Critical Review of Microalgae LCA Studies for Bioenergy Production

The cultivation of microalgae gained high attention within the last years because of their potential to substitute conventional bioenergy crops. To evaluate algal bioenergy production pathways already at an early stage, several life cycle assessment (LCA) studies have been performed, but their results and conclusions vary drastically. Against this background, this review gives a comparative analysis of 16 recent studies. To allow for a comparison, a meta-approach served to uniform the considered systems. System boundaries have been equalized and the energy return on investment (EROI) has been calculated for each study. Depending on the assumptions made on biomass productivity, lipid content, required energy, and the output of the system, the energetic performance was assessed. Large variations from 0.01 to 3.35 for the EROI could be derived.