Harvesting Technologies and Costs for Switchgrass Production

As today’s society searches for renewable energy sources that could be an alternative to fossil fuels, biomass and biofuels provide a promising solution. Switchgrass is one of feedstocks that can be utilized as a renewable energy source. When farming, one of the most important considerations is efficiency. This consists of several factors, including time, fuel use, economic and power efficiencies of equipment. Inefficient field operations could increase harvesting costs and in turn could cause hesitation when a farmer decides to participate in biomass production. This literature review will cover the main elements of biomass and biomass handling relating to determining harvesting efficiency and biomass quality for switchgrass round bales. Specifically, the following sections include past research activities relating to biomass harvesting, biomass bale quality during outdoor storage, logistics models, and data collection methods during biomass harvesting. The objective of this review is to examine status and needs for switchgrass round bale harvesting operations and the expenses that come with it.

The Effect of Mechanical Conditioning on Physical Conditions of Miscanthus Plants

Miscanthus is an emerging dedicated energy crop, which can provide excellent yield on marginal lands. However, this crop is more difficult to harvest than many conventional energy crops such as corn stover and switchgrass due to its tall and rigid stalks. Crop samples for laboratory studies were collected from the field and the effects of roll spacing, roll speed, and crop input of a mechanical conditioning device on the physical conditions of miscanthus were studied in a lab setting. Test results showed that mechanical conditioning is effective to change the physical conditions of miscanthus to make baling possible or easier. Results also showed that the roll spacing had the most significant impact on the physical conditions of miscanthus, shown by a 115% increase in conditioning over a 0.95 cm (75%) reduction in roll spacing. Increased roll spacing and speed were shown to decrease the amount of torque required to condition the miscanthus.

大方捆压捆及搬运作业效率的实证研究

大方捆压捆是当前一种公认的高效生物质收获系统。通过对一家商业化农场的麦秸压捆、运捆及贮存的全过程进行了研究,建立一个典型的大方捆收获系统(包括1台大方捆压捆机、2台方捆搬运机和3辆方捆运输车),并对影响大方捆生产及搬运流程的各种因素进行量化分析。根据一个工作日的连续观测结果,分析该收获系统的田间作业性能,确定该收获系统中所使用每一台机械的物料作业能力。本研究还对该收获系统的制约因素进行量化分析,进而探讨提高生产效率或降低生产成本的途径。结果显示,经过8h田间操作,1台大方捆压捆机可以完成340个密度为116kg/m3(湿重)的麦秸捆,为该收获系统的最大生产能力。增加1台压捆机或减少其它机械操作员的数量,可以提高该收获系统的作业效率。本研究中所使用的大方捆压捆机的物料作业能力为13t/h。在种植柳枝稷的田地中进行类似的压捆试验,结果显示该压捆机的物料作业能力相同。

Large square baling and bale handling efficiency—A case study

Large square baling is currently recognized as a high efficiency biomass harvesting system. Baling, bale collecting, and storing at a commercial wheat straw farm was studied as a typical large square bale harvesting system. Factors that affect large square bale production and handling logistics were quantified. Field operations of a large square baler, two bale handlers, and three bale trucks were observed in a full day field operation. System performance was analyzed and material capacities of all machines used in this system were determined based on field measurements. System limitations were quantified, and means to increase system efficiency or reduce production costs were discussed. Results showed that 340 wheat straw bales at a density of 116 kg·m-3 (wet matter) were made with a single large square baler during 8 h field operations. The number of bales produced was the system limitation when one baler, two bale handlers and three bale trucks were used. Adding a baler or reduce the number of operators can increase system efficiency. The large square baler used in this study had a material capacity of 13 Mg·h-1. Similar baling trials were conducted in a switchgrass field and results indicated that the baler had the same material capacity.

Effect of Harvesting Time and Moisture Content on Energy Consumption of Compressing Switchgrass

As a dedicated energy crop, switchgrass may be harvested in fall or early spring depending on weather conditions, field capacities of harvesting machines, storage capacities, field management and availability of machine operators. To reduce storage space demand and increase transportation efficiency, harvested switchgrass should be densified. This research was conducted to examine energy consumption of compressing switchgrass collected from various harvesting seasons. Results indicated that the switchgrass harvested in the spring required the maximum energy consumption to process due to its dry and brittle nature. Conversely, the switchgrass harvested in the fall required less energy to compress due to its higher moisture content and associated reduction in resistive forces. For the same moisture content, fall harvested switchgrass would consume less energy to compress compared to spring harvested due to changes in properties of switchgrass over the winter.

Field test and cost analysis of four harvesting options for herbaceous biomass handling

The nature of most biomass materials is a low bulk density as compared to traditional fuel sources.High handling cost could be a limiting factor in utilizing biomass feedstock.Understanding available harvesting machinery systems and associated costs is critical to future implementation.Four popular harvesting machinery systems were studied and costs were analyzed based on field measurements and calculations.These four systems included(1)round baling and round bale handling systems,(2)large square baling and square bale handling systems,(3)forage harvester and trucking systems,and(4)large square baling plus square bale compression systems.Results indicated that a self-loading forage wagon can reduce the cost to harvest a crop but requires more harvest time.Large square bales were found to reduce cost of handling and transport as compared to round bales.Further research is needed to determine storage costs and deterioration loss of the two bale types.Compressed square bales were found to reduce storage,handling and transport costs.Compressed bale machinery has a high initial cost,which currently makes only valuable for hay export.