using a 40 km radius area and 80 km radius area, respectively, from existing corn grain ethanol plants. The use of CHP from cobs reduces overall GHG emissions by 60% to 65% from existing dry mill ethanol plants. An integrated biorefinery further reduces corn grain ethanol GHG emissions with estimated ranges from 13.9 g carbon dioxide equivalents per MJ of ethanol to 17.4 g carbon dioxide equivalents per MJ of ethanol. Significant radius area overlap (53% overlap for 40 km radius and 86% overlap for 80 km radius) exists for cob availability between current corn grain ethanol plants in this region suggesting possible cob supply constraints for a mature biofuel industry. A multi-feedstock approach will likely be required to meet multiple end user renewable energy requirements for the north central United States. Economic and feedstock logistics models need to account for possible supply constraints under a mature biofuel industry.