Title: Evaluation of a high-moisture stabilization strategy for harvested microalgae blended with herbaceous biomass: Part I—Storage performance

Abstract

Algal biomass is becoming increasingly attractive as a feedstock for biofuel production. However, the swing in algal biomass production between summer and winter months poses a challenge for delivering predictable, constant feedstock supply to a conversion facility. Drying is one approach for stabilizing algal biomass produced in excess during high productivity summer months for utilization during low productivity months, yet drying is energy intensive and thus costly. Wet, anaerobic storage, or ensiling, is a low-cost approach that is commonly used to preserve high moisture herbaceous feedstock. The potential for microalgae stabilization without the need for drying was investigated in this study by simulating ensiling, in which oxygen limitation drives anaerobic fermentation of soluble sugars to organic acids, dropping the pH and thereby stabilizing the material. Algal biomass, Scenedesmus obliquus, was blended with corn stover and stored in acidic, anaerobic conditions at 60% moisture (wet basis) to simulate wet storage by means of ensiling. Results demonstrate that algae and corn stover blends were successfully preserved in anaerobic, acidic conditions for 30 days with less than 2% dry matter loss occurring during storage compared to 21% loss in aerobic, non-acidified conditions. Likewise, Scenedesmus obliquus stored alone at 80% moisture (wet basis) inmore » acidified, anaerobic conditions for 30 days, resulted in dry matter losses of 6-14%, compared to 44% loss in neutral pH, anaerobic storage and 37% loss in a neutral pH, aerobically stored condition. Additional experiments were performed at a larger scale in which an algae and corn stover blend was subject to mechanical oxygen exclusion and a Lactobacillus acidophilus inoculum, resulting in 8% loss over 35 days and further indicating that acidic, anaerobic conditions can stabilize microalgae biomass. In summary, the stabilization of harvested algae can be achieved through anaerobic storage, securing a feedstock that is labile yet of high value.« less

Authors:

Wendt, Lynn M. ^[1]; Wahlen, Bradley D. ^[1]; Li, Chenlin ^[1]; Kachurin, Georgiy ^[1]; Ogden, Kimberly L. ^[2]; Murphy, J. Austin ^[1]

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+ Show Author Affiliations

1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
2. Univ. of Arizona, Tucson, AZ (United States)

Publication Date:

Thu Jun 01 00:00:00 EDT 2017

Research Org.:

Idaho National Lab. (INL), Idaho Falls, ID (United States); Univ. of Arizona, Tucson, AZ (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Bioenergy Technologies Office

OSTI Identifier:

1374376

Alternate Identifier(s):

OSTI ID: 1550151; OSTI ID: 1580753

Report Number(s):

INL/JOU-16-37833
Journal ID: ISSN 2211-9264; PII: S2211926416307664

Grant/Contract Number:  

AC07-05ID14517; EE0006269

Resource Type:

Accepted Manuscript

Journal Name:

Algal Research

Additional Journal Information:

Journal Volume: 25; Journal Issue: C; Journal ID: ISSN 2211-9264

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

09 BIOMASS FUELS; algae; blending; corn stover; ensiling; storage; techno-economic analysis