Issue 2, 2015

Acid-catalyzed algal biomass pretreatment for integrated lipid and carbohydrate-based biofuels production

Abstract

One of the major challenges associated with algal biofuels production in a biorefinery-type setting is improving biomass utilization in its entirety, increasing the process energetic yields and providing economically viable and scalable co-product concepts. We demonstrate the effectiveness of a novel, integrated technology based on moderate temperatures and low pH to convert the carbohydrates in wet algal biomass to soluble sugars for fermentation, while making lipids more accessible for downstream extraction and leaving a protein-enriched fraction behind. We studied the effect of harvest timing on the conversion yields, using two algal strains; Chlorella and Scenedesmus, generating biomass with distinctive compositional ratios of protein, carbohydrate, and lipids. We found that the late harvest Scenedesmus biomass had the maximum theoretical biofuel potential at 143 gasoline gallon equivalent (GGE) combined fuel yield per dry ton biomass, followed by late harvest Chlorella at 128 GGE per ton. Our experimental data show a clear difference between the two strains, as Scenedesmus was more successfully converted in this process with a demonstrated 97 GGE per ton. Our measurements indicated a release of >90% of the available glucose in the hydrolysate liquors and an extraction and recovery of up to 97% of the fatty acids from wet biomass. Techno-economic analysis for the combined product yields indicates that this process exhibits the potential to improve per-gallon fuel costs by up to 33% compared to a lipids-only process for one strain, Scenedesmus, grown to the mid-point harvest condition.

Graphical abstract: Acid-catalyzed algal biomass pretreatment for integrated lipid and carbohydrate-based biofuels production

Supplementary files

Article information

Article type
Paper
Submitted
20 aug 2014
Accepted
12 nov 2014
First published
12 nov 2014
This article is Open Access
Creative Commons BY license

Green Chem., 2015,17, 1145-1158

Author version available

Acid-catalyzed algal biomass pretreatment for integrated lipid and carbohydrate-based biofuels production

L. M. L. Laurens, N. Nagle, R. Davis, N. Sweeney, S. Van Wychen, A. Lowell and P. T. Pienkos, Green Chem., 2015, 17, 1145 DOI: 10.1039/C4GC01612B

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