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While the production costs and logistical benefits of biomass pelleting have been widely discussed in the literature, the downstream economic and environmental benefits of processing pelleted biomass have been largely neglected. To investigate those benefits, we performed a comparative techno-economic analysis and life cycle assessment of producing ethanol using loose and pelleted forms of biomass. Analyses of a 2000 metric tons (dry)/d biorefinery showed that using pelleted biomass is more economical than using loose or baled biomass. The lowest minimum ethanol selling price (MESP) for pelleted biomass was USD 0.58/gal less than the lowest MESP for loose biomass. Among all processing conditions analyzed, MESP for ethanol produced with pelleted biomass was always lower than when produced with loose biomass. Shorter pretreatment and hydrolysis times, higher pretreatment solids loadings, lower ammonia requirements, and reduced enzyme loadings were the primary factors contributing to lower MESP with pelleted biomass. Similarly, pelleted biomass also demonstrated a 50% lower life cycle greenhouse gas emission compared to loose biomass. Emissions from higher pelleting energy were offset by downstream advantage in lower chemical needs.

Cellulosic biorefineries have attracted interest due to the growing energy security and environmental concerns related to fossil fuel-based energy and chemicals. Using pelleted biomass as a biorefinery feedstock can reduce their processing inputs while improving biomass handling and transportation. However, it is still questionable whether energy and emission savings from feedstock transportation and processing can justify pelletization. A life cycle assessment approach was used to compare energy consumption and greenhouse gas (GHG) emissions from pelleted and non-pelleted corn stover as a biorefinery feedstock. Operations considered were pelleting, transportation, and soaking in aqueous ammonia (SAA) pretreatment. Despite greater GHG emissions (up to 25 times higher than the transportation) generated from the pelleting process, the model showed a significant opportunity to offset and even reduce overall GHG emissions considering the pretreatment process benefits. Our process energy analysis showed that SAA pretreatment of pelleted biomass required significantly lower energy inputs (56%) due to the lower-severity pretreatment’s effectiveness. Higher pretreatment solid loadings are allowed when pelleted biomass is used and this reduces the process chemicals and water requirements by 56% and 49%, respectively. This study demonstrated that the SAA pretreatment of pelleted biomass might be a feasible option as the cellulosic biorefinery feedstock.

Oil recovered from dried distillers grain with solubles (DDGS) can be a high-value product over animal feed to provide an additional profit to ethanol plants currently operating at slim profit margins. Fractionations of DDGS and enzymatic hydrolysis were considered in this study to improve the oil recovery from DDGS. A combination of sieving and then air aspiration was used to separate the original DDGS into three different fractions: light, medium, and heavy. The heavier fraction had up to 24% increased oil content compared to the original DDGS. Commercial enzymes, protease, cellulase, and hemicellulase were tested separately and in combinations at 55 °C for 3 h at 130 rpm to determine their effect on oil recovery from the original and fractionated DDGS. Oil recovery was significantly improved (around 20%) following enzyme hydrolysis of the sieved aspirated heavy fractions of DDGS compared to the original DDGS. More than 90% of oil recovery was achieved by using a combination of cellulase and protease enzymes. Increasing the temperature above 55 °C without any enzyme did not impact oil recovery using the heavy-fraction DDGS. Overall, fractionation and enzymatic hydrolysis showed promise to increase oil recovery from DDGS without any current ethanol plant design changes.

Metallic powder and binder mixing mechanism plays a vital role in the quality of molded parts in metal injection molding. The present study is intended for experimental and theoretical investigation of powder–binder mixing mechanism to investigate the functional correlation among mixing parameters and performance characteristics for different composition of feedstocks. Powder loading and shear rate are considered as input parameter. Fuzzy expert system is adopted to test the validity of the experimental results by analyzing different numerical error criteria using the viscosity as output with respect to input parameters. The mean relative error and correlation coefficient for type A and type B were found to be 6.09% and 8.51% (<10%) and 0.990 and 0.998, respectively. Hence the result indicates a reliable acceptability of the proposed amount of powder loading for feedstock preparation.