David W. Templeton

Compositional Analysis of Lignocellulosic Feedstocks. 1. Review and Description of Methods

As interest in lignocellulosic biomass feedstocks for conversion into transportation fuels grows, the summative compositional analysis of biomass, or plant-derived material, becomes ever more important. The sulfuric acid hydrolysis of biomass has been used to measure lignin and structural carbohydrate content for more than 100 years. Researchers have applied these methods to measure the lignin and structural carbohydrate contents of woody materials, estimate the nutritional value of animal feed, analyze the dietary fiber content of human food, compare potential biofuels feedstocks, and measure the efficiency of biomass-to-biofuels processes. The purpose of this paper is to review the history and lineage of biomass compositional analysis methods based on a sulfuric acid hydrolysis. These methods have become the de facto procedure for biomass compositional analysis. The paper traces changes to the biomass compositional analysis methods through time to the biomass methods currently used at the National Renewable Energy Laboratory (NREL). The current suite of laboratory analytical procedures (LAPs) offered by NREL is described, including an overview of the procedures and methodologies and some common pitfalls. Suggestions are made for continuing improvement to the suite of analyses.

Compositional Analysis of Lignocellulosic Feedstocks. 2. Method Uncertainties

The most common procedures for characterizing the chemical components of lignocellulosic feedstocks use a two-stage sulfuric acid hydrolysis to fractionate biomass for gravimetric and instrumental analyses. The uncertainty (i.e., dispersion of values from repeated measurement) in the primary data is of general interest to those with technical or financial interests in biomass conversion technology. The composition of a homogenized corn stover feedstock (154 replicate samples in 13 batches, by 7 analysts in 2 laboratories) was measured along with a National Institute of Standards and Technology (NIST) reference sugar cane bagasse, as a control, using this laboratorys suite of laboratory analytical procedures (LAPs). The uncertainty was evaluated by the statistical analysis of these data and is reported as the standard deviation of each component measurement. Censored and uncensored versions of these data sets are reported, as evidence was found for intermittent instrumental and equipment problems. The censored data are believed to represent the “best case” results of these analyses, whereas the uncensored data show how small method changes can strongly affect the uncertainties of these empirical methods. Relative standard deviations (RSD) of 1−3% are reported for glucan, xylan, lignin, extractives, and total component closure with the other minor components showing 4−10% RSD. The standard deviations seen with the corn stover and NIST bagasse materials were similar, which suggests that the uncertainties reported here are due more to the analytical method used than to the specific feedstock type being analyzed.

Rapid biomass analysis: new tools for compositional analysis of corn stover feedstocks and process intermediates from ethanol production.

New, rapid, and inexpensive methods that monitor the chemical composition of corn stover and corn stover-derived samples are a key element to enabling the commercialization of processes that convert stover to fuels and chemicals. These new techniques combine near infrared (NIR) spectroscopy and projection to latent structures (PLS) multivariate analysis to allow the compositional analysis of hundreds of samples in 1 d at a cost of about

Simultaneous saccharification and cofermentation of dilute-acid pretreated yellow poplar hardwood to ethanol using xylose-fermenting Zymomonas mobilis.

10 each. The new NIR/PLS rapid analysis methods can also be used to support a variety of research projects that would have been too costly to pursue by traditional methods.

Separation and quantification of microalgal carbohydrates

Simultaneous saccharification and cofermentation (SSCF) was carried out at approximately 15% total solids using conditioned dilute-acid pretreated yellow poplar feedstock, an adapted variant of National Renewable Energy Laboratory (NREL) xylose-fermenting Zymomonas mobilis and either commercial or NREL-produced cellulase enzyme preparations. In 7 d, at a cellulase loading of 12 filter paper units pergram cellulose (FPU/g), the integrated system produced more than 3% w/v ethanol and achieved 54% conversion of all potentially available biomass sugars (total sugars) entering SSCF. A control SSCF employing Sigmacell cellulose and a commercial cellulase at an enzyme loading of 14 FPU/gachieved 65% conversion of total sugars to ethanol.

