Is Biodiesel from Microalgae a Real Energy Option? Preliminary Life Cycle Assessment (LCA) of a Multigeneration System

RODRÍGUEZ, P.D.; ARENA, A.P.; CIVIT, B.; PIASTRELLINI, R.

Buenos Aires

Conferencia; 2nd RCN Conference on Pan American Biofuels & Bioenergy Sustainability; 2016

PanAM RCN

Global predictions have indicated that the world population will need 50% more fuel, 50% more water and a 50-80% reduction in carbon dioxide (CO ) emissions by the year 2050. In this context, renewable energies will have an important role replacing fossil fuels in critical issues, especially biofuels (biodiesel and bioethanol), since they can be used in transportation and electricity generation and they can store energy. Many authors have pointed out the microalgae as the major raw material for biofuels production, principally biodiesel. This is possible because the microalgae have higher productivities than crops, they can accumulate large amounts of fatty acids (the feedstock for biodiesel production), they consume CO , they do not compromise the production offood and they can grow in wastewater. Therefore, the production of biodiesel from microalgae is a well explored topic. Nevertheless, it is facing numerous economic and technological challenges that need to be solved before biodiesel becomes a real alternative to fossil fuels usage. Also, many energetic and environmental analysis have been conducted and they exhibit very divergent results that put the sustainability of microalgae-based biodiesel into doubt. Consequently, biodiesel from microalgae production is an issue that needs to be fully explored. The aim of this study is to evaluate the environmental impacts in the life cycle of a multigeneration system for biofuels and co-productsproduction through microalgae cultivation in compact tubular photobioreactors (PBR). For this purpose, the Life Cycle Assessment (LCA) based on the recommendations of the ISO 14040 is performed. The results show that the production of biomass from microalgae has a large amount of energy inputs, which involve another environmental impacts, like greenhouse gases (GHG) emissions. For that reason, it is necessary to take into account the production of various co-products to enhance the environmental performance of the microalgae-derived biodiesel. Multigeneration strategies exhibit a big potential to produce energy and multiple products from microalgae. As a consequence, biodiesel from microalgae will become an alternative source of energy only if it is produced into multigeneration systems. This study also demonstrates the importance of LCA to evaluate different scenarios into multigeneration systems and to indicate critic points in the biofuels production chain. In addition, the system under study presents some challenges to solve with LCA, such as the allocation between multiproducts, the CO consumption by microalgae, the use of wastewater as nutrient for microalgae and the inclusion of the waste treatment into the system.