Estimating geological CO₂ storage security to deliver on climate mitigation

Area of Science:

• Environmental Science
• Geoscience
• Climate Change Mitigation

Background:

• Carbon capture and storage (CCS) is crucial for meeting Paris Agreement CO2 reduction targets.
• Public and regulatory confidence in geologic CO2 storage security is currently limited.
• Addressing storage security concerns is vital for widespread CCS implementation.

Purpose of the Study:

• To develop and utilize a numerical program for assessing CO2 storage security and atmospheric leakage over 10,000 years.
• To quantify geological subsurface CO2 retention and surface leakage rates.
• To evaluate the impact of regulatory frameworks on long-term CO2 storage security.

Main Methods:

• Development of a numerical program integrating subsurface CO2 retention and surface leakage models.
• Simulation of CO2 storage security over a 10,000-year timescale.
• Analysis of storage security under varying regulatory scenarios and well densities.

Main Results:

• Well-regulated geologic CO2 storage with moderate well densities shows a 50% probability of annual leakage below 0.0008%.
• Over 98% of injected CO2 is projected to remain in the subsurface for 10,000 years under realistic regulatory conditions.
• Even under inadequate regulation, over 78% of CO2 is estimated to be retained over 10,000 years.

Conclusions:

• Geological storage of CO2 presents a secure and viable climate change mitigation strategy.
• Robust regulation is key to maximizing the security and effectiveness of CCS.
• Further research into the long-term subsurface behavior of CO2 is necessary to reduce uncertainties.