Experimental methods for laboratory-scale ensilage of lignocellulosic biomass

Significance Statement

    In the wake of a couple of fires in the biomass storage facilities of POET and DuPont’s Lignocellulosic Ethanol Demonstration Biorefineries, we wanted to bring an article on wet storage of biomass. Tanjore et al. (2012), published in the journal Biomass and Bioenergy, focused on developing experimental methods required to establish ensilage as a storage method for lignocellulosic biomass. Lignocellulosic biomass, such as corn stover, is a sugar-rich source for biofuel production. However, biomass is usually dried on field, harvested, baled, transported, and stored year-long dry near the biorefineries. This leads to risk of fire that, if not contained immediately, can be catastrophic. Biomass can be harvested with high moisture content and stored immediately. Wet storage methods can avoid fires but can lead to significant degradation of the sugars in the biomass due to microbial activity. Ensilage, an anaerobic wet storage system, not only inhibits the growth of aerobic organisms, but also reduces the pH of the biomass to less than 4.0. The pH reduction is obtained by the production of lactic acid by the facultative lactobacillus. The low pH and anaerobic system allows for the wet storage of biomass without sugar degradation. While a number of papers have been published studying this aspect, the methods employed in each of these studies vary significantly. Tanjore et al. (2012) establishes the methods required to study ensilage in a lab-scale setting for wet storage of biomass for biofuel production.    

 

Figure Legend:  Ensilage as a biomass storage method

 Experimental methods for laboratory-scale ensilage of lignocellulosic biomass

Journal Reference

Biomass and Bioenergy, Volume 47, December 2012, Pages 125-133.

Deepti Tanjore, Tom L. Richard, Megan N. Marshall

Pennsylvania State University, Department of Agricultural and Biological Engineering, 249 Agricultural Engineering Building, University Park, PA 16802, USA.

 

Abstract

 

Anaerobic fermentation is a potential storage method for lignocellulosic biomass in biofuel production processes. Since biomass is seasonally harvested, stocks are often dried or frozen at laboratory scale prior to fermentation experiments. Such treatments prior to fermentation studies cause irreversible changes in the plant cells, influencing the initial state of biomass and thereby the progression of the fermentation processes itself. This study investigated the effects of drying, refrigeration, and freezing relative to freshly harvested corn stover in lab-scale ensilage studies. Particle sizes, as well as post-ensilage drying temperatures for compositional analysis, were tested to identify the appropriate sample processing methods. After 21 days of ensilage the lowest pH value (3.73 ± 0.03), lowest dry matter loss (4.28 ± 0.26 g. 100 g-1DM), and highest water soluble carbohydrate (WSC) concentrations (7.73 ± 0.26 g. 100 g-1DM) were observed in control biomass (stover ensiled within 12 h of harvest without any treatments). WSC concentration was significantly reduced in samples refrigerated for 7 days prior to ensilage (3.86 ± 0.49 g. 100 g−1 DM). However, biomass frozen prior to ensilage produced statistically similar results to the fresh biomass control, especially in treatments with cell wall degrading enzymes. Grinding to decrease particle size reduced the variance amongst replicates for pH values of individual reactors to a minor extent. Drying biomass prior to extraction of WSCs resulted in degradation of the carbohydrates and a reduced estimate of their concentrations. The methods developed in this study can be used to improve ensilage experiments and thereby help in developing ensilage as a storage method for biofuel production.

Go To Journal

 

 

 

Check Also

Bimetallic Cu-Ni catalysts supported on MCM-41 and Ti-MCM-41 porous materials- renewable energy global innovations

Bimetallic Cu-Ni catalysts supported on MCM-41 and Ti-MCM-41 porous materials for hydrodeoxygenation of lignin model compound into transportation fuels