A Miscanthus Conditioning and Bale Compression Analysis

Open Access
Fasick, Gregory T
Graduate Program:
Agricultural and Biological Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
December 17, 2014
Committee Members:
  • Jude Liu, Thesis Advisor
  • Douglas Herrick Schaufler, Thesis Advisor
  • Charles David Ray Sr., Thesis Advisor
  • Paul Heinz Heinemann, Thesis Advisor
  • Miscanthus
  • Switchgrass
  • Compression
  • Baling
  • Conditioning
  • Biomass
  • Harvesting
  • Biofuels
Miscanthus can be difficult, expensive and inefficient to harvest and handle because of its stiff stalk, tall height and high yield. In order to decrease the cost and increase the efficiency of harvesting miscanthus, the process of harvesting miscanthus was examined. The goal of this research was to examine conditioning techniques for miscanthus, following mowing and prior to small square baling, in order to evaluate the effect of conditioning on bale density, and both the compressive forces and energy consumption required to compress baled miscanthus. Three conditioning methods were tested with miscanthus. Prior to baling, smooth roll conditioning, crimp conditioning and no conditioning were tested to evaluate their effects and compare crop properties after conditioning. After the miscanthus conditioning tests, the crimp conditioning system and no conditioning were selected to be evaluated further and small square bales of miscanthus were made from both types of conditioning. After making small square bales of miscanthus, the bales were compressed with a small square bale lab scale bale compressor. During the compression process, the forces, energy consumption, peak power, and instantaneous densities were measured and calculated. Switchgrass bales were subjected to the same process for comparison purposes. The crimp conditioning method, when used on miscanthus, produced a wave in the crop along its length and significantly changed the crop properties. When the crimp conditioned crop was compared to the unconditioned crop, during the bale compression process, the average compressive force, peak power, energy and specific energy consumption were all statistically less than the unconditioned crop at a 95 % confidence level. In addition, a longer holding time between the compression and retraction phases statistically decreases the length that miscanthus bales bounced back and relaxed; this related to less stress and strain on the bale twine or wire that held the compressed bale together. Conditioned miscanthus bales behaved statistically similarly to switchgrass while unconditioned bales were statistically more difficult to compress, requiring approximately 60% higher compressive forces and consuming 59% more specific energy than conditioned miscanthus.