Abstract
The use of algae as a feedstock for biodiesel
production is a rapidly growing industry, in the United States
and globally. A life cycle assessment (LCA) is presented that
compares various methods, either proposed or under development,
for algal biodiesel to inform the most promising pathways
for sustainable full-scale production. For this analysis, the
system is divided into five distinct process steps: (1) microalgae
cultivation, (2) harvesting and/or dewatering, (3) lipid extraction,
(4) conversion (transesterification) into biodiesel, and (5) byproduct management. A number of technology options are
considered for each process step and various technology combinations are assessed for their life cycle environmental impacts. The
optimal option for each process step is selected yielding a best case scenario, comprised of a flat panel enclosed photobioreactor and
direct transesterification of algal cells with supercritical methanol. For a functional unit of 10 GJ biodiesel, the best case production
system yields a cumulative energy demand savings of more than 65 GJ, reduces water consumption by 585 m3 and decreases
greenhouse gas emissions by 86% compared to a base case scenario typical of early industrial practices, highlighting the importance
of technological innovation in algae processing and providing guidance on promising production pathways.
Original language | English |
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Pages (from-to) | 7060-7067 |
Journal | Environmental Science and Technology |
Volume | 45 |
DOIs | |
Publication status | Published - 2011 |
Keywords
- supercritical co2
- microalgae
- bioreactors
- extraction
- chitosan
- energy
- gas
- photobioreactors
- flocculation
- cultivation