Impact of storage and blending of algae and forest product residue on fuel blendstock production

• Published in: Algal research (Amsterdam) 2022-03, Vol.62, p.102622, Article 102622
• Main Authors: Santosa, Daniel M., Wendt, Lynn M., Wahlen, Bradley D., Schmidt, Andrew J., Billing, Justin, Kutnyakov, Igor V., Hallen, Richard T., Thorson, Michael R., Oxford, Tessa L., Anderson, Daniel B.
• Format: Article
• Language: English
• Subjects: 09 BIOMASS FUELS; Algae; algae biofuel, biocrude upgrading, HTL, hydrothermal liquefaction, Silaging, biomass upgrading; Biomass storage; Blended feedstock; Ensiling; Forest product residues; Hydrothermal liquefaction; Hydrotreating
• ISSN: 2211-9264; 2211-9264
• DOI: 10.1016/j.algal.2021.102622

Seasonal impacts on the production of algae biomass require blending with other feedstocks such as wood to maintain consistent annual conversion capacity. Idaho National Laboratory (INL) has developed a long-term storage strategy for algae biomass using ensiling, or anaerobic wet storage, that was tested for blends of algae and wood to stabilize the feedstock supply for processing to fuels. Additionally, blending biomass (algae and wood) leverages existing biomass storage approaches commonly used by the feed and forage industry. Earlier research also has demonstrated positive results that indicate ensiling is more effective and economical in normalizing biomass feedstock supply prior to conversions such as HTL (hydrothermal liquefaction) than preserving biomass by drying. By assessing impacts beginning with upstream logistic operations and proceeding through each conversion step, this work focuses on conversion of ensiled and blended biomass to fungible liquid transportation fuel blendstocks. This is accomplished by conversion of the blended biomass (62% Chlorella sp. blended with 38% loblolly pine forest product residues [FPR]) to bio-crude through HTL and subsequent upgrading through HT (hydrotreating) with a commercial refinery catalyst analogous to a refinery process to produce hydrocarbon fuel. Results indicate that carbon retention and quality are preserved in both the bio-crude and upgraded fuel from the ensiled blend, indicating the potential of this approach for managing seasonal variations in algae biomass productivity. •Storing of blended of biomass may beneficially impact biomass processing and commercial application in refineries by normalizing supply throughout the year.•Storing is a promising preservation method from a life cycle assessment perspective. The wet storage approach to algal biomass stabilization significantly reduces greenhouse gas releases compared to an approach that uses natural-gas-based drying for biomass stabilization.•The HTL-HT (Hydrothermal liquefaction-Hydrotreating) pathway enables evaluation of the suitability of ensiled biomass as a feedstock for HTL conversion to biofuels. The final yields and quality of fuels obtained from ensiled and non-ensiled algae-FPR (Forest product residue) blends through the HTL-HT pathway were similar and differences observed are minor.•Light acids are formed from fermentation and decomposition of hemicellulose in ensiled biomass and is from the aqueous phase during HTL. As a result, bioc