Life-Cycle Assessment of Biodiesel Production from Microalgae

TLDR

High microalgae yields have spurred interest, yet it remains uncertain whether biodiesel production is environmentally favorable and which process steps require optimization. The study evaluates the environmental impacts of producing biodiesel from microalgae. A comparative life‑cycle assessment of a virtual facility examined the entire chain—from biomass cultivation under nominal fertilization or nitrogen starvation, to dry or wet extraction, and compared the best scenario with first‑generation biodiesel and oil diesel. Results confirm microalgae’s potential as an energy source but underscore the need to lower energy and fertilizer use, suggesting nitrogen‑stress control, wet extraction optimization, and anaerobic digestion of oilcakes to reduce external energy demand and recycle fertilizers.

Abstract

This paper provides an analysis of the potential environmental impacts of biodiesel production from microalgae. High production yields of microalgae have called forth interest of economic and scientific actors but it is still unclear whether the production of biodiesel is environmentally interesting and which transformation steps need further adjustment and optimization. A comparative LCA study of a virtual facility has been undertaken to assessthe energetic balance and the potential environmental impacts of the whole process chain, from the biomass production to the biodiesel combustion. Two different culture conditions, nominal fertilizing or nitrogen starvation, as well as two different extraction options, dry or wet extraction, have been tested. The best scenario has been compared to first generation biodiesel and oil diesel. The outcome confirms the potential of microalgae as an energy source but highlights the imperative necessity of decreasing the energy and fertilizer consumption. Therefore control of nitrogen stress during the culture and optimization of wet extraction seem to be valuable options. This study also emphasizes the potential of anaerobic digestion of oilcakes as a way to reduce external energy demand and to recycle a part of the mineral fertilizers.