Improving microalgal biomass production with industrial CO2 for bio-oil obtention by hydrothermal liquefaction

Abstract

An alternative for the cultivation of microalgae and its contribution to the reduction of greenhouse gases (GHGs) is the use of flue gas from a cement production plant. The microalgal biomass produced has the potential to become a valuable energy source in the form of bio-oil, using the Hydrothermal Liquefaction (HTL) process. Cultivation and conversion methods must be improved. For this reason, a laboratory-scale analysis was developed in which the range of nitrogen concentration with the highest cell growth was defined and the supply of simulated and real flue gas from a cement plant (SG and RG, respectively) in the cultivation of Chlorella sorokiniana UTEX® 1230 using two small pilot scale plants in different environments with 20 L tubular photobioreactors (PBRs) was assessed by varying the initial nitrogen concentration in the culture medium.The effect on cell culture productivity was found to be 10 times greater using RG than SG. For all nitrogen concentrations, lower protein levels were obtained with RG, as well as a better bio-oil yield for RG from the final biomass, with a maximum difference of 55%.The results suggest that the use of gases from the cement manufacturing process is conducive to the biofiltration and mitigation of polluting gases through the cultivation of microalgae with potential in the production of bio-oil.