Effects of CO2-stream impurities on CO2 transport and storage

Expected Outcome:The design and safe operation of a CO2 transport and storage system represents specific challenges as it involves CO2 streams at different flow rates, pressures and states (liquid, gaseous, super critical, dissolved in water), and with different compositions and impurities. The presence of impurities will change the chemical and thermophysical properties with respect to a pure CO2 fluid. When CO2 is transported in pipelines at conditions close to its critical temperature and pressure, the impact of impurities on the thermophysical properties can become substantial. High levels of CO2 stream purity must be achieved to avoid two-phase flow during pipeline transportation. In addition, reactive impurities can form strong acids giving unacceptable corrosion of pipelines, tubings and ships, and can impact on injectivity, well integrity and seal integrity of geological storage sites. Directive 2009/31/EC regulates that CO2 streams, while they may contain incidental associated substances from the source, capture or injection process, the concentrations of these substances should be below levels that would adversely affect the integrity of the storage site or the relevant transport infrastructure and not pose a significant risk to the environment or human health. Member States should ensure that storage site operators only accept and inject CO2 streams if a risk assessment shows that these conditions are met.

The Communication on Industrial Carbon Management[1] underlines the need for pre-normative research on the physical and chemical behaviour of impure CO2 in order to contribute to relevant guidelines and standardisation work. This was also emphasised in a report prepared by a stakeholder group on CO2 standards under the CCUS Forum[2].

Project results are expected to contribute to all of the following expected outcomes:

• Contribution to an accurate understanding of the effects of impure (and possibly corrosive) CO2 flows along the transport network (in particular pipelines and shipping) or in the storage complex in line with Art. 12 of Directive 2009/31/EC, including any engineered or geological barriers to leakage in the near-well region;
• Inform relevant guidelines and contribute to standardisation work through improved understanding of the physical and chemical behaviour of impure CO2.

Scope:Based on the application chosen (either transport or storage), projects have to deliver:

• Recommendations for design and operation of pipelines and/or ship offloading, including recommendations for public health and safety requirements and for protective and/or mitigating material and/or approaches and/or monitoring technology to avoid adverse effects on the integrity of the relevant transport infrastructure caused by impurities;
• Recommendations for public health and safety requirements and for protective and/or mitigating material and/or approaches and/or monitoring technology to avoid adverse effects on the integrity of the storage complex;
• Guidance and recommendations for technology providers, regulatory authorities, certification and standardisation bodies, and define and implement ambitious dissemination actions to promote the project results and support their uptake.

Projects can address, for example, the following issues:

• Transient flow modelling along the pipeline network and;
• Combined thermodynamic and corrosion modelling to predict corrosion rates under different conditions;
• Reactive transport and geochemical modelling of the storage reservoir in the near-well zone, including associated geological barriers to leakage;
• Generation of experimental data on the geochemical reactions of reservoir rocks, caprocks, well cements and fault seals exposed to impure CO2 under the span of pressure and temperature regimes relevant for planned and future storage projects in saline aquifers, depleted hydrocarbon reservoirs and or mafic and ultra mafic formations for mineral storage of CO2, to tune existing and/or new models;
• Generation of experimental data on thermophysical and corrosive properties of CO2-rich mixtures under CCS-relevant conditions, to tune existing or new models;
• Impact of impurities on various equipment (e.g., valves, gaskets, compressors, instrumentation), in particular on non-metallic components in the CO2 transportation system;
• Impact of impurities on the physical behaviour and geochemical interaction of the CO2 stream within the storage complex;
• Impact of achieving very low impurity levels on the relative costs of competing capture technologies and the trade-off with costs for CO2 transportation and geological storage;
• Development of a systematic method to understand limits for impurities and define specifications for transport and storage infrastructure.

The use of the European Research Infrastructure for CO2 Capture, Utilisation, Transport and Storage ECCSEL is encouraged but not mandatory.

Selected projects are encouraged to seek synergy with possible standardisation activities performed by CEN, CENELEC, ISO and ETSI on pre-normative research for standards for the transport and permanent storage of carbon dioxide[3].

International cooperation is encouraged, in particular with projects or partners from the United States.

[1] EUR-Lex - 52024DC0062 - EN - EUR-Lex (europa.eu)

[2] https://circabc.europa.eu/ui/group/75b4ad48-262d-455d-997a-7d5b1f4cf69c/library/13c2a475-c705-432d-8ca3-17ce799ba502/details

[3] Open call for proposal, 6 June 2024. See: Support to Standardisation activities performed by CEN, CENELEC and ETSI - European Commission (europa.eu)