The ultimate composition of the CO2 stream captured from fossil fuel power plants or other CO2 intensive industries and transported to a storage site using high pressure pipelines will be governed by safety, environmental and economic considerations.

So far, most of the studies performed on this topic have been limited in scope, primarily focusing on investigating the impact of the CO2 stream impurities on each part of the Carbon Capture and Sequestration (CCS) chain in isolation. This is a significant drawback given the markedly different sensitivities of the pipeline, well bore materials and storage sites to the various impurities.

For example, trace elements such as Lead, Mercury and Arsenic in the CO2 stream are of far greater concern in an aquifer storage site than compared to the pipeline given the risk of water table contamination. On the other hand, even small concentrations of water in the CO2 stream are detrimental to the pipeline due to corrosion, but of benefit even at high concentrations during storage given the immobilisation effect of water on CO2.

‘What is good for the pipeline is not necessarily good for storage’

“It is clear that the optimum composition and concentration of the impurities in the captured CO2 stream involves a delicate balance between the different requirements within the CCS chain, spanning capture, transportation and storage, with cost and safety implications being the over-arching factor. Pivotal to these considerations is an understanding of the impact of the impurities on the physico-chemical properties of CO2 and its hazard profile.”

‘Despite all this, the EC has no standards specific to CO2 pipelines’

Key Objectives

i. Establish the typical range and concentration of the CO2 stream impurities based upon the three main capture technologies including pre-combustion, post-combustion and oxyfuel technologies by reference to published literature and direct analysis of gas flue samples.

ii. Use experimentation and theoretical modelling to develop accurate, robust and efficient physical property models based on SAFT Equation of State (EoS) for gas and dense phase CO2 mixtures containing the typical impurities at the operating temperatures and pressures encompassing the entire CCS chain.

iii. Model non-isothermal steady state flows in pressurised pipelines transporting COcontaining the typical impurities using the EoS developed in (ii), followed by its application to realistic pipeline network systems in order to identify the type of impurities that have the most adverse impact on CO2 pipeline pressure drop, capacity, fluid phase and compressor power requirements.

iv. Model the impact of impurities, using the EoS from (ii), on the near-field structure of accidental releases, and the impact this has on their dispersion characteristics, with validation against data gathered as part of the project. Additionally, provide detailed pipe wall and crack-flow interaction predictions for input into (v).

v. Develop and validate fluid/structure fracture models for ductile and brittle fracture propagation in CO2 pipelines. Apply these models, based on various candidate pipeline steels, to identify the type of impurities and operating conditions that have the most adverse impact on a pipeline’s resistance to withstanding long running fractures.

vi. Using experimentation, identify CO2 mixtures that have the most pronounced impact on the corrosion behaviour of pipe and well bore candidate steels and develop appropriate corrosion prevention measures.

vii. Quantify the effect of impurities on the performance of CO2 geological storage, both in terms of fluid/rock interactions and leakage of trace elements through a combination of modelling studies, laboratory experiments and large-scale field injection experiments using CO2 and CO2 mixtures.

viii. Design a decision making risk assessment tool for determining the additional safety and environmental impacts associated with the presence of impurities during COtransportation and storage followed by its application for recommending appropriate prevention and mitigation measures.

ix. Develop a model-based approach for assessment of the impact of impurities in the CO stream on the CCS system performance, and use this approach to explore feasible operational envelopes.

x. Undertake a cost-benefit analysis of the whole system, based on the above findings, exploring appropriate levels of purity from a whole system perspective and recommend mixing protocols.

  • WP 1

    Objectives

    Fluid Properties and Phase Behaviour (Led by NCSR)
    Work Package 1.1 – Typical Impurities

    1. Define the range and level of impurities expected in CO2 product gas streams from different capture technologies and other CO2intensive industries for use as the basis of investigations in the rest of the WPs.
    2. Perform a cost analysis for modifying the range and level of impurities based on the transportation and storage requirements identified by the rest of the project partners. i.e. to understand the cost implications on capture when increased purity is required.

    Work Package 1.2 – Equation of State Development and Validation

    1. Develop new SAFT based models for CO2 mixtures with typical impurities applicable to solid-phase CO2 (dry ice) and electrolytic solutions (water + brine).
    2. Extend recently developed SAFT EoS for CO2 mixtures applicable to transportation conditions to additional impurities and CCS capture and storage conditions using experimental data generated from WP1.1 and WP1.3.
    3. Provide physical properties to WP2, WP3 and WP4 through an integrated software package framework.

