Energy recovery from microalgal biomass via enhanced thermo-chemical process

•Thermo-chemical process using low lipid microalgal biomass.•CO2 co-feed impact on the thermo-chemical processes.•Substantial tar reduction under the presence of CO2.•Enhanced pyrolysis and gasification under the presence of CO2.•Universal application in thermo-chemical process.

This work showed that microalgae having low lipid content has high potential for energy recovery via thermo-chemical processes. As an example, Microcystis aeruginosa (M. aeruginosa) was considered and tested. Specifically, this work verified that the growth rate of M. aeruginosa was extremely fast compared to other microalgae (as a factor of ∼10). Moreover, this work investigated the CO2 co-feed impact on thermo-chemical processes (pyrolysis/gasification) using M. aeruginosa. Introducing CO2 in the thermo-chemical process as reaction media or feedstock can enhance the efficiency of thermo-chemical processes by expediting the cracking capability of condensable hydrocarbons (tar). The generation of CO was enhanced as a factor of ∼2. Further generation of H2 could be achieved in the presence of CO2. Thus, utilizing CO2 as reaction media or chemical feedstock can modify the end products into environmentally benign and desirable ones. The CO2 co-feed impact on thermo-chemical processes with lingo-cellulosic biomass can be universally applied.