Building Safe CO2 Transport Infrastructure: The Cornerstone of CCUS

Abstract

Abstract This paper captures key aspects for design of CO2 transport pipelines and aims to make these available to project developers, decision makers and regulators working on CO2 transport projects. Currently the regulations and standards used for CO2 pipelines mainly originate in natural gas pipeline codes. Hazards, risks, and design practices for natural gas presently serve as a compass in CO2 risk assessment. It is true that the closest experience for dense phase CO2 transport is natural gas. However, there are stark differences between the two fluids. These differences are mainly due to the thermophysical properties of dense phase CO2. Using the existing models to predict properties such as the solubility limit of water in a CO2 stream may lead to inaccurate results for industrially captured CO2 which often carries a range of impurities. The correct prediction of water solubility in CO2 streams (both gas and dense phase) is vital since water drop out can lead to corrosion failure in steel pipelines in presence of impurities. This paper shows the extent of general corrosion in CO2 pipes in presence of acidic impurities that lead to low pH levels. Based on the findings, it is concluded that pipeline operators must eliminate the risk of aqueous phase water formation in the pipe by using appropriate and sufficiently designed dehydration processes. The risk of residual water through the startup phase and formation of water through transient operations (caused by CO2 phase change) must also be carefully considered in the design.