Leveraging their background in industry and working on large carbon capture projects in the UK, Netherlands, Australia, and Canada, the authors examine the methodologies currently used to mitigate corrosion risks in supercritical CO2 streams saturated with impurities, highlighting areas of conservatism, and produce the next steps necessary to address the knowledge gap.
The authors will also propose work to address this gap, through an early-stage concept for a mesoscale experimental project which seeks to categorise the effect impurities have on supercritical CO2 transport. The project aims to reduce conservatism and allow greater uptake of carbon capture across industries.
Vital work is being carried out across engineering to ensure the net-zero commitments as laid out in the Paris agreement are met. Due to increased government investment, carbon capture, utilisation, and storage (CCUS) has become key to achieving these commitments, with some industries only able to decarbonise through CCUS, such as concrete or fertiliser production. Carbon capture has also moved away from vertically integrated systems, with single emitters having dedicated downstream transport and storage sites, to larger systems gathering CO2 with a shared transport and storage infrastructure. This allows smaller CO2 emitters the potential to tie into these capture networks and make use of the scale of the project. Although this gives greater savings by utilising economies of scale, it also introduces a considerable challenge to the network operator.
As highlighted in previous work1,2, it has been proven that dense phase CO2 when saturated with impurities poses a much higher corrosion risk than pure CO2. This clean CO2 has been extensively used in EOR in the US and the middle east, with little incident3. The formation of acids, and potentially liquids or solids, has led the industry to take strong stances on the composition of fluid allowed in transport pipelines. The impurities present will vary from project to project, but impurities such as NOx, SOx, and H2S, are likely to present as by-products of combustion, and could potentially lead to acid formation in the fluid stream, likewise, the presence of O2 and H2O will serve to create the conditions that allow CO2 corrosion or provide the conditions for reactants to form. These common impurities have so far been present in each fluid composition.