ABSTRACT

Carbon dioxide (CO2) is the primary notorious greenhouse gas which is being increasingly emitted to our ecosystem as a result of various human activities. Carbon capture and storage (CCS) is the most promising technology available today for utilizing fossil fuels as reliable energy resources while significantly reducing CO2 emissions and protecting the climate. Pipeline transportation is recognized as the most cost-effective and relatively safe solution in the context of CCS, as it can transport large amounts of CO2 under predetermined and controlled conditions. Depending on CO2 sources and applied capture/separation technologies, however, the transported sc-CO2 stream always contains some aggressive impurities that could lead to extensive corrosion of pipe steels as well as cracking. The effects of impurities on corrosion are far from clear because of very limited field experience, scarce laboratory corrosion data and somewhat conflicting published results. This paper re-examines most public and in-house corrosion data on the effects of six typical impurities to advance the fundamental understanding of how pipeline steels corrode in sc-CO2 environments and identify knowledge gaps for further investigations. It is anticipated to advance the commercial deployment of CCS technology in a cost-effective manner.

INTRODUCTION

Today the combustion of fossil fuels is still the primary energy production technology in which a huge amount of CO2 gas is inevitably generated in flue gas waste and then emitted into the atmosphere, leading to serious negative impacts on global climate change. According to recent International Energy Agency (IEA) report, about 10 gillion tons of CO2 shall be reduced to meet the needs of sustainable economic growth and ecological development by 2050.1 Carbon capture and storage (CCS) technology has been developed as one of the promising methods to control CO2 emissions by capturing most CO2 gas produced at fossil fuel fired plants and sending to specific sites for either permanent storage or CO2 utilization (such as enhanced oil recovery, waste mining tailing discharge, and the conversion of CO2 into syngas as raw chemical materials etc.).2, 3 In a typical CCS system, CO2 transportation is a critical component in which the captured CO2 stream must be safely delivered to the designed locations for further treatments. To avoid the formation of two phases during transportation and remarkably increase the transportation efficiency with low cost, the captured CO2 streams are usually compressed into supercritical state (named as supercritical CO2, sc-CO2) before the long-distance transportation in pipelines.

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