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Locating and quantifying greenhouse gas emissions at a geological CO 2 storage site using atmospheric modeling and measurements
Author(s) -
Luhar Ashok K.,
Etheridge David M.,
Leuning Ray,
Loh Zoe M.,
Jenkins Charles R.,
Yee Eugene
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2014jd021880
Subject(s) - greenhouse gas , atmospheric dispersion modeling , environmental science , tonne , methane , carbon capture and storage (timeline) , monte carlo method , inversion (geology) , atmosphere (unit) , meteorology , petroleum engineering , air pollution , geology , engineering , climate change , chemistry , statistics , waste management , mathematics , physics , oceanography , organic chemistry , structural basin , paleontology
The Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) Otway Project is Australia's first demonstration of the geological storage of carbon dioxide (CO 2 ), where about 65,000 metric tons of fluid consisting of 92% CO 2 and 8% methane (CH 4 ) by mass have been injected underground. As part of the project objective of developing methodologies to detect, locate, and quantify potential leakage of the stored fluid into the atmosphere, we formulate an inverse atmospheric model based on a Bayesian probabilistic framework coupled to a state‐of‐the‐art backward Lagrangian particle dispersion model. A Markov chain Monte Carlo method is used for efficiently sampling the posterior probability distribution of the source parameters. Controlled experiments used to test the model involved releases of the injected fluid from one of the nearby wells and were staggered over 1 month. Atmospheric measurements of CO 2 and CH 4 concentrations were taken at two stations installed in an upwind‐downwind configuration. Modeling both the emission rate and the source location using the concentration measurements from only two stations is difficult, but the fact that the emission rate was constant, which is not an unrealistic scenario for potential geological leakage, allows us to compute both parameters. The modeled source parameters compare reasonably well with the actual values, with the CH 4 tracer constraining the source better than CO 2 , largely as a result of its 6 times higher signal‐to‐noise ratio. The results lend confidence in the ability of atmospheric techniques to quantify potential leakage from CO 2 storage as well as other source types.