Using eddy covariance to detect leaks from CO₂ sequestered in deep aquifers

This chapter describes the eddy covariance method of measuring earth-atmosphere CO₂ exchange, including past applications to measurements of volcanic venting of CO₂. It assesses the ability to detect leaks from geologic CO₂ reservoirs by comparing expected leakage rates to typical ecological flux rates. While the character and magnitude of ecological fluxes are well established, reservoir leakage rates and areas are uncertain. Fairly conservative estimates based on ensuring the economic viability of CO₂ sequestration are constructed. The estimates of leakage rate and area yield leakage fluxes that range from 1 to 10 times the magnitude of typical ecological fluxes. This approach shows promise for the monitoring of CO₂ sequestration in deep aquifers. Leak detection is shown to be a simpler problem than leak quantification, but both can in principle be accomplished using eddy covariance under conditions favorable for the measurement.