While the world focuses on carbon dioxide (CO2)—its problems and its uses—many are looking at how to move it around. Fortunately, a pipeline infrastructure already exists. Unfortunately, the pipelines were made for natural gas and not enough is known about how that infrastructure can handle CO2.
“The need to transport CO2 is expected to increase significantly in the years to come as part of the widespread view that carbon capture and storage (CCS) is a viable means to reduce CO2 emissions,” said Prajeev Rasiah, the executive vice president for energy systems, northern Europe, at DNV.
DNV and consulting firm Carbon Limits recently published “Re-Stream—Study on the Reuse of Oil and Gas Infrastructure for Hydrogen and CCS in Europe.” The report—commissioned by IOGP Europe, Concawe, The European Network of Transmission System Operators for Gas, and Gas Infrastructure Europe—provides data on the reuse of offshore and onshore oil and gas transmission pipelines. The report looks at relevant infrastructure and attempts to define which technical adaptations and investments would be required to unlock the potential for reuse for transporting CO2 and hydrogen.
Sixty-five pipeline operators participated in the study, providing data for approximately 58,000 km of pipelines. The study finds significant potential for reuse of the oil and gas transmission pipelines in Europe to transport CO2.
An initial technical screening was undertaken that considered the data provided by the pipeline operators. The criteria used for the initial screening are the construction materials and pipeline design characteristics, the internal pipeline condition, safety matters, age, and transport capacity.
Of the approximately 58,000 km of pipelines assessed in this project (41,700 km onshore and 16,300 km offshore), the screening revealed several technical points. First, the screening revealed no showstoppers for transporting CO2 in the gaseous phase in the existing onshore and offshore pipelines. Also, CO2 transport in a dense phase already is possible in more than half of the offshore pipelines, considering the current state of knowledge and standards. An additional 40% of the offshore length would require more testing, analyzing, or updating of standards to be reusable.
A very small portion of the onshore pipelines, however, were revealed to be reusable currently for CO2 transport in the dense phase. Approximately one-quarter of the onshore pipeline length appeared to be reusable, provided more detailed analyses revealed positive results.
DNV is teaming up with Wintershall Noordzee to conduct some of this more-detailed analysis. “Our calculations already show that existing offshore pipelines could be well suited for transporting liquid CO2,” said Klaus Langemann, Wintershall’s senior vice president of carbon management and hydrogen. Now, the two companies, along with OTH Regensburg University of Applied Sciences, are exploring how existing natural gas pipelines in the southern North Sea can be used safely for future CO2 transport.
The project aims to examine how having the pipeline submerged in water affects the capability to stop a running ductile fracture.
The work being done by DNV, Wintershall, and the university involves large-scale CO2 pipeline testing of running pipeline fracture under water and compares it with similar testing of the pipe in open air. The tests aim to quantify the potential benefits of the water surrounding the pipeline on the crack-arrest behavior for a specific pipeline and, thus, better define the model parameters used for different backfill types.
Further, preliminary simulation results using numerical models suggest that running fracture in pipelines transporting dense-phase CO2 may be arrested easier under water than in air.
“We are optimistic about the further investigations,” Langemann said. “The next step will be to demonstrate the reliability of the evaluation process and prove the feasibility experimentally.”
In addition to the analysis being conducted by DNV and Wintershall, the Net Zero Technology Centre, formerly the Oil and Gas Technology Centre, has released “A Methodology Aimed at Assessing the Suitability of a Pipeline for Repurposing To Transport a Different Fluid.” The method strongly considers the lifespan of a pipeline because repurposing generally means the pipeline will be in use longer than initially planned.
“At the core of the methodology,” the summary reads, “is a technical integrity assessment in two parts: The first reviews the period from design until present day to determine the current condition of the pipeline, and the second looks forward to determine when the end of life might occur.”
