Life cycle assessment of a microalgae biomass cultivation, bio-oil extraction and pyrolysis processing regime

Scott Grierson*, Vladimir Strezov, Jonas Bengtsson

*Corresponding author for this work

    Research output: Contribution to journalArticle

    63 Citations (Scopus)

    Abstract

    Life cycle assessment (LCA) of a microalgae biomass cultivation, bio-oil extraction and pyrolysis processing regime is a useful means to gauge the likely environmental impact of this prospective new development on an industrial scale. Coupled to thermal conversion via slow pyrolysis, the prospect of biologically 'sequestering' carbon derived from microalgae biomass as biochar, added to soil, is considered. However, an intensive closed culturing photobioreactor system coupled to a pyrolysis process incurs a net increase in global warming and overall life cycle impact, notwithstanding biochar application to soil. Results indicate that up to 50% of environmental impact in certain categories stems from the upstream influence of fertiliser production. Energy used in flue gas delivery and pumping during cultivation is also considerable, suggesting that current practice in closed cultivation systems does not yet adequately trade-off biomass productivity against operating intensity. Drying of the harvested microalgae biomass for pyrolysis processing is potentially a major hurdle in terms of process viability also. Overall, utilisation of nutrients derived from waste streams, integrating renewable energy and capture of process heat for more efficient drying are essential levers for reducing the environmental impact of this proposition.

    Original languageEnglish
    Pages (from-to)299-311
    Number of pages13
    JournalAlgal Research
    Volume2
    Issue number3
    DOIs
    Publication statusPublished - Jul 2013

    Keywords

    • microalgae
    • life cycle assessment
    • pyrolysis
    • bio-CCS

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