Leakage risks of geologic CO2 storage and the impacts on the global energy system and climate change mitigation

Abstract

This study investigated how subsurface and atmospheric leakage from geologic CO 2 storage reservoirs could impact the deployment of Carbon Capture and Storage (CCS) in the global energy system. The Leakage Risk Monetization Model was used to estimate the costs of leakage for representative CO 2 injection scenarios, and these costs were incorporated into the Global Change Assessment Model. Worst-case scenarios of CO 2 leakage risk, which assume that all leakage pathway permeabilities are extremely high, were simulated. Even with this extreme assumption, the associated costs of monitoring, treatment, containment, and remediation resulted in minor shifts in the global energy system. For example, the reduction in CCS deployment in the electricity sector was 3% for the Bhigh^leakage scenario, with replacement coming from fossil fuel and biomass without CCS, nuclear power, and renewable energy. In other words, the impact on CCS deployment under a realistic leakage scenario is likely to be negligible. We also quantified how the resulting shifts will impact atmospheric CO 2 concentrations. Under a carbon tax that achieves an atmospheric CO 2 concentration of 480 ppm in 2100, technology shifts due to leakage costs would increase this concentration by less than 5 ppm. It is important to emphasize that this increase does not result from leaked CO 2 that reaches the land surface, which is minimal due to secondary trapping in geologic strata above the storage reservoir. The overall conclusion is that leakage risks and associated costs will likely not interfere with the effectiveness of policies for climate change mitigation.

Bearing the Cost of Stored Carbon Leakage

“…Moreover, it is interesting to note that the ordering across stringency of the climate targets is reversed for fossil fuel and biomass based CCS: The more stringent the scenario considered, the lower the impact on BECCS and the higher the reduction of fossil based CCS. This result is in line with the intermediary role of fossil fuel based CCS found e.g., in Rogelj et al (2015), van der Zwaan and Smekens (2009) and Deng et al (2017), even if these two latter studies did not consider stringent scenario such as the 1.5°C (550 GtCO 2 ).…”

“…The percentage of leaked emission on the total captured between 2015 and 2100 is however similar to the previous scenarios. If compared to Deng et al (2017), our results show higher percentage of emission leaking over the century given similar leakage rates. This is due to their assumption that most of leaked emissions do not reach the surface, but are priced and thus have a negative impact on CCS deployment.…”

“…Another problem caused by CO 2 losses is ground water contamination. Seepage could reach groundwater aquifers, rather than reaching directly the atmosphere surface (Bielicki et al, 2015;Deng et al, 2017). This would lower the aquifer water pH and could lead to the release of harmful metals, an effect known as acidification (Little and Jackson, 2010).…”

“…According to Bielicki et al (2015) only the case with 10 −12 m 2 permeability would conform to the storage permanence goal of 1% leakage. These permeability assumptions have been tested in the GCAM model by Deng et al (2017), obtaining leakage over the twenty-first century of between~0.003 and 0.2% 3 . Another finding is that with a low injection rate, leakages are higher at the beginning, while in the long term this might change.…”

Recent developments and challenges ahead in carbon capture and sequestration technologies

“…So, considering such formations for secure CO 2 storage will represent significant challenges. The uncertainties in quantifying leakage rates and expected cost of leakage risk is unlikely to significantly hinder global CCS deployment or the effectiveness of policy for mitigating climate change [91]. Table 4 shows the earth and atmospheric hazards because of various risk elements [83,92,93].…”