GHGT-16 Panel Discussion 5C: CO2 impurities and implications for multiple source networks and hubs


By Abdul'Aziz Aliyu

3 November 2022

The 5th Panel discussion (panellists pictured below) entitled ‘CO2 Impurities for Multiple Source Networks and Hubs’ took place on the 25th of October 2022 at the 16th Greenhouse Gas Control Technologies Conference. The Panel was chaired by Haroun Mahgerefteh, University College London.

The panellists, their affiliation and the respective title of their presentations were as follows:

  1. Richard Porter – University College London; Opportunities and challenges of achieving European CO2 transport specifications
  2. Simon Roussanaly – SINTEF; Impact of impurities in tanked-based transport of CO2
  3. Heike Rutters – Bundesanstalt fur Geowissenschaften und Rohstoffe (BRG); Impacts of impurities on the storage infrastructure /site
  4. Filip Neele – TNO; Techno-economic trade-offs for CO2 impurities in CCUS chain integration

CCUS cluster networks is a novel way to advance industrial decarbonization. However, multiple CO2 emissions from industries such as the iron and steel, cement, chemical and refining, in addition to those of the power sector, will bring together gaseous streams with different CO2 concentrations and various impurities that will make them differ in their physical and chemical properties. Impurities in the CO2 stream have the potential to affect the efficiency and safety of transport system and storage solutions. Accurate monitoring of CO2 stream composition and metering in a transport network will therefore be critical for optimised safe and robust operation. The panel discussion gave an update of CO2 stream impurities issues for operators, regulators, and researchers, based on the experience of various pilot and industrial scale CCUS projects. 

5th Panel discussion: CO2 impurities and implications for multiple source networks and hubs

Richard Porter in his panel presentation sought to answer the big question: what is the optimum range and concentration of impurities that can be tolerated in the CO2 stream to enable its safe transport and storage at minimum cost? It is worth noting that there are significant differences in the CO2 storage specifications depending on the project. Pipeline transport and storage of CO2 with relatively high concentrations of some impurities are technically feasible as demonstrated by the North American EOR experience. Notwithstanding, there is a need to perform whole chain integration techno-economic analysis and optimisation (i.e., cost of purification vs cost of using more corrosion resistant material.

Simon Roussanaly presented on CO2 impurities in the context of transport of CO2 via ship and he presented the CO2 specifications for the delivery to the Northern Lights infrastructure (presented in the table below). The Northern Lights CO2 stream specification has raised questions, especially from CO2 source and capture side.These specifications might be too stringent and may likely increase the cost of CO2 capture and conditioning significantly. 

Table: CO2 specifications for the delivery to the Northern Lights facilities presented at the Panel Discussion 5C.

Component Concentration, ppm (mol basis) Water, H20 ≤ 30 Oxygen, O2 ≤ 10Sulfur oxides, SOX≤ 10Nitric oxide/Nitrogen dioxide, NOx≤ 10Hydrogen sulfide, H2S≤ 9 Carbon monoxide, CO≤ 100 Amine≤ 10Ammonia, NH3≤ 10Hydrogen, H2≤ 50 Formaldehyde≤ 20Acetaldehyde≤ 20Mercury, Hg ≤0.03Cadmium, Cd  ≤0.03

For different industries to agree on an optimal specification(s) is challenging because:

  • Impurities are industry, CO2 capture technology and even case-specific
  • It depends on the elements considered in the chain
  • Impurity removal cost depends on the type of impurities, levels, and specifications
  • Many technical aspects matter (corrosion, energy, safety during abnormal operation, etc., along the whole chain).
  • Potential synergy effects between impurities bring further complexity.

Simon Roussanaly concluded that there may be room to relax the current specifications for shipping of CO2 and this may depend on the final shipping pressure selected and it might be wise to focus on impurities that have a strong cost reduction potential.

Heike Rutters presented on CO2 stream composition in storage reservoirs and focussed on two discussion points and i.e.,

  • i.Composition of CO2 stream for injection
  • ii.Behaviour and fate of impurities in storage reservoirs.

This interactive session further raised questions during the panel discussion as to what are the compositions of the CO2 streams actually transported and how much variability of CO2 stream composition is acceptable. For more information regarding these points of discussion, you can visit the IEAGHG website for the following reports:

Filip Neele also contributed to the panel discussion regarding CO2 specification and pointed out that interoperability is a key issue and compositions used by early projects should not be too strict (or, open for future definition). Secondly, composition variations have an impact on conditions in transport and storage systems. Therefore, this should be taken into account in T&S network management and changes in phase behaviour should be included in storage site monitoring as well.

In a nutshell, this panel discussion has reaffirmed the significance of the broad spectrum of pollutants in CO2 streams converged in CCUS clusters emanating from different industrial processes and which poses a huge challenge to managing and standardizing CO2 stream specifications for transport and storage. This underscores the critical need for industries to work in tandem and come up with practical solutions to address the variations in the specifications of CO2 streams (emanating from different industrial projects) for transport (via ships and pipelines) and geological storage.