Contribución energética de la digestión anaerobia al proceso de producción de biodiesel a partir de microalgas

Biodiesel production, one of the alternatives proposed to overcome the energetic crisis, has been strongly criticized because the feedstocks currently used compete with food production for fertile soils. The use of microalgae as feedstock would allow to overcome that barrier and its use involves advantages such as higher trans-esterifiable lipids accumulation and higher CO2 fixation rates. However, according to recent studies, its implementation would imply deficient and even negative energetic yields. The present work consists of an evaluation of the principal energetic benefits of anaerobic digestion as an energy recovery strategy from the biomass residues of the biodiesel production processes. The energy generation in the form of biogas was compared with the energy generated by the biodiesel, evaluating different scenarios related to 2 variables of the biomass, lipid accumulation and anaerobic biodegradability of the residue. The results show an important potential of the generated biogas, practically equal to the energy produced as biodiesel. The high energetic potential of the process is highlighted, but also the fact that it depends on factors like the accumulation of lipids suitable for trans-esterification in the microalgae, the biomass productivity and the degree of biodegradation achieved during the digestion of the residue.