It is all very well to complain about problems in the legislation around leakage. But there is another question: Will the CO2 actually leak? The short answer is "yes".
I have been browsing though the Intergovernmental Panel on Climate Change report on CCS. I should point out that this report favours CCS. However, even this document contains alarming stuff."With regard to global risks, based on observations and analysis of current CO2 storage sites, natural systems, engineering systems and models, the fraction retained in appropriately selected and managed reservoirs is very likely to exceed 99% over 100 years, and is likely to exceed 99% over 1000 years."
That is clear. It will leak. The question is how fast. Also note the qualification: "appropriately selected and managed". How confident are we of this appropriate selection and management? To make an analogy, are we satisfied that our various governments managed quarantine properly during the pandemic and selected appropriate sites to accommodate incoming travelers? My view is that the virus leaked out of quarantine far too often and in many cases through obvious failures, including using unsuitable sites for quarantine. Therefore, I am not at all confident that the CO2 reservoirs will be appropriately selected and managed.
The report covers failures which could occur.
"In the first case, injection well failures or leakage up abandoned wells could create a sudden and rapid release of CO2."
"In the second scenario, leakage could occur through undetected faults, fractures or through leaking wells where the release to the surface is more gradual and diffuse."
Back to our inadequate legislation. I do not believe that the legislation was written incompetently. Rather, I believe that the legislation is evidence that leak-proof CCS is not possible and that the people who decided on the content of the legislation know that.