Farmland degradation caused by radial diffusion of CO2 leakage from carbon capture and storage

Abstract Carbon capture and storage (CCS) may result in negative environmental impacts if CO2 escapes into the soil layer from deep geological storage formations. In particular, little is known about the spatial scope of possible impacts of CO2 leakages. This study designed and implemented a CO2 point-source shallow release experiment to simulate CCS leakage at a rate of 1.0 L min-1 and a depth of 1.5 m. The scope of crop and farmland responses to CO2 leakage were examined, with a focus on spring wheat. The experimental site had a radius of 9.0 m, and the leaked CO2 was found to influence soil CO2 concentrations up to 4.0 m from the source, or 2.67 times the depth of the leak. Furthermore, the influence radius of the CO2 leak on spring wheat height was about 1.0 m, which was 0.67 times the depth of the leak. The morphological characteristics of wheat observed directly above the leak were approximately 30–50% lower than the background levels (9.0 m from the source). CO2 leakage could therefore result in wheat field degradation along the soil surface. These findings suggest that a set of empirical parameters to assess the scope of the negative influence of CCS leakage on agriculture should be developed. Overall, the results indicate a concentric pattern of farmland and crop degradation with distance from the CCS leakage source, which may help to deepen understanding of the safety of CCS.