Demonstration and Evaluation of Hybrid Microalgae Aqueous Conversion Systems for Biofuel Production

Yalin Li, Shijie Leow, Tao Dong, Nicholas J. Nagle, Eric P. Knoshaug, Lieve M.L. Laurens, Philip T. Pienkos, Jeremy S. Guest, Timothy J. Strathmann

Research output: Contribution to journalArticlepeer-review


As an effort to develop affordable and sustainable energy sources, algae-derived biofuels have attracted considerable interest. As use of individual conversion processes targeting a subset of biochemical components (e.g., extraction and upgrading of lipids) has been shown to be economically unfeasible, there is a recognized need for integrated conversion systems that can valorize algal feedstocks with varying cell compositions. In this study, two hybrid systems (HBD-1, HBD-2) are proposed to enable more efficient conversion of all biomass components (lipids, proteins, carbohydrates) by leveraging two complementary systems: direct hydrothermal liquefaction (DHTL) and combined algal processing (CAP). Demonstrative experiments with Scenedesmus acutus show a 12.2-34.3% increase in fuel yields relative to individual systems (DHTL, CAP). Subsequent modeling efforts reveal substantial improvements stemming from CAP valorization of carbohydrates and lipids and DHTL valorization of proteins and CAP residuals. The maximum biomass-to-fuel conversion efficiencies for lipids/proteins/carbohydrate cell components are 79%/34%/75% (HBD-2), and techno-economic analysis suggests a 3.2-62.1% reduction in minimum fuel selling prices (MFSPs). The increased fuel yields and reduced MFSPs highlight the flexibility of the hybrid systems for biofuel production, revealing advantages of these systems for broader ranges of feedstocks, including ones not traditionally considered for fuel production.

Original languageEnglish (US)
Pages (from-to)5835-5844
Number of pages10
JournalACS Sustainable Chemistry and Engineering
Issue number6
StatePublished - Mar 18 2019


  • Algal biofuel
  • Combined algal processing (CAP)
  • Hydrothermal liquefaction (HTL)
  • Minimum fuel selling price (MFSP)
  • Techno-economic analysis (TEA)
  • Valorization

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment

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