Impacts of Harvesting, Storage, and Milling Methods on Biomass Moisture, Mineral Content, Particle Size, and Feeding Efficiency

As the conversion of pulverized coal utility power plants to 100% biomass combustors gains traction globally, understanding the impacts of harvesting, storage, and fuel preparation on biomass properties on feeding characteristics is essential. This study provides examples of field-to-burner processes and identifies key parameters that ultimately influence the biofuel feeding capability. Fuels analyzed include miscanthus, switchgrass, and corn stover. Two harvesting and two storage methods were evaluated. Single cut and forage harvester methods, and indoor baled and silage bagged storage. Preprocessing configurations included initial size reduction using a paper shredder or bale processor, followed by hammer milling processes. The processing methods were required to produce particles with size distributions below 1000 μm. Measurements obtained included fuel mineral content, particle size distribution, aspect ratio, and deviation from the ideal feed rate. The harvesting method using a forage harvester with silage bagging produced the least added mineral matter (1.26 wt% ash), requires the least additional processing, and produces the best fuel for feeding, but is also the most expensive. In contrast, single-cut, raked, and baled switchgrass and corn stover introduced higher mineral contents of 5.54 wt% and 9.23 wt% ash, respectively. In addition, morphology influenced feeding dynamics; miscanthus produced lower aspect ratio particles (3.21–3.27), exhibiting smoother flow compared to high aspect ratio (5.93–6.45) corn stover. Notably, miscanthus deviated from its ideal feeding rate by less than 9%, while corn stover and switchgrass exceeded 17% and 19%, respectively.