Biomass round bales infield aggregation logistics scenarios

Biomass bales often need to be aggregated (collected into groups and transported) to a field-edge stack or a temporary storage before utilization. Several logistics scenarios for aggregation involving equipment and aggregation strategies were modeled and evaluated. Cumulative Euclidean distance criteria evaluated the various aggregation scenarios. Application of a single-bale loader that aggregated bales individually was considered as the “control” scenario with which others were compared. A computer simulation program developed determined bale coordinates in ideal and random layouts that evaluated aggregation scenarios. Simulation results exhibited a “diamond pattern” of bales on ideal layout and a “random pattern” emerged when ≥ 10% variation was introduced. Statistical analysis revealed that the effect of field shape, swath width, biomass yield, and randomness on bale layout did not affect aggregation logistics, while area and number of bales handled had significant effects. Number of bales handled in the direct method significantly influenced the efficiency. Self-loading bale picker with minimum distance path (MDP, 80%) and parallel transport of loader and truck with MDP (78%) were ranked the highest, and single-bale central grouping the lowest (29%) among 19 methods studied. The MDP was found significantly more efficient (4%-16%) than the baler path. Simplistic methods, namely a direct triple-bale loader with MDP (64%-66%), or a loader and truck handling six bales running parallel with MDP (75%-82%) were highly efficient. Great savings on cumulative distances that directly influence time, fuel, and cost were realized when the number of bales handled was increased or additional equipment was utilized

Mass flow and variability in screw feeding of biomass powders – relations to particle and bulk properties

Biomass powders are often cohesive, have low bulk density and poor material flow characteristics which causes interruptions and variations in feeding systems. In this study, a range of biomasses - commercial charcoal, torrefied Norway spruce stem wood, non-treated Norway spruce stem wood, and reed canary grass - was milled (screen size: 1 mm) using two different milling methods; cutting mill and hammer mill, to form eight types of biomass powders. Powders were analyzed for loose density, Hausner ratio, compression ratio, angle of repose and for size and shape distributions. Size and shape were determined by mechanical sieving and optical particle size and shape analysis. Additionally, yield loci and wall yield loci were determined through standard bulk solids testing methods. Screw feeding properties of the eight biomass powders were determined by feeding the materials in a twin screw feeder - at constant rpm and at a constant feeding rate of 1 kg/h. Correlation analysis and principal component loadings were used to describe relations between material properties and feeding characteristics. When materials were fed at a constant rpm, feeding variability was closely correlated to the powders’ angle of repose (long time step) and Hausner and compression ratio (short time step)

A simple viability analysis for unicellular cyanobacteria using a new autofluorescence assay, automated microscopy, and ImageJ

<p>Abstract</p> <p>Background</p> <p>Currently established methods to identify viable and non-viable cells of cyanobacteria are either time-consuming (eg. plating) or preparation-intensive (eg. fluorescent staining). In this paper we present a new and fast viability assay for unicellular cyanobacteria, which uses red chlorophyll fluorescence and an unspecific green autofluorescence for the differentiation of viable and non-viable cells without the need of sample preparation.</p> <p>Results</p> <p>The viability assay for unicellular cyanobacteria using red and green autofluorescence was established and validated for the model organism <it>Synechocystis </it>sp. PCC 6803. Both autofluorescence signals could be observed simultaneously allowing a direct classification of viable and non-viable cells. The results were confirmed by plating/colony count, absorption spectra and chlorophyll measurements. The use of an automated fluorescence microscope and a novel ImageJ based image analysis plugin allow a semi-automated analysis.</p> <p>Conclusions</p> <p>The new method simplifies the process of viability analysis and allows a quick and accurate analysis. Furthermore results indicate that a combination of the new assay with absorption spectra or chlorophyll concentration measurements allows the estimation of the vitality of cells.</p

Effect of Torrefaction on Water Vapor Adsorption Properties and Resistance to Microbial Degradation of Corn Stover

The equilibrium moisture content (EMC) of biomass affects transportation, storage, downstream feedstock processing, and the overall economy of biorenewables production. Torrefaction is a thermochemical process conducted in the temperature regime between 200 and 300 °C under an inert atmosphere that, among other benefits, aims to reduce the innate hydrophilicity and susceptibility to microbial degradation of biomass. The objective of this study was to examine water sorption properties of torrefied corn stover. The EMC of raw corn stover, along with corn stover thermally pretreated at three temperatures, was measured using the static gravimetric method at equilibrium relative humidity (ERH) and temperatures ranging from 10 to 98% and from 10 to 40 °C, respectively. Five isotherms were fitted to the experimental data to obtain the prediction equation that best describes the relationship between the ERH and the EMC of lignocellulosic biomass. Microbial degradation of the samples was tested at 97% ERH and 30 °C. Fiber analyses were conducted on all samples. In general, torrefied biomass showed an EMC lower than that of raw biomass, which implied an increase in hydrophobicity. The modified Oswin model performed best in describing the correlation between ERH and EMC. Corn stover torrefied at 250 and 300 °C had negligible dry matter mass loss due to microbial degradation. Fiber analysis showed a significant decrease in hemicellulose content with the increase in pretreatment temperature, which might be the reason for the hydrophobic nature of the torrefied biomass. The outcomes of this work can be used for torrefaction process optimization, and decision-making regarding raw and torrefied biomass storage and downstream processing

Variations in near‐surface debris temperature through the summer monsoon on Khumbu Glacier, Nepal Himalaya

Debris surface temperature is a function of debris characteristics and energy fluxes at the debris surface. However, spatial and temporal variability in debris surface temperature, and the debris properties that control it, are poorly constrained. Here, near‐surface debris temperature (Ts) is reported for 16 sites across the lower elevations of Khumbu Glacier, Nepal Himalaya, for the 2014 monsoon season. The debris layer at all sites was ≥1 m thick. We confirm the occurrence of temporal and spatial variability in Ts over a 67‐day period and investigate its controls. Ts was found to exhibit marked temporal fluctuations on diurnal, short‐term (1–8 days) and seasonal timescales. Over the study period, two distinct diurnal patterns in Ts were identified that varied in timing, daily amplitude and maximum temperature; days in the latter half of the study period (after Day of Year 176) exhibited a lower diurnal amplitude (mean = 23°C) and reduced maximum temperatures. Days with lower amplitude and minimum Ts were concurrent with periods of increased seasonal variability in on‐glacier air temperature and incoming shortwave radiation, with the increased frequency of these periods attributed to increasing cloud cover as the monsoon progressed. Spatial variability in Ts was manifested in variability of diurnal amplitude and maximum Ts of 7°C to 47°C between sites. Local slope, debris clast size and lithology were identified as the most important drivers of spatial variability in Ts, with inclusion of these three variables in the stepwise general linear models resulting in R2 ≥0.89 for six out of the seven sites. The complexity of surface energy fluxes and their influence on Ts highlight that assuming a simplified relationship between air temperature and debris surface temperature in glacier melt models, and a direct relationship between debris surface temperature and debris thickness for calculating supraglacial debris thickness, should be undertaken with caution

Profile based image analysis for identification of chopped biomass stem nodes and internodes

Because of their significant variation in chemical composition, segregation of chopped biomass into nodes and internodes helps in efficient utilization of these feedstocks. Stem internodes having low ash content are a better feedstock for biofuel and bioenergy applications than nodes. However, separation of these components is challenging because their physical characteristics are similar. We applied an image processing technique to identify nodes and internodes of chopped biomass from scanned digital images. In this study, we utilized the object profile identified differences in the node and internode components and tested on chopped corn stalks and switchgrass stems. We considered four methods of image processing including rectangularity, solidity, width-, and slope-variation and developed an ImageJ plugin for the node-internode identification. Digital chopping of the ends of the objects was necessary for identification, especially dealing with projecting fibers and chipped rough ends, and an algorithm was developed for this. Among the methods tested, width-variation gave the best identification accuracy (97-98%), followed by rectangularity (93-96%), solidity (86-91%), and slope-variation (69-82%). Rectangularity - a relatively simpler method, and solidity - a standard ImageJ output, can be directly used to perform identification. The developed approach of node-internode identification can be easily applied to other chopped biomass and similar materials, and its application may lead to efficient biomass end use in biofuel and bioproduct industries