Quantitative sustainability analysis of third generation biofuels using process data from microalgae biorefinery

Abstract

Microalgae biorefineries have been proposed as an important strategy for enhancing the economic profitability of bioproducts, which depends on the biotechnological potential of each species, associated with environmental conditions and technological approaches. The biorefinery concept applied to microalgae also implies valorization of residual biomass, converting it into biofuels and/or high value compounds. This study aimed to analyze the biochemical composition and the technical and economic feasibility of a biorefinery based on Phaeodactylum tricornutum cultivated in an outdoor pilot-scale bubble-columns photobioreactor, under natural conditions in Chile, for production of biofuels and high-value compounds. P. tricornutum biomass has a potential biochemical composition for using in an integrated biorefinery approach, mainly in order to optimize the environmental and economic feasibility of the process. Three different scenarios were proposed for the production of biofuels and high-value compounds. The most profitable scenarios were those that considered fucoxanthin and protein production and commercialization, due to the high price of these compounds on the market. The production of biomass as a raw material exclusively targeted for biofuel production showed itself not to be feasible under the conditions considered in the analysis. Furthermore, the assumption of economies of scale was shown to be a critical factor for the biomass price and feasibility of this approach. Technical and economic analysis is essential to identify economic bottlenecks and opportunities for addressing a microalgae product portfolio to the different market scenarios, in order to assist decision-makers and propose improvements in the cultivation and downstream processes.