In this research study, funded by ISTC’s Sponsored Research Program, Lance Schideman and his team partnered with Abbott Power Plant and the Urbana & Champaign Sanitary District to address critical challenges to practical demonstrations of biological CO2 capture systems and subsequent thermochemical conversion of biomass to biofuels.
The researchers developed the capability to harvest and store actual power plant flue gas samples in pressurized cylinders, then used these samples to study acclimation in algae cultivation systems dosed with flue gas. The project also demonstrated the use of anaerobic digestion to recover residual energy from the aqueous byproduct of hydrothermal liquefaction (HTLaq), which is generated during the conversion of algae or other organic feedstocks to biofuels.
The study shows that mixed culture algae are capable of using CO2 in flue gas and that the impact of the flue gas on algal growth rates was positive. Because higher flue gas injection rates resulted in higher productivity and lower CO2 removal efficiency, higher flue gas injection rates are preferable when the CO2 source is cheap and algae are considered the main product. Low flue gas injection rates would be preferable when the CO2 source is expensive or the CO2 removal efficiency is important. Heavy metal analysis showed that algal biomass will accumulate Zn, Pb, and Cu from flue gas, which can exceed certain animal feed regulatory limits.
The work also demonstrates that anaerobic treatment of HTLaq in combination with sewage sludge is feasible in both lab- and full-scale applications, which highlights the potential for enhancing energy recovery from sewage sludge through integration of hydrothermal liquefaction (HTL) technology with municipal wastewater treatment. Overall, this study highlights that integrating HTL technology with existing municipal sludge anaerobic digesters could significantly improve the bioenergy production of municipal wastewater treatment systems by 50 to 70% at a cost that is favorable compared to other alternatives.
Download the full report at http://hdl.handle.net/2142/102363.