Quantifying Total and Sustainable Agricultural Biomass Resources in South Dakota – A Preliminary Assessment

Conversion of biomass is considered the next major advance in biorenewable fuels, energy, and products.  Wholesale conversion to biomass utilization could result in removal of current crop residues from agricultural fields (on prime agricultural lands) or even implementation of different crops and cropping strategies (i.e., switchgrass on marginal lands).  To date, the driver for biomass processing has been economics and limitations on the conversion of the lignocellulose.  Over the last forty years significant investments and resultant changes in management practices in the agricultural sector have focused on soil and water conservation.  One of the major efforts has focused on conservation-till or no-till, with the goal of retaining biomass residues in the field on the surface to prevent erosion, improve soil structure, and increase biological diversity.  Environmental implications of significant changes to current cropping systems have not been thoroughly addressed, however.  This paper will focus on using South Dakota as a case study to determine the potential for biomass and discuss the implications thereof for the utilization of these materials.  We will consider optimizing the amount of biomass that can be harvested with and without consideration of a minimum level of crop residue left in the field.  Meeting our nation’s transportation fuel needs can be accomplished sustainably, but these issues need to be addressed now, at the outset of this revolution

Ethanol processing co-products: Economics, impacts, sustainability

The US corn-based fuel-ethanol industry is experiencing unprecedented growth. This industry has continually evolved and technological innovations and process changes have been implemented that have improved process efficiencies, but have also affected the resulting co-product streams. As a consequence, new questions, challenges, and opportunities for utilizing these residues have arisen. As the quantity of these materials continues to grow, it is vital that value-added uses for distillers grains continue to be developed

Processibility of corn protein blends and resulting properties of the extrudates

During the last decade, the global biofuels industry has experienced exponential growth. By-products such as high protein corn gluten meal (CGM) and high fibre distillers dried grains with solubles (DDGS) have grown in parallel. CGM has been shown to be suitable as a biopolymer; the high fibre content of DDGS reduces its effectiveness, although it is considerably cheaper. In this study, the processing behaviour of CGM and DDGS blends were evaluated and resulting extrudate properties were determined. Prior to processing, urea was used as a denaturant. DDGS:CGM ratios of 0, 33, 50, 66 and 100% were processed in a single screw extruder, which solely used dissipative heating, with a 2 mm circular die. Resulting screw speeds ranged from 216 to 228 rpm, and die exit temperatures ranged from 96 to 150oC. Blends containing DDGS were less uniformly consolidated and resulted in more dissipative heating. Blends showed multiple glass transitions, which is characteristic of mechanically compatible blends. Transmission electron microscopy revealed phase separation on a micro-scale, although distinct CGM or DDGS phases could not be identified. On a macro-scale, optical microscopy suggested that CGM-rich blends were better consolidated, supported by visual observations of a more continuous extrudate formed during extrusion. As with all biological materials, the extruded blends exhibited sorption behaviour over time, the magnitude of which varied according to blend ratio. EMC values ranged from approximately 0% to nearly 50%, depending upon the humidity level and blend ratio. Nonlinear regression was successfully used to model the effects of relative humidity and blend ratio on the equilibrium moisture contents, with a coefficient of determination of 99%. Future work should aim to also characterize the mechanical properties of these blends to assess their suitability as either bioplastic feedstock or pelletized livestock feed

Single screw extruder performance characteristics during processing of corn protein blends

During the last decade, the global biofuels industry has experienced exponential growth. By-products such as distillers dried grains with solubles (DDGS) have grown in parallel. DDGS is primarily an animal feed, but it has also been shown to be suitable as a biopolymer. In this study, the extrusion processing behaviour of DDGS was evaluated. Prior to processing, water was added to DDGS at a level of 3 kg DDGS to 1.5 kg water (water at 50 parts per hundred (pph)). Additionally, a DDGS/water blend with 50 pph CaCO₃ was used as a tracer to determine residence time during processing. The blends were processed in a single screw autogenous extruder, which relied solely upon friction for dissipative heating. Two die plates were used: one consisted of 6 orifices equally spaced, 2 mm diameter each, with a total opening area of 18.85 mm²; the other consisted of multiple orifices (960 in total) arranged concentrically around the plate, with a diameter of 2.30 mm each, for a total opening area of 3988.45 mm². Processing began with DDGS blends without tracer; after reaching steady state, the tracer blend was introduced. Samples were collected every 5 sec during processing to determine extrudate changes over time. Extruder power consumption, mass flow rate, and temperature profile were determined during processing. Extrudates were analysed for Hunter colour (L-a-b) changes over time. Extrusion processing characteristics were highly influenced by the die opening area. Die exit temperatures ranged from room temperature (25°C) to more than 100°C, purely due to increased friction for the smaller die opening. Future work should characterize the mechanical properties of these extrudates to assess their suitability as either bioplastic feedstocks or pelletized animal feeds