Certainly, the technology exists and there's a lot of on-going research on CO2 sequestration. Yet, in my opinion, injecting CO2 just to settle the fracking toxic compounds and to prevent them to reach shallow aquifers through caprock is fissures is a bit risky. What if the well casing has a breach at shallow depths and you are injecting CO2? That would go directly to the shallow aquifer... This, although sounding a bit like science fiction may happen. It actually happened, but while injecting just water in Landau (in Germany, a deep geothermal project). The ground level raised centimeters due to the overpressure at the shallow aquifer. Consequence: cracks. Many. Therefore, while the idea is good (and CO2 certainly precipitates or stays in supercritical state), must be "handled with care".
Published by Andres Alcolea Rodriguez, Head of Groundwater Division, TK Consult AG
Certainly, the technology exists and there's a lot of on-going research on CO2 sequestration. Yet, in my opinion, injecting CO2 just to settle the fracking toxic compounds and to prevent them to reach shallow aquifers through caprock is fissures is a bit risky. What if the well casing has a breach at shallow depths and you are injecting CO2? That would go directly to the shallow aquifer... This, although sounding a bit like science fiction may happen. It actually happened, but while injecting just water in Landau (in Germany, a deep geothermal project). The ground level raised centimeters due to the overpressure at the shallow aquifer. Consequence: cracks. Many. Therefore, while the idea is good (and CO2 certainly precipitates or stays in supercritical state), must be "handled with care".