Characteristics and monitoring plan in the atmosphere of CO₂ leakage from carbon capture and storage projects

Global warming is a pressing issue that is primarily caused by the increasing levels of carbon dioxide (CO₂) in the atmosphere. Achieving carbon neutrality, or climate neutrality, has become a global consensus, leading governments to implement policies and regulations. Carbon capture and storage (CCS) has great potential for reducing the concentration of CO₂ in the atmosphere. However, the sealed CO₂ in geological formations is susceptible to leakage. In this study, we employed the heavy gas diffusion model to show the leakage characteristics of CO₂ in the atmosphere under different conditions. According to the influence of CO₂ concentration in the air on humans, combined with the distribution of global carbon dioxide geological storage area and population density, the degree of damage under different leakage conditions is discussed. The results show that when the wind speed is 0.5 m/s, the leakage speed is in the range of 0–120 kg/s, and the maximum dangerous distance from the downwind is 165 m. In areas with wind grade is above 3 and the population density is less than 100 people/km², CO₂ leakage does not pose a threat to human health. Our results show the three-dimensional distribution characteristics of the geological storage of CO₂ after a leakage in the atmosphere and establish a risk matrix based on the hazard area and population. Furthermore, we quantitatively evaluate the potential damage caused by leakage. Based on these findings, we propose a layout scheme for monitoring sites at different storage locations, providing a foundation for CO₂ geological storage monitoring efforts.