Microalgae-driven carbon sequestration and bio-fertiliser: Steps towards a sustainable future

Conventional chemical and physical carbon dioxide (CO₂) sequestration methods are expensive due to high energy demands, and their long-term environmental implications are still unclear. Microalgae offer a promising alternative solution for efficiently sequestering CO₂ to produce biomass, which can be repurposed as natural fertilisers. Microalgal biofertilisers improve soil fertility, boost plant growth and soil microbial diversity, and increase stress tolerance while minimising reliance on synthetic fertilisers. Bio-fertiliser production and utilisation reduce the carbon footprint of traditional fertiliser production. This integrative approach has the capability for ensuring long-term application sustainability, however, it requires the development of cultivation systems for higher photosynthetic efficiency and biomass productivity, reduction in nutrient and water requirements, and addressing the need for substantial capital investment. This study aimed to assess the feasibility of microalgal carbon sequestration and examine its economic and environmental benefits. Microalgae-based systems not only capture CO₂ efficiently but also offer viable commercial application of the resultant biomass. This creates possible monetary incentives for corporations to invest in microalgal CO₂ sequestration to offset carbon emissions. Numerous funding sources are available for microalgal cultivation projects focusing on CO₂ sequestration while promoting biomass valorisation. The environmental and economic considerations with the exploration of wastewater integration and policy are reviewed to address the developmental challenges in implementing microalgal CO₂ sequestration for bio-fertiliser production. A circular economy integrating research and development, robust strain/s selection, infrastructure and logistics, etc, for CO₂ sequestration and bio-fertiliser generation is suggested. This strategy will contribute to a long-term, balanced approach to CO₂ mitigation, benefiting agricultural productivity.