Transboundary CCS plays a key role in decarbonization strategies for Asian countries with a significant number of industrial emitters but limited domestic storage.
Transboundary CCS plays a key role in decarbonization strategies for countries with a significant number of industrial emitters but limited domestic storage. In Asia, transboundary CCS provides a safe storage solution, as it extends storage outside of the “Ring of Fire,” a geographic zone characterized by earthquake epicenters, volcanoes, and tectonic plate boundaries.
However, transporting CO2 can pose challenges related to phase change. At the recent International Conference on Transboundary CCS in Korea, Kian Wei Tan, senior advisor, Low Carbon Solutions, took the stage to discuss how pipeline design helps overcome challenges associated with CO2 quality.
Transboundary CCS includes many moving parts: emitters, shipping and pipeline transporters, and CO2 storage operators. “Non-standardized CO2 phase and quality will raise safety and system integrity concerns,” said Tan.
By the time CO2 reaches transport, operators have compressed CO2 into a supercritical or dense phase for efficiency and economic reasons. While in transit, transporters and operators must maintain a minimum pressure of 9.6Mpa or 96 bar to prevent phase changes
However, phase changes can occur when pressure surges or drops during transport. This can pose challenges such as pipeline blockage and flow issues caused by sudden phase changes. It can also result in inaccurate flow measurement rates, which leads to inaccurate audits and affects the certification process. Temperature changes during transport require operators to reheat and recompress CO2, which affects project economics. The presentation zeroed in on pipeline design to mitigate phase changes and help ensure CO2 quality throughout transport.
Pipeline design helps foster CO2 phase stability
U.S. operators already know about the importance of managing CO2 pipelines, quality, and flow. Regulations introduced in 1992 added CO2 to pipeline safety rules and created a definition of CO2. Given U.S. regulations and standards from projects such as Northern Lights, operators have a solid framework for their own pipeline design and management.
Material choice, pipe size, pressure control systems, and pipeline monitoring systems all help manage CO2 phase during transport. The choice of carbon steel and corrosion-resistant alloys preserves overall pipeline integrity, while pipe size determines flow rates. Pressure control systems, part of pipeline and process systems, help manage CO2 phases through pressure boosting to maintain optimal pressure. Pipeline monitoring systems detect leaks and potential pipeline integrity issues, which helps operators prevent phase changes.
In addition, pipeline integrity requirements help avoid introducing impurities into the CO2, such as water, nitrogen, oxygen, sulfite gases, or nitrite gases. N2 gas or advanced vacuum drying during pre-commissioning fully dehydrates the pipeline to assist with preventing impurities and improve flow assurance.
However, operators often overlook flange management, a critical component of pipeline integrity. Operators must maintain the integrity of every part of the pipeline, including joints. In pipeline and process systems, software can audit and monitor the age of each joint to alert operators to potential issues.
While transboundary CCS provides a solution for countries that need more space to store emissions, operators must prioritize pipeline design and management to ensure stable CO2 transport and address phase changes. Regulatory frameworks and advanced technologies can help maintain pipeline integrity for the journey.
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