TAG: GS 3: ECOLOGY AND ENVIRONMENT
THE CONTEXT: Researchers at IIT Jodhpur have developed a groundbreaking method that combines algae-assisted microbial fuel cells to capture carbon dioxide, treat wastewater, and generate power simultaneously.
- This technology represents a promising alternative to traditional carbon capture and sequestration (CCS) methods, offering multiple benefits in environmental remediation and energy production.
ALGAE-ASSISTED CARBON CAPTURE PROCESS
- Absorption of CO2 from Flue Gas
- The process initiates by cooling the flue gas from thermal power stations and industrial plants using a heat exchanger.
- The cooled flue gas is then directed to a sieve-plate absorption column, where sodium carbonate supplemented wastewater absorbs CO2, producing flue-gas-derived bicarbonates (FGDBs).
- Utilization in Algae-Assisted Microbial Fuel Cells (MFC)
- FGDBs are utilized in plastic bag photobioreactors (PBRs) combined with algae-assisted microbial fuel cells.
- This novel integration facilitates biochemical CO2 sequestration while simultaneously generating power and promoting algae biomass growth.
ADVANTAGES OVER CONVENTIONAL METHODS
- Efficiency of CO2 Fixation
- Compared to the conventional method of bubbling flue gases into algal ponds, the indirect biochemical route adopted by IIT Jodhpur proves more efficient.
- It converts CO2 into carbonates, enhancing the solubility of inorganic carbon in water, thereby fostering increased carbon retention in the water.
- Closed Systems and Wastewater Usage
- The use of closed systems like PBRs is highlighted as preferable to open ponds, as they prevent decomposition of bicarbonates into CO2 and maintain pH levels.
- Additionally, the technology utilizes wastewater, utilizing a thermo-tolerant algal strain (Chlorella vulgaris) capable of thriving in such conditions.
POWER GENERATION AND SCALING CHALLENGES
- Algae in Microbial Fuel Cells
- The integration of algae into microbial fuel cells generates electricity.
- This bio-electrochemical process harnesses the metabolic activity of microorganisms breaking down organic matter in wastewater, releasing electrons that produce electric current.
- Scalability and Limitations
- While theoretically, all available flue gas can be used to grow algae, scalability presents challenges.
- A tonne per day of CO2 capture demands a substantial algae culture area, limiting the practical scale of operation.
- Moreover, only a small fraction of algae is used for power generation, leaving the majority available for bioenergy purposes.
FUTURE PROSPECTS AND DEVELOPMENT
- Further Refinement and Research
- Technology requires refinement and further research.
- Developmental avenues include enhancing microbial consortia or genetically engineered strains, comprehensive mass balance studies, determination of feed flow rates, and retention times for efficient CO2 capture.
- Device Optimization
- Enhancements to the device itself could involve integrating specialized gas diffusing devices (spargers) for a stable gas supply, ensuring sustained algal growth.
- IIT Jodhpur’s innovative algae-assisted microbial fuel cell technology showcases a promising approach to address multiple environmental challenges simultaneously.
- While requiring further development and refinement, its potential to capture CO2, treat wastewater, and generate power represents a significant step towards sustainable and efficient energy solutions.