The major benefits that could be derived from successful carbon dioxide (CO{sub}2) or mixed gas (CO{sub}2/nitrogen) injection in an enhanced coalbed methane (ECBM) recovery scheme are twofold: (1) enhancement of the coalbed methane (CBM) recovery factors and production rates to achieve commercial economics and (2) reducing greenhouse gas emissions to the atmosphere by permanently storing the CO{sub}2 in deep coal beds. Optimal ECBM operation will depend on both production economics and CO{sub}2 storage economics (if there is monetary value or credit for the CO{sub}2 stored). These two aspects are often conflicting depending on the set of economic and environmental factors considered. The CO{sub}2 credit must be calculated on the basis of net CO{sub}2 avoided. In essence, the CO{sub}2 produced in the process of capturing, compressing, pipelining and injecting the CO{sub}2 must be accounted for when computing net reductions in CO{sub}2 emissions attributable to the project. This necessitates a detailed description and modelling of the surface facilities involved in the ECBM operation. In the Alberta ECBM field program [1] led by the Alberta Research Council, SNC-Lavalin was contracted to develop a technical and financial computer model to simulate design and operation of all the facilities required to recover CO{sub}2 from power plant flue gas, transport it to a reservoir site, inject it and recover and treat the resulting CBM for sale as natural gas. The model is constructed in an open, modular fashion, permitting changes and updates in any part of the process facilities without disturbance of the other modules. The model is intended to function as a screening tool to evaluate the relative merits of various combinations of power plant, injection gas composition, pipeline, producing field and produced gas composition. It is capable of scaling facility sizes and costs and calculating economic performance. To date, the model has been used to evaluate several related opportunities in CO{sub}2 sequestration using different CO{sub}2 sources. This paper outlines the model's internal workings and discusses in qualitative terms the results it has generated so far.
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