Influence of Airflow on Laboratory Storage of High Moisture Corn Stover

Abstract

Storing high moisture biomass for bioenergy use is a reality in many areas of the country where wet harvest conditions and environmental factors prevent dry storage from being feasible. Aerobic storage of high moisture biomass leads to microbial degradation and self-heating, but oxygen limitation can aid in material preservation. To understand the influence of oxygen presence on high moisture biomass (50 %, wet basis), three airflow rates were tested on corn stover stored in laboratory reactors. Temperature, carbon dioxide production, dry matter loss, chemical composition, fungal abundance, pH, and organic acids were used to monitor the effects of airflow on storage conditions. The results of this work indicate that oxygen availability impacts both the duration of self-heating and the severity of dry matter loss. High airflow systems experienced the greatest initial rates of loss but a shortened microbially active period that limited total dry matter loss (19 %). Intermediate airflow had improved preservation in short-term storage compared to high airflow systems but accumulated the greatest dry matter loss over time (up to 27 %) as a result of an extended microbially active period. Low airflow systems displayed the best performance with the lowest rates of loss and total loss (10 %) in storage at 50 days. Total structural sugar levels of the stored material were preserved, although glucan enrichment and xylan loss were documented in the high and intermediate flow conditions. By understanding the role of oxygen availability on biomass storage performance, the requirements for high moisture storage solutions may begin to be experimentally defined.

Compatibility of High-Moisture Storage for Biochemical Conversion of Corn Stover: Storage Performance at Laboratory and Field Scales

“…For both anaerobic storage methods, a pressure of 3.9 kPa was applied to the biomass at five separate 300 s intervals during loading in order to maintain homogeneity between reactors and a final packing density of 73.7 and 76.9 kg/m 3 (db) for the ensiling and modified-Ritter reactors, respectively. Storage reactors were modified from a previous design (Wendt et al, 2014 ; Bonner et al, 2015 ) to maintain anaerobic conditions and equipped with an aluminized gas sampling bag to capture and quantify gas formation during the 110-day storage period. Moisture content and gravimetric DML were calculated based on randomly selected samples, as described previously (Wendt et al, 2014 ).…”

“…Storage reactors were modified from a previous design (Wendt et al, 2014 ; Bonner et al, 2015 ) to maintain anaerobic conditions and equipped with an aluminized gas sampling bag to capture and quantify gas formation during the 110-day storage period. Moisture content and gravimetric DML were calculated based on randomly selected samples, as described previously (Wendt et al, 2014 ).…”

Techno-Economic Assessment of a Chopped Feedstock Logistics Supply Chain for Corn Stover

“…The circular day piles are formed by stackers and recovered with screw reclaimers. Losses of 0.75% are assumed in the day piles due to biological degradation, as measured in previous studies of high-moisture corn stover stored aerobically (Wendt et al, 2014). Receiving and day pile construction design parameters are summarized in Table 4.…”

“…In situations where field drying is not sufficient for meeting the moisture target for baling, the resulting high-moisture bales can suffer dry matter losses ranging from 10 to 30% (Shah et al, 2011;Smith et al, 2013;Wendt et al, 2014). Aerobic microbial degradation by bacteria, yeast, and fungi consumes valuable carbohydrates, leaving behind material enriched in non-fermentable biomass components such as lignin and ash.…”

“…The primary drawback of chopped logistics systems is that the transportation costs increase compared to bale systems, as trucks reach the maximum allowable load weights before volumetric capacity has been reached due presence of water, such that long distance transportation is generally thought to be cost prohibitive. However, chopped, wet logistics systems offer multiple advantages over bale systems primarily due to the fact that they have consistently and successfully demonstrated biomass preservation of >95% over 6-12 months compared to the 10-30% seen in aerobic systems (Smith et al, 2013;Emery and Mosier, 2014;Wendt et al, 2014Wendt et al, , 2018. Wet storage systems also reduce the fire risk relative to dry bales in storage and preprocessing.…”