    Work Package 1.3 – Experimental Evaluation

    1. Identify the gaps in current knowledge, and guide the experimental programme for physical properties measurements of CO2 mixtures with impurities at CCS conditions.
    2. Perform experiments to generate VLE data for the binary, ternary and multi-component mixtures of CO2 with impurities.
    3. Perform experiments to generate data on the transportation properties of CO2 with impurities.
    4. Use the experimental data to support the development and validation of the EoS in WP1.2.
  • WP 2

    Objectives

    CO2 Storage Reservoir Performance (Led by UU)
    The overall and common goal of the closely interacting work packages WP3.1 and WP3.2 is to obtain an understanding of the effects of impurities on the performance of the geological storage operation, in terms of fluid/rock interactions and leakage of trace elements by means of:

    1. A unique field injection test of water and of super-critical CO2 (with and without impurities), to be conducted at the experimental site of Heletz (Israel);
    2. Conducting laboratory experiments aimed at determining the impact of the impurities on the mechanical properties of the reservoir and the caprock;
    3. Integrate the results of the laboratory experiments conducted in the frame of the COORAL project, coordinated by partner BGR and funded by the German Federal Ministry of Economics and Technology (BMWi).

    This will be a notable advancement of the state-of-the-art, and the focus of WP3.2 is to use this data alongside that generated from multiple other sources in the work package to support extensive model development and model application to enhance the understanding of CO2geological storage performance in the presence of impurities. The investigation of a potential CO2 leakage will involve the injection of industrial grade CO2 into a shallow water aquifer in France, followed by the monitoring the injected fluid, its trace impurities, and the potential mobilisation of metallic trace elements from the rock.

    Work Package 3.1 – Experimental Evaluation of Impurities Effects on Storage Properties

    1. Laboratory and field scale investigation of the impact of impurities in the CO2 stream on (i) rock properties and (ii) CO2 spreading and trapping behaviour, and the subsequent effects on storage performance.
    2. Provide unique datasets of field data for model validation.
    3. Investigate the impact on freshwater aquifers due to possible leakage of trace elements from injected CO2 stream and recommend appropriate leakage monitoring methods for such overlying aquifers and at the ground surface.

    Work Package 3.2 – Modelling of the Impurities on Geological Storage
    The objective of WP3.2 is to develop the theoretical understanding of physical and chemical processes involving impure CO2 in geological storage, and validate these by embedding them within numerical models for simulating CO2 spreading and trapping and the related coupled thermal-hydrological-mechanical-chemical (THMC) processes. In particular:

    1. Through analysis of laboratory data and data from the field experiment of CO2 injection (WP3.1), in addition to theoretical considerations, improve the relevant process and parametric models to account for the effect of impurities in the CO2 stream;
    2. Based on the findings in 1, improve and further develop the existing simulation models;
    3. Validate these models against existing field and laboratory data. In particular, against data of the field injection experiment with impure CO2;
    4. Through model application to a wider range and larger scale of field scenarios, obtain an understanding of the relevant effects of impurities on storage performance.
  • WP 3

    Objectives

    Project Management (UCL)
    Manage and coordinate the project’s technical and administrative activities to ensure its success via the fulfilment of the following tasks:

    1. Establishing the project management structure.
    2. Communication and reporting to the EC representatives.
    3. Communication with the Strategic Advisory Board.
    4. Effective coordination and harmonisation of consortium activities.
    5. Review and evaluation of project progress reports milestones.
    6. Quality control of deliverables before publication.
    7. Implementation of the mechanisms for effective communication between partners.
    8. Problems resolution.
    9. Production of validation test protocols.
    10. Risk assessment of the high pressure test facility in China and the production of operational safety manual.
    11. Monitoring of the implementation of the EC ethical requirements by the project partners regarding project related safety and environmental issues.

    Work Package 7.1 – Management Structure

    Work Package 7.2 – Communication and reporting to the EC representatives

    Work Package 7.3 – Production of the validation test protocol

    Work Package 7.4 – Risk Assessment of production of safety operational manual for the high pressure pipeline tests in China

    Work Package 7.5 – Quality control and project progress reporting

    Work Package 7.6 – Communication and dataflow between partners

    Work Package 7.7 – Unforeseen events and resolutions

    Work Package 7.8 – Monitoring of the implementation of the EC ethical requirements by the project partners regarding project related safety and environmental issues

  • WP 4

    Objectives

    CO2 Transport (Led by UCL)
    Work Package 2.1 – Pressure Drop/Compressor Requirement

    1. Model non-isothermal steady-state flow for pressure drop (and hence compressor power requirements) in pipeline networks transporting CO2 with typical stream impurities using the dedicated EoS developed under WP1.
    2. Develop compression strategies for minimising compressor power requirements.
    3. Perform parametric studies using the flow model developed under (1) to identify the type and composition of stream impurities that have the most adverse impact on the CO2 pipeline pressure drop, pipeline capacity, fluid phase and compressor power requirements.

    Work Package 2.2 – Near-Field Dispersion

    1. To develop (UoL) a computational fluid dynamic (CFD) model capable of predicting the near-field structure of high pressure releases of supercritical, dense phase and gaseous CO2 containing impurities typical of those to be encountered in an integrated CCS chain, including an equation of state that covers CO2 with impurities (NCSR) and models for the formation of liquid droplets and solid particles.
    2. To conduct (INERIS) controlled small and medium-scale experiments involving high pressure releases of CO2 with a range of impurities, with near-field measurements of the dispersing jets and pipe-surface temperatures in the vicinity of punctures representative of typical geometries.
    3. To conduct (DUT) controlled large-scale experiments involving high pressure releases of CO2 with a range of impurities, with near-field measurements of the dispersing jets, and temperature measurements in the vicinity of a pre-designed crack geometry.
    4. To validate (UoL) the CFD model derived against experimental data available in the literature, and to be generated as part of the project as above.
    5. To demonstrate (UoL and INERIS) the usefulness of the CFD model developed by interfacing its predictions for a number of realistic release scenarios with existing far-field dispersion models in order to predict hazards at large distances for use in risk assessments.

    Work Package 2.3.1 – Ductile Fractures

    1. Develop a computationally efficient CFD based fluid/structure fracture model for predicting ductile fracture propagation behaviour in gas and dense phase CO2 pipelines made from proposed candidate steels transporting typical stream impurities.
    2. Conduct sensitivity analyses using the validated fracture model developed under (1, WP2.3.2) to identify the type and composition of stream impurities that have the most pronounced impact on ductile facture propagation behaviour in CO2 pipelines.
    3. Conduct experiments using the fully instrumented CO2 pipeline test facility constructed in China as part of the EC FP7 CO2PipeHaz to validate:
      1. the fracture model developed under (1, WP2.3.1) above based on shock tube experiments,
      2. the outflow model based on pipeline puncture and rupture experiments.

    Work Package 2.3.2 – Brittle Fractures

    1. Develop and validate a fluid/structure fracture model for brittle fracture propagation in CO2 pipelines made from the proposed candidate steels transporting typical stream impurities. The fracture toughness and crack propagation data of the steel grades will be determined experimentally.
    2. Identify the type of impurities and operating conditions that have the most adverse impact on a pipeline’s resistance to withstanding long-running fractures for various pipeline steel types.
    3. Conduct prolonged release experiments using the same fully instrumented pipeline test facility as used in WP2.3.1 to validate the model.
  • WP 5

    Objectives

    CO2 Transport (Led by UCL)
    Work Package 2.1 – Pressure Drop/Compressor Requirement

    1. Model non-isothermal steady-state flow for pressure drop (and hence compressor power requirements) in pipeline networks transporting CO2 with typical stream impurities using the dedicated EoS developed under WP1.
    2. Develop compression strategies for minimising compressor power requirements.
    3. Perform parametric studies using the flow model developed under (1) to identify the type and composition of stream impurities that have the most adverse impact on the CO2 pipeline pressure drop, pipeline capacity, fluid phase and compressor power requirements.

    Work Package 2.2 – Near-Field Dispersion

    1. To develop (UoL) a computational fluid dynamic (CFD) model capable of predicting the near-field structure of high pressure releases of supercritical, dense phase and gaseous CO2 containing impurities typical of those to be encountered in an integrated CCS chain, including an equation of state that covers CO2 with impurities (NCSR) and models for the formation of liquid droplets and solid particles.
    2. To conduct (INERIS) controlled small and medium-scale experiments involving high pressure releases of CO2 with a range of impurities, with near-field measurements of the dispersing jets and pipe-surface temperatures in the vicinity of punctures representative of typical geometries.
    3. To conduct (DUT) controlled large-scale experiments involving high pressure releases of CO2 with a range of impurities, with near-field measurements of the dispersing jets, and temperature measurements in the vicinity of a pre-designed crack geometry.
    4. To validate (UoL) the CFD model derived against experimental data available in the literature, and to be generated as part of the project as above.
    5. To demonstrate (UoL and INERIS) the usefulness of the CFD model developed by interfacing its predictions for a number of realistic release scenarios with existing far-field dispersion models in order to predict hazards at large distances for use in risk assessments.

    Work Package 2.3.1 – Ductile Fractures

    1. Develop a computationally efficient CFD based fluid/structure fracture model for predicting ductile fracture propagation behaviour in gas and dense phase CO2 pipelines made from proposed candidate steels transporting typical stream impurities.
    2. Conduct sensitivity analyses using the validated fracture model developed under (1, WP2.3.2) to identify the type and composition of stream impurities that have the most pronounced impact on ductile facture propagation behaviour in CO2 pipelines.
    3. Conduct experiments using the fully instrumented CO2 pipeline test facility constructed in China as part of the EC FP7 CO2PipeHaz to validate:
      1. the fracture model developed under (1, WP2.3.1) above based on shock tube experiments,
      2. the outflow model based on pipeline puncture and rupture experiments.

    Work Package 2.3.2 – Brittle Fractures

    1. Develop and validate a fluid/structure fracture model for brittle fracture propagation in CO2 pipelines made from the proposed candidate steels transporting typical stream impurities. The fracture toughness and crack propagation data of the steel grades will be determined experimentally.
    2. Identify the type of impurities and operating conditions that have the most adverse impact on a pipeline’s resistance to withstanding long-running fractures for various pipeline steel types.
    3. Conduct prolonged release experiments using the same fully instrumented pipeline test facility as used in WP2.3.1 to validate the model.
  • WP 6

    Objectives

    CO2 Transport (Led by UCL)
    Work Package 2.1 – Pressure Drop/Compressor Requirement

    1. Model non-isothermal steady-state flow for pressure drop (and hence compressor power requirements) in pipeline networks transporting CO2 with typical stream impurities using the dedicated EoS developed under WP1.
    2. Develop compression strategies for minimising compressor power requirements.
    3. Perform parametric studies using the flow model developed under (1) to identify the type and composition of stream impurities that have the most adverse impact on the CO2 pipeline pressure drop, pipeline capacity, fluid phase and compressor power requirements.

    Work Package 2.2 – Near-Field Dispersion

    1. To develop (UoL) a computational fluid dynamic (CFD) model capable of predicting the near-field structure of high pressure releases of supercritical, dense phase and gaseous CO2 containing impurities typical of those to be encountered in an integrated CCS chain, including an equation of state that covers CO2 with impurities (NCSR) and models for the formation of liquid droplets and solid particles.
    2. To conduct (INERIS) controlled small and medium-scale experiments involving high pressure releases of CO2 with a range of impurities, with near-field measurements of the dispersing jets and pipe-surface temperatures in the vicinity of punctures representative of typical geometries.
    3. To conduct (DUT) controlled large-scale experiments involving high pressure releases of CO2 with a range of impurities, with near-field measurements of the dispersing jets, and temperature measurements in the vicinity of a pre-designed crack geometry.
    4. To validate (UoL) the CFD model derived against experimental data available in the literature, and to be generated as part of the project as above.
    5. To demonstrate (UoL and INERIS) the usefulness of the CFD model developed by interfacing its predictions for a number of realistic release scenarios with existing far-field dispersion models in order to predict hazards at large distances for use in risk assessments.

    Work Package 2.3.1 – Ductile Fractures

    1. Develop a computationally efficient CFD based fluid/structure fracture model for predicting ductile fracture propagation behaviour in gas and dense phase CO2 pipelines made from proposed candidate steels transporting typical stream impurities.
    2. Conduct sensitivity analyses using the validated fracture model developed under (1, WP2.3.2) to identify the type and composition of stream impurities that have the most pronounced impact on ductile facture propagation behaviour in CO2 pipelines.
    3. Conduct experiments using the fully instrumented CO2 pipeline test facility constructed in China as part of the EC FP7 CO2PipeHaz to validate:
      1. the fracture model developed under (1, WP2.3.1) above based on shock tube experiments,
      2. the outflow model based on pipeline puncture and rupture experiments.

    Work Package 2.3.2 – Brittle Fractures

    1. Develop and validate a fluid/structure fracture model for brittle fracture propagation in CO2 pipelines made from the proposed candidate steels transporting typical stream impurities. The fracture toughness and crack propagation data of the steel grades will be determined experimentally.
    2. Identify the type of impurities and operating conditions that have the most adverse impact on a pipeline’s resistance to withstanding long-running fractures for various pipeline steel types.
    3. Conduct prolonged release experiments using the same fully instrumented pipeline test facility as used in WP2.3.1 to validate the model.
  • WP 7

    Objectives

    CO2 Transport (Led by UCL)
    Work Package 2.1 – Pressure Drop/Compressor Requirement

    1. Model non-isothermal steady-state flow for pressure drop (and hence compressor power requirements) in pipeline networks transporting CO2 with typical stream impurities using the dedicated EoS developed under WP1.
    2. Develop compression strategies for minimising compressor power requirements.
    3. Perform parametric studies using the flow model developed under (1) to identify the type and composition of stream impurities that have the most adverse impact on the CO2 pipeline pressure drop, pipeline capacity, fluid phase and compressor power requirements.

    Work Package 2.2 – Near-Field Dispersion

    1. To develop (UoL) a computational fluid dynamic (CFD) model capable of predicting the near-field structure of high pressure releases of supercritical, dense phase and gaseous CO2 containing impurities typical of those to be encountered in an integrated CCS chain, including an equation of state that covers CO2 with impurities (NCSR) and models for the formation of liquid droplets and solid particles.
    2. To conduct (INERIS) controlled small and medium-scale experiments involving high pressure releases of CO2 with a range of impurities, with near-field measurements of the dispersing jets and pipe-surface temperatures in the vicinity of punctures representative of typical geometries.
    3. To conduct (DUT) controlled large-scale experiments involving high pressure releases of CO2 with a range of impurities, with near-field measurements of the dispersing jets, and temperature measurements in the vicinity of a pre-designed crack geometry.
    4. To validate (UoL) the CFD model derived against experimental data available in the literature, and to be generated as part of the project as above.
    5. To demonstrate (UoL and INERIS) the usefulness of the CFD model developed by interfacing its predictions for a number of realistic release scenarios with existing far-field dispersion models in order to predict hazards at large distances for use in risk assessments.

    Work Package 2.3.1 – Ductile Fractures

    1. Develop a computationally efficient CFD based fluid/structure fracture model for predicting ductile fracture propagation behaviour in gas and dense phase CO2 pipelines made from proposed candidate steels transporting typical stream impurities.
    2. Conduct sensitivity analyses using the validated fracture model developed under (1, WP2.3.2) to identify the type and composition of stream impurities that have the most pronounced impact on ductile facture propagation behaviour in CO2 pipelines.
    3. Conduct experiments using the fully instrumented CO2 pipeline test facility constructed in China as part of the EC FP7 CO2PipeHaz to validate:
      1. the fracture model developed under (1, WP2.3.1) above based on shock tube experiments,
      2. the outflow model based on pipeline puncture and rupture experiments.

    Work Package 2.3.2 – Brittle Fractures

    1. Develop and validate a fluid/structure fracture model for brittle fracture propagation in CO2 pipelines made from the proposed candidate steels transporting typical stream impurities. The fracture toughness and crack propagation data of the steel grades will be determined experimentally.
    2. Identify the type of impurities and operating conditions that have the most adverse impact on a pipeline’s resistance to withstanding long-running fractures for various pipeline steel types.
    3. Conduct prolonged release experiments using the same fully instrumented pipeline test facility as used in WP2.3.1 to validate the model.

Aerial video recording of a CO2 pipeline rupture test

CO2 Pipeline Rupture Experiment

Infrared video recording of a CO2 pipeline puncture release1

CO2 Pipeline Safety