A comparative life cycle assessment (LCA) was conducted on 20 scenarios of microalgae cultivation. These scenarios examined the utilization of nutrients and CO(2) from synthetic sources and waste streams as well as the materials used to construct a photobioreactor (PBR). A 0.2-m(3) closed PBR of Chlorella vulgaris at 30%-oil content by weight with the productivity of 25 g/m(2) × day was used as a case study. Results of the study show that the utilization of resources from waste streams mainly avoided global warming potential (GWP) and eutrophication impacts. Impacts from the production of material used to construct the PBR dominate total impacts in acidification and ozone depletion categories, even over longer PBR lifetimes; thus, the choice of PBR construction materials is important.
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