When evaluating the economics of the biomass supply chain and the final dry ton cost of delivered feedstock, transportation costs can make up one of the largest components of the total cost. Careful evaluation and planning is necessary to ensure that this component doesn’t continue to grow beyond what is economically feasible.
At the risk of making a broad sweeping generalization, the challenge of moving biomass as economically as possible boils down to one thing: low bulk densities. Depending on the crop, moisture content, and forage harvester, many of our feedstocks can range from 6 to 7.5 pounds per cubic foot. As you might expect, bales do much better and are capable of achieving 12 to 14 pounds per cubic foot depending on baler and feedstock. Due to the large size and relatively low weights of biomass, transportation is oftentimes restricted to local hauls via trucking. There is only so much material you can cram into (or onto) a 53 foot long, 8 foot wide trailer with a legal height restriction of 13.5 feet so optimizing that rectangular space is important to ensure we maximize our available real estate. The inefficient shape of a round bale inside of a square space adds to the complexities.
Additionally, assuming low densities were not an issue, a truck load cannot exceed the gross axle weight rating which typically means that the truck, trailer, and its contents cannot exceed 80,000 pounds. As an example, a sleeper cab truck pulling a 53 foot long trailer that is fully loaded with square bales of corn stover will weigh between 70,000 to 73,000 pounds. This means that there is a remaining 7,000 to 10,000 pounds of remaining weight that could legally be hauled if the bales had higher densities. There could be additional weight available when a lighter day cab could be used for local hauls and the weight of a sleeper cab is not included. Since our cost of hauling is taking up a large portion of our final feedstock costs, optimizing every single load gets a lot of Genera Energy’s focus.
At Genera, we have conducted a substantial amount of biomass hauling, along with research and economic analysis, to optimize transportation. In partnering with the University of Tennessee, we have completed a Department of Energy grant that evaluated the feasibility of utilizing field-side compaction equipment to maximize the bulk densities of field chopped switchgrass in enclosed reinforced trailers. Through this study we made great strides in d