Microalgal biomass has a high CO2 fixation
and growth
rate when using CO2 as a carbon source. Moreover, biomass
can also be employed as a carbon resource to produce biofuels and
chemicals. As the growth rate of extremophilic microalgae remains
unaffected by harsh conditions, the present study proposes that these
microalgae (such as Galdieria sulphuraria) are a rapidly growing carbon resource for syngas production. Hence,
two different experiments were performed as part of this study: (1)
cultivation of G. sulphuraria under
outdoor conditions and (2) conversion of G. sulphuraria into syngas. The productivity of G. sulphuraria under mixotrophic condition (0.82 g L–1 d–1) was about 1.6 faster than a widely cultivated Chlorella sp. HS2. Moreover, G. sulphuraria was converted into syngas using CO2 as a co-feedstock.
The simultaneous reduction of CO2 and the oxidation of
volatile matter (VM) from the thermolysis of G. sulphuraria promoted syngas formation. The chemical reaction was influenced
by the molecular size of the VMs. In the presence of the Ni catalyst,
low-molecular-weight VMs were formed owing to chemical bond scissions.
Syngas formation under CO2 doubled compared with that under
inert conditions. The findings suggest that G. sulphuraria is a feasible carbon source for CO2 fixation and chemical
production.