CO₂ nanobubbles (CNBs): A potential technology to enhance CO2 capture for carbon farming

Carbon capture and utilization (CCU) strategies have been developed to mitigate CO2 emission, aiming to recycle excessive emitted CO2 and utilize it to produce valuable products. Carbon farming is one of the solution strategies in the CCU regime, in which CO2 are recovered for plant growth and crop production. The current challenge of the approach is how to enhance atmospheric CO2 capture and effectively deliver to plants for their photosynthesis. CO2 nanobubble (CNB) technology has posed being a potential solution, regarding the high stability in captured CO- gas with excessive amounts. The properties may facilitate bulk CO2 capture, delivery, and probably increase of CO2 concentration around plants. To ensure that CNB could act as a carrier medium to create CO2-enriched microenvironments for plants that would potentially improve carbon uptake and productivity. We have investigated the feasibility of CNBs as a CO2 delivery approach for agricultural CO2 fertilization. A CNB generation system was integrated with an automated irrigation system and tested under two delivery modes—spraying and dripping—within controlled small chambers (0.12 m3; 0.3 × 0.3 × 1.3 m). Results showed that spraying method was more effective than dripping in elevating atmospheric CO2 concentration. CNB spraying fog released CO2 rapidly from nozzle heads, producing higher localized CO2 levels, whereas the dripping method increased CO2 concentration only partially due to incomplete CO2 release from the bubbles. Overall, these findings demonstrate the potential of CNBs as a practical tool for coupling CO2 capture with carbon farming. CNBs provide a feasible method to recycle industrial CO2 emissions, enhance CO2 utilization efficiency, and support sustainable agricultural production systems.