IIT Guwahati researchers have pioneered a two-stage cultivation process that boosts CO2 capture and microalgal biomass production by over 25%. This innovation aims to lower costs for renewable biodiesel generation and offers a potential path for utilizing industrial carbon emissions, though the technology remains in the research phase.
Researchers at the Indian Institute of Technology (IIT) Guwahati have announced a breakthrough in bioenergy research with a new two-stage cultivation method for microalgae. This process is designed to improve the efficiency of carbon dioxide (CO2) capture while simultaneously increasing the production of microalgal biomass, which is used to create renewable fuels like biodiesel.
The challenge with using microalgae for carbon capture has historically been the balance between sustained growth and high CO2 exposure. High concentrations of CO2 can initially stimulate growth but often lead to acidification and nutrient depletion over time, slowing down the algae's development. To address this, the IIT Guwahati team, led by Professor Kaustubha Mohanty and research scholar Deepesh Singh Chauhan, developed a two-stage strategy.
In the first stage, the team cultured microalgae under a 15% CO2 concentration to facilitate rapid initial growth. In the second stage, the CO2 concentration was reduced to 5%, and specific nutrients—calcium and phosphorus—were introduced. This adjustment stabilized the pH levels and allowed for continued photosynthesis. The results, published in the journal *Renewable Energy*, showed a 25.7% increase in biomass production, a 35.4% rise in CO2 fixation, and 1.86 times higher lipid productivity compared to standard methods.
A significant barrier in the bioenergy sector is the high energy cost associated with harvesting and separating microalgal biomass from the growth medium. The IIT Guwahati process addresses this by using calcium to promote the self-flocculation of the microalgal cells. This causes the cells to clump together into compact flocks, allowing for a biomass recovery efficiency of 98.46%. This reduction in harvesting energy is a critical step toward making microalgal biorefineries more economically viable.
For investors and industry observers, the relevance of this research lies in the broader push toward decarbonization and renewable energy. Industries looking to reduce their carbon footprint are increasingly exploring carbon capture and utilization technologies. By potentially utilizing industrial flue gas as a continuous source of CO2 for microalgae cultivation, this technology aims to convert waste gas into useful bioenergy products.
However, it is important to note that this development is an academic breakthrough. While the results are positive at the laboratory scale, transitioning such technologies to industrial-scale operations involves significant challenges. These include the high capital expenditure required for large-scale photobioreactors, the ability to maintain consistent yields in uncontrolled environments, and the economic competitiveness of bio-based fuels against traditional fossil fuels and other renewable alternatives. The primary monitorable for this technology will be future pilot projects that attempt to replicate these efficiency gains outside of a controlled laboratory setting.