The success of the harvesting corn stover as a biomass hinges on a cost-effective and efficient solution to storing and transporting the stover. In order for producers to become comfortable with the idea of harvesting corn stover, they must have a profitable outcome including all harvest, packaging, transportation, and any other costs. Many studies have been conducted on the feasibility of collecting and transporting corn stover. The logistic models used focus directly on the transportation of the stover from the field to the bio-refinery.
Corn stover is generally harvested between late summer and fall, so the window for collecting the crop is approximately 60 calendar days for Iowa (National Agricultural Statistics Service, 2013). Refineries, however, need a constant supply of stover all year round. Therefore the distribution and size of the biomass storage locations must be considered. In general, most systems include local storage sites within approximately two to nine miles of a field site, with the bio-refineries placed anywhere from about 32 to 97 kilometers away from any given local storage area (Morey et al., 2010). This distance is dependent on the size of the refinery and the geographic location. During storage, the material must be protected to prevent excessive dry matter loss and prevent deterioration in the quality of the material.kilometers away from any given local storage area (Morey et al., 2010). This distance is dependent on the size of the refinery and the geographic location. During storage, the material must be protected to prevent excessive dry matter loss and prevent deterioration in the quality of the material.
In general, transportation of stover bales is the most common logistical method, and in some cases, further pre-processing such as pelletization occurs to increase density. The best economic option is dependent on the size of the bio-refinery. Suh and Suh (2010) present that transportation of pellets by truck, as compared to standard bales (340 kg), can decrease logistical costs for refineries producing 276 million liters per year or more. However, they also simulated the logistical cost model for a larger bale size of 540 kilograms, and found that regardless of the size of the refinery, the large bale transportation option resulted in the least cost, by at least five dollars per dry ton (Suh & Suh, 2010). Sultana and Kumar, (2011) have found baling to be the least expensive option to deliver the stover, due to the higher fixed cost of the production of pellets. Other studies found the total delivery cost of bales to be between about 40 and 50 dollars per dry ton, depending on the size of the bio-refinery (Perlack & Turhollow, 2002). Overall, pelletizing incurs higher equipment costs that would be difficult for individual farmers to employ. With all of this data, the most feasible option in the short term is to produce bales of stover and transport them to the refineries by trucking systems. Even in the long term, this option allows for improvements to the logistic system. In addition, as technology increases, and the densification of the matter becomes more effective, the bale option becomes even more valuable.
Large Module Type Systems:
Recently, some research has been conducted on the use of larger module type packages for collection and transportation of biomass. This research utilizes a modified cotton module builder to create a module of sorghum about 2.4 m by 2.4 m and about 5.5 m long (Searcy, et al., 2014). In order to package these modules, a plastic bag is designed to fit inside the cotton module builder and the material is packed into the machine.
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