Regional carbon capture and storage hubs enable multiple CO2 emitters to share infrastructure and pipelines, thereby reducing costs. Advanced automation solutions can increase the operational efficiency and enhance the economic viability of these projects.
Regional carbon capture and storage (CCS) hubs can be an economically attractive proposition, as they enable multiple emitters of CO2 in an area – such as power stations, chemical plants and steel works – to share infrastructure and pipelines. Even so, CCS still involves significant costs, as capturing and compressing CO2 is highly energy-intensive. It is therefore vital to optimize the efficiency of the process and reduce costs. In a Carbon Capture Journal article, ‘Increasing the Viability of CCS Hubs’, I detail some of the advanced automation technologies, engineering tools and software solutions that can help to achieve these targets.
The article explains that post-combustion amine-based absorption is the most mature carbon capture process. It consists of an absorber unit, where a chemical solvent captures CO2 from flue gas, and a stripper, where the chemical solvent is regenerated and the CO2 is extracted. The efficiency of the process depends on the solvent circulation rate. There is a trade-off between carbon capture efficiency and the cost of the energy required to regenerate the solvent, so the challenge is to achieve the target CO2 capture rate in the most efficient manner. The article states:
…Monitoring the capture percentage with online analysis allows for process optimisation through multivariable control and analytics. Automating the lean amine concentration measurement with Coriolis mass flow and density meters enables the solvent circulation rate to be accurately determined, so that the desired capture efficiency can be achieved at the lowest cost.
I then explain that once CO2 has been removed from the source, it is then usually liquefied under compression at low temperature and pumped through a pipeline to be stored underground or used in other chemical processes downstream. The efficiency of the liquefaction process depends on reliable measurement and control. The article continues:
…Control systems offering seamless integration of plant visualisation tools help to maintain full asset visibility, while smart wireless networks reduce installation costs and enable continuous monitoring to ensure a fast response to any issues that might occur.
To keep the CO2 stable in its liquid phase for long distance transport, it must be kept under constant pressure, which requires compressors at various stages along the pipelines. It is important to maximize compressor availability, as unexpected failures can result in capacity outage, equipment damage, excessive maintenance, increased costs and scheduling delays. I explain that:
…Anti-surge control valves and optimised digital valve solutions ensure stable flow to the compressor, preventing damage and increasing compressor life, while appropriate pressure safety valves enable operation nearer to optimal pressure setpoints and reduce fugitive emissions. Pervasive sensing technologies and data analytics are also available to provide continuous compressor health and performance monitoring.
Throughout the CCS chain, there are critical points where accurate, reliable and traceable measurement of the flow and density of the CO2 is vital. It is essential to know precisely how much gas each emitter injects into the shared pipeline network, and for all parties to have confidence in financial transactions based on these measurements. Companies therefore need to implement dependable measurement solutions, such as highly accurate Coriolis mass flow and density meters, that can tolerate extreme pressures, low temperatures and large swings in density.
I then go on to explain that an important challenge in CCS projects is ensuring that the captured CO2 is transported safely and reliably. Loss of containment undermines the purpose of capturing CO2, so leaks that occur as a result of pipeline corrosion and erosion are a significant concern. The article states:
…Being able to detect and localise pipeline leaks in real time enables operators to address issues faster, so it is essential to implement a monitoring system that provides visibility into pipeline corrosion and erosion. Automation solutions that help operators to maintain a leak-free process include wireless ultrasonic sensors to enable continuous monitoring of pipeline wall thickness, real-time monitoring and alarm solutions to quickly identify leaks and ruptures, and high-performance valves with superior sealing. In addition, software solutions can aggregate disparate pipeline and asset integrity-related data to help identify issues and perform more accurate risk modelling.
To be permitted to enter a shared pipeline network, the composition of the CO2 must fall within certain parameters relating to impurity levels. The presence of impurities can cause damage that leads to dangerous leaks and explosions as the compressed fluid rapidly expands to a gas. Accurate and reliable concