Are CAM Crops a Sustainable Bioenergy Feedstock? - the Case of the Prickly Pear Cactus for Ethanol Production in Semi-Arid Regions of Argentina

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

Buenos Aires

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

PanAM RCN

With the growing focus in developing energy from low-input biomass, crassulacean acid metabolism (CAM) crops represent a potential opportunity for biofuels in arid and semi-arid marginal lands, avoiding competition with food for land and water. The aim of this study is to evaluate the impact of water consumption in the life cycle of ethanol production by fermentation of cladodes of prickly pear cactus (Opuntia ficus-indica (L.) Miller), in a semi-arid region of Argentina. For this, the water footprint of 1 MJ of energy is calculated considering the agricultural and industrial unit processes.Green and blue water footprints are accounted and the sustainability assessment for both water footprints is presented. The results show that ethanol from O. ficus-indica has water footprint values significantly lower than the values of biofuels obtained from conventional crops. This is because the CAM mechanism in O. ficus-indica improves efficiency of water utilization than C3 crops (such as soybean and rapeseed) and C4 crops (such as corn and sugar cane), giving it the possibility to produce greater amount of dry mass per unit of cultivated land. The sustainability assessment shows better results for O. ficus-indica ethanol than for conventional biofuels produced in semi-arid regions of Argentina. However, O. ficus-indica ethanol is more impacting than conventional biofuels produced in other regions of the country, such as the Pampean region. This is due to water scarcity in the semi-arid regions. The study demonstrates the good potential, in terms of water consumption, of CAM crops as feedstock for bioenergy in semi-arid region of Argentina