PNNL

Abstract

The FutureGen 2.0 Project will design and build a first-of-its-kind, near-zero emissions coal-fueled power plant with carbon capture and storage (CCS). To assess storage site performance and meet the regulatory requirements of the Class VI Underground Injection Control (UIC) Program for CO2 Geologic Sequestration, the FutureGen 2.0 project will implement a suite of monitoring technologies designed to 1) evaluate CO2 mass balance and 2) detect any unforeseen loss in CO2 containment. The monitoring program will include direct monitoring of the injection stream and reservoir, and early-leak-detection monitoring directly above the primary confining zone. This preliminary modeling study focuses on leakage scenarios into the first permeable unit above the primary confining zone (Ironton Sandstone) to support assessment of early-leak detection capabilities. An updated version of the model will eventually be used to assess potential impacts on the lowermost USDW aquifer (Saint Peter Sandstone) for a range of theoretical leakage scenarios. This preliminary modeling evaluation considers both pressure response and geochemical signals in the overlying Ironton Sandstone. This model is independent of the FutureGen 2.0 reservoir model in that it does not simulate caprock discontinuities, faults, or failure scenarios. Instead this modeling effort is based on theoretical, volumetric-rate based leakage scenarios. The scenarios include leakage of 1% of the total injected CO2 mass, but spread out over different time periods [20, 100, and 500 years] with each case then yielding a different mass flux (i.e. smaller mass fluxes for longer duration leakage cases]. Additionally, a brine leakage scenario was considered using a similar volumetric leakage as the 20 year 1% CO2 case. A framework for the comparison and monitoring considerations of the cases was developed based on the arrivals of selected pressure and geochemical thresholds at different distances from the leakage point and different vertical positions within the Ironton Sandstone. These preliminary results, and results from an updated model that incorporates additional site specific characterization data, will be used to guide any required refinement the monitoring system design.