Secale cereale L.; ensiling; methane yield; pilot test
The rapid growth of cover crop planting area in the U.S. helps with erosion control, soil health, control of greenhouse gases, and also provides abundant biomass for the production of bioenergy and bioproducts. Given the cover crops’ compositional heterogeneity and variability, a tolerate platform technology such as anaerobic digestion (AD) is preferred but has not been widely used for cover crop biorefining. This study evaluated the biogas and methane yields from six cereal rye (Secale cereale L.) cover crops grown in the Midwest, using both bench- and pilot-scale anaerobic digesters. The effects of two critical factors, the total solids (TS) content and ensiling, on digester performance were also investigated. Methane yields of 174.79–225.23 L/kg-VS were obtained from the bench-scale tests using cereal rye as the mono feedstock. The pilot-scale test with no pH adjustment showed a slightly higher methane yield. Ensiling increased the methane yield by 23.08% at 6% TS, but disturbed AD at 8% TS, and failed AD at 10% and 15% TS. Findings from this study would help farmers and the biorefining industry to determine the baseline performance and revenue of cereal rye AD and to develop strategies for process control and optimization.
This study was funded by the USDA-NIFA NLGCA Capacity Building Grants for Non-Land Grant Colleges of Agriculture Program (Award number: 2020-70001-31279). This material is based upon work that is supported by the U.S. Department of Agriculture, Agriculture and Food Research Initiative Competitive Grant No. 2019-69012-29851.
Yang, Liangcheng; Lamont, Lucas D.; Sedbrook, John C.; Heller, Nicholas J.; and Kopsell, David E., "Anaerobic Digestion of Cereal Rye Cover Crop" (2022). Faculty Publications - Agriculture. 4.
Figure S1: The pilot-scale anaerobic digester. Figure S2: Dry matter distribution of the top, middle, and bottom sections of the six cereal rye. Figure S3: Cereal rye methane yields over time.