In a recent publication, Ehlig-Economides & Economides (2010) have sought to demonstrate that carbon dioxide capture and storage (CCS) is not technically or economically feasible, based on a supposed lack of underground storage capacity. We consider this to be a serious misrepresentation of the scientific, engineering and operational facts surrounding CCS. Ehlig-Economides & Economides raise a number of storage related issues: reservoir boundaries, capacity, pressure management, storage integrity, dissolution and storage in depleted reservoirs. We take each one in turn, highlighting specific errors in the paper but also drawing attention to more general background issues. Finally, we discuss in more detail some inconsistencies in the paper surrounding the reservoir engineering calculations.

This paper reports results from an initial benchmarking study of the Timmins Process, a novel pre-combustion carbon capture process that uses a combination of traditional unit operations, DEPG scrubbing, carbon monoxide shift and carbon dioxide liquefaction, in a unique arrangement. The study examines the performance of the Timmins Process embedded within an integrated gasifier combined cycle (IGCC) flowsheet and the results are compared to data from the US Department of Energy (DoE) cost and performance baseline studies for coal-fired energy plants. Modeling was undertaken using UniSim R400 (Honeywell Inc.) with thermodynamic parameters for DEPG interactions being regressed from literature data; these results are also reported here. The net efficiency of an IGCC flowsheet incorporating the Timmins Process, with a carbon capture level of 91.8 % on a mass basis, varies between 33.8 % and 34.3 % depending on the process configuration and the cooling water temperature. This result compares very favorably to a DoE study for a conventional capture process embedded within an IGCC flowsheet that operated at an efficiency of 31.2 %. Further, more detailed, studies are recommended to assess the impact of various assumptions that underpin this work.

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