Tough decisions would be made much simpler if the answers were always black and white. Unfortunately, managing a biomass supply chain does not always afford the luxuries of clear-cut decision making. We often get asked which feedstock delivery package is best; round bales, square bales, or field chopped material. It is not our intention to dodge this hot topic question by answering with “It depends!”, but the details are always important. Depending on the scale, a commercial ethanol facility can require half-a-million tons of material annually so getting the details right prior to handling this large amount of material is pretty imperative.
Let’s take a very condensed look at some of the pros and cons with each package type to provide some clarity:
Round Bales
The most noteworthy benefit is the weatherability of round bales. A dense, net wrapped bale has shown to be quite effective at shedding water if left out in the rain for a relatively short period. The disadvantages arise from the shape of round bales which provide some inefficiencies during storage and transportation. A pyramid stack of round bales will take up more real estate than a stack of square bales that is equivalent in weight. Additionally, round bales can deform over time when stored in a pyramid stack and round, misshapen bales can be difficult to safely secure on trailers for hauling.
Square Bales
In contrast to round bales, the lack of weatherability is the main drawback of square bales. It doesn’t take much rain to permeate a square bale and quickly degrade the quality of the material. On the other hand, square bales have high densities and stack very efficiently, maximizing the square footage of storage sites and truck trailers.
Field Chop
Forage harvesting material has a distinct advantage in that a level of preprocessing and particle size reduction occurs directly in the field. Also, field chopped material is handled in a bulk, automated fashion. When bale handling is taken out of the equation, a significant reduction in labor requirements is gained. However, the density of field chop material can be 1/3 to ½ of the density of a bale, an obvious disadvantage when accounting for transportation costs.
So obviously there are several variables that come into play when trying to figure out which harvesting package is best. To answer this question, Genera Energy has developed a GIS-based transportation model to optimize the “field chop vs. bale” decision dependent on how far the field is away from the biomass conversion facility. Genera has also completed a DOE grant to research field-side compaction of field chopped switchgrass and effectively achieved 12.5 lb/ft3. Let us know how we can shed some light on, what can be, a hazy question. Contact Genera today to let us evaluate your biomass supply chain plans.
By Lance Stewart, Supply Chain Manager