Rapid Biomass Analysis

Structural carbohydrates can constitute a large fraction of the dry weight of algal biomass and thus accurate identification and quantification is important for summative mass closure. Two limitations to the accurate characterization of microalgal carbohydrates are the lack of a robust analytical procedure to hydrolyze polymeric carbohydrates to their respective monomers and the subsequent identification and quantification of those monosaccharides. We address the second limitation, chromatographic separation of monosaccharides, here by identifying optimum conditions for the resolution of a synthetic mixture of 13 microalgae-specific monosaccharides, comprised of 8 neutral, 2 amino sugars, 2 uronic acids and 1 alditol (myo-inositol as an internal standard). The synthetic 13-carbohydrate mix showed incomplete resolution across 11 traditional high performance liquid chromatography (HPLC) methods, but showed improved resolution and accurate quantification using anion exchange chromatography (HPAEC) as well as alditol acetate derivatization followed by gas chromatography (for the neutral- and amino-sugars only). We demonstrate the application of monosaccharide quantification using optimized chromatography conditions after sulfuric acid analytical hydrolysis for three model algae strains and compare the quantification and complexity of monosaccharides in analytical hydrolysates relative to a typical terrestrial feedstock, sugarcane bagasse.

Development of algae biorefinery concepts for biofuels and bioproducts; a perspective on process-compatible products and their impact on cost-reduction

New, rapid, and inexpensive methods that monitor the chemical composition of corn stover and corn stover-derived samples are a key element to enabling the commercialization of processes that convert stover to fuels and chemicals. These new techniques combine near infrared (NIR) spectroscopy and projection to latent structures (PLS) multivariate analysis to allow the compositional analysis of hundreds of samples in 1 d at a cost of about

Effect of corn stover compositional variability on minimum ethanol selling price (MESP).

10 each. The new NIR/PLS rapid analysis methods can also be used to support a variety of research projects that would have been too costly to pursue by traditional methods.

Enzyme Production, Growth, and Adaptation of T. reesei Strains QM9414, L-27, RL-P37, and Rut C-30 to Conditioned Yellow Poplar Sawdust Hydrolysate

Identifying and addressing critical improvements in biomass, bioproduct and biofuel productivity is a priority for the nascent algae-based bioeconomy. Economic and sustainability principles should guide these developing improvements and help to unravel the contentious water–food–energy–environment nexus that algae inhabit. Understanding the biochemistry of the storage carbon metabolism of algae to produce biofuels and bioproducts can bring to light the key barriers that currently limit the overall carbon efficiency and the photosynthetic efficiency, and ultimately guide productivity and commercial viability in the context of limiting resources. In the analysis reported here, we present different potential pathways for a conceptual algae biorefinery framework, with each pathway addressing one of the main identified barriers to future deployment. We highlight the molecular identification, in the form of an extensive literature review, of potential bioproducts that may be derived directly from both biomass and fractions produced through a conversion pathway, for three important commercially-relevant genera of algae, Scenedesmus, Chlorella and Nannochloropsis. We establish a relationship between each of the potential bioproducts, describe relevant conversion and extraction processes, and discuss market opportunities with values and sizes as they relate to commercial development of the products.

Enzyme production, growth, and adaptation of T. reesei strains QM9414, L-27, RL-P37, and Rut C-30 to conditioned yellow poplar sawdust hydrolysate : Scientific note

A techno-economic sensitivity analysis was performed using a National Renewable Energy Laboratory (NREL) 2011 biochemical conversion design model varying feedstock compositions. A total of 496 feedstock near infrared (NIR) compositions from 47 locations in eight US Corn Belt states were used as the inputs to calculate minimum ethanol selling price (MESP), ethanol yield (gallons per dry ton biomass feedstock), ethanol annual production, as well as total installed project cost for each composition. From this study, the calculated MESP is