Environmental assessment of industrial production of microalgal biodiesel in central-south Chile

Abstract

Biofuels from microalgae have the potential to replace fossil fuels, without competing with other products derived from crops. This study aims to perform a cradle-to-gate Life Cycle Assessment of the industrial production of microalgal biodiesel, using an autochthonous Chilean Phaeodactylum tricornutum strain, considering 1 MJ of biodiesel as the functional unit. For the compilation of the Life Cycle Inventory, real experimental data were obtained from the pilot-scale cultivation in a photobioreactor (PBR) module located in the city of Concepción, in Chile. The scale-up to the industrial plant considers that PBR modules are of the same size as those used in the pilot-scale. The Life Cycle Impacts Analysis considered the ReCiPe 2016 Endpoint (H) V1.00 method. Results show that the whole process contributes to a total of 5.74 kgCO2eq per MJ of biodiesel produced. PBR construction materials and energy consumption are the main contributors to the life cycle environmental impacts. The sensitivity analysis shows that energy consumption, water reuse and transportation distance of seawater from ocean to the industrial plant are the critical parameters that most affect the overall environmental performance of the system. The rate of water reuse is particularly critical to the global warming potential. Results also show that the valorization of co-products is an important aspect to improve the environmental performance of microalgal biodiesel production. Therefore, this study supports the decision-making process in biofuel production to promote the development of sustainable pilot and large-scale algae-based industry.