Session 20. Oral Presentation for: Causal networks as a tool to assess environmental risk of CO₂ leakage

Abstract

Presented on 28 May 2025: Session 20

The role of carbon capture and storage (CCS) as a quantitatively significant emissions reduction tool for Australia and globally is acknowledged by many. One perceived challenge that CCS faces relates to the potential for adverse environmental impacts due to the risk of leakage. CSIRO has completed a study, commissioned by the International Energy Agency’s Greenhouse Gas R&D Programme (IEAGHG), using causal networks a framework allowing identification of steps which provide insight into cause-and-effect relationships. The network describes a series of drivers, activities and stressors that could be at play, generically speaking, during geological carbon storage together with processes that may arise if leakage were to occur where endpoints or impacts are described. An assessment of the risk, its likelihood and consequences are explained and supported by a range of peer-reviewed resources to illustrate actual impacts. Case studies, analogues and pilot tests have been instrumental in informing risks and consequences. The report demonstrates that while leakage (i.e. via compromised well bores or unforeseen geological conditions) could be material in rare circumstances, environmental impacts via pathways from stressors to endpoints (e.g. air quality, marine biodiversity) are low. If appropriate geological appraisal is conducted, the geological leakage risk remains low, and mitigation steps can be used to manage remaining risks and impacts of CCS.

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