1. Risk Assessment for Geologic Sequestration of CO 2 Presented to: West Coast Regional Carbon Sequestration Partnership Sacramento, California September 30-October 1, 2003 Sally M. Benson Lawrence Berkeley National Laboratory

2. Geologic Storage Goals  Long term effective containment (leakage of 0.01% per year)  No significant environmental impacts Groundwater Ecosystems Resources  No significant public health or safety impacts

3. Risk Assessment  Risk = Probability x Consequences  Probability = Likelihood of an event occurring  Consequences = Effects of the event occurring

4. Consequences at Leaking CO 2 Storage Sites

5. Features-Events-Processes- Methodology FeaturesEventsProcesses  Caprock thickness and permeability  Mineralogy of the storage zone  Faults and abandoned wells  Earthquakes  New exploration wells  Changes in groundwater use  Well blowout  Buoyancy-driven flow  Mineral trapping  Solubility trapping  Geomechanical changes in the caprock

6. FEP Risk Assessment Framework Consequences Features Events Processes Probabilistic Simulations Acceptable Leakage Rate Groundwater Impacts Ecosystem Impacts

7. Work Plan  Build on FEP data base developed by IEA Greenhouse Gas R&D Programme and CCP  Customize to Western Region scenarios  Run simulation cases to demonstrate methodology  Prepare report documenting procedures and consequences