Life Cycle Inventory Based on Primary Data of an Industrial Plant for the Cultivation of Chlorella Vulgaris

Abstract

Microalgae and cyanobacteria represent a valuable resource with great potential in the production of a large variety of high-added value products in the nutraceutical, cosmetic, pharmaceutical, and food sectors. However, the commercialization of microalgal systems and biorefineries is limited by environmental and economic sustainability concerns. Many life cycle assessments (LCAs) have been conducted so far, but they have the crucial limitation of using data extrapolated from lab-scale experiments or the literature, thus providing qualitative and uncertain projections. In this work, an industrial-scale plant's life cycle inventory (LCI) is compiled with primary data and analyzed. The plant is installed in Sicily (Italy) and has a 1200 kgDW year–1 capacity in the production of Chlorella vulgaris microalgae. The cultivation is performed in vertically stacked horizontal photobioreactors (PBRs) with a total volume of 40.4 m3. Dewatering is performed by centrifugation, producing a final algal suspension at ~200 gDW L–1. Energy, nutrients, water, chemicals, and infrastructure materials are inventoried to characterize the operation and construction. One kg of dry algae biomass is the functional unit chosen to report all elementary input/output flows. The results are compared with relevant LCIs from the literature, providing a picture of the current status of microalgae production in large-scale plants.