Towards a Method for Leakage Quantification and Remediation Monitoring in the Near-surface at Terrestrial CO2 Geologic Storage Sites

The Intergovernmental Panel on Climate Change (IPCC) states that quantification of leakage emissions at CO2 geological storage sites will require direct monitoring techniques rather than standardized emissions factors. In addition, IPCC guidelines state that leakage emissions should be distinguished from natural baseline emissions. Current methods measure only bulk CO2 emissions and therefore do not have the capability to separate these components. We discuss that a process-based soil gas approach could potentially be used with an open chamber emissions quantification method to translate process-based concentration data into surface flux rates. In doing so, the various components of surface gas flux could be attributed, separated and individually quantified. We use soil gas data from the ZERT controlled release experimental site as the basis for our discussion and show that such a method may improve the accuracy and ease of leakage quantification. For accounting purposes, such capabilities could be used to more accurately assess the number of credits to be surrendered for leakage. For monitoring purposes, added benefits could include delineating the spatial extent of leakage emissions and providing real-time information on the effectiveness of remediation efforts. (C) 2017 The Authors. Published by Elsevier Ltd.