Task 2.1: CO2 pipeline integrity
Overall objective: To develop a coupled fluid-structure fracture propagation model to enable safe and cost-effective design and operation of CO2 pipelines.
CO2 Pipeline integrity and its importance for CCS
Most large-scale implementations of CCS will require CO2 to be transported as dense phase in a pipeline. Parts of this CO2 transportation will in some situations interfere and be visible from areas with public access. For public acceptance of CCS, it is therefore of great importance that such pipelines are considered not to pose a threat to public safety.
A particular challenge for pipeline transport of CO2 in dense phase (compared to e.g. natural gas), is the risk of long running fractures in the pipeline. Due to the two-phase behaviour of CO2 during decompression from dense phase — e.g. as a result of a rupture caused by third party impact — a high CO2 saturation pressure might cause a fracture to propagate for a long distance unless the pipeline material has sufficient fracture resistance. Though there is a DNV recommended practice (RP-J202) on design and operation of CO2 pipelines, there are today no established methods, standards or tools to assess and predict the behaviour of running fractures in CO2pipelines. It is the aim of Task 2.1 to provide a numerical tool and method that can be used to provide safe and cost-effective design and operation of CO2 pipelines.
Contribution to the overall objectives of BIGCCS
The International Energy Agency’s two-degree scenario is one realistic way of limiting the global warming to 2 °C. In this scenario, CCS accounts for about 1/5 of the CO2-emission reduction in 2050, corresponding to seven billion metric tonnes per year.
Fracture propagation control (FCP), that is, the estimation of risk of long running fractures, is of great importance in design and operation of high pressure pipelines. For natural gas and hydrogen pipelines, FCP is well handled by existing (empirical) methods. However, there is limited worldwide experience in design and operation of CO2 pipelines. Mainly due to the two-phase behaviour of CO2 during decompression from dense phase, today’s FPC methods yields non-conservative estimates of the required pipeline properties. An important element in reducing cost, while maintaining the highest safety, is to understand how long running fractures in the CO2 pipelines can be avoided. This is what we aim for in BIGCCS Task 2.1.
Task 2.1 achievements thus far
- A coupled fluid-structure fracture propagation-control model has been developed, and it has been verified using data from hydrogen and methane crack-arrest experiments.
- The coupled fluid-structure model has been extended to account for CO2 properties, including the formation of solid CO2.
- Five journal articles and three conference articles have been published
- One PhD has been completed.
If you want to know more
- Particular challenges with operation and design of CO2 pipelines
- Details on the BIGCCS coupled code
- CO2 mixtures and their effect on FCP
Some of the the work performed in this task on thermo- and fluid dynamics builds upon results from the CO2 Dynamics project. Task 2.1 involves cooperation between SINTEF Energy Research, SINTEF Materials and Chemistry and NTNU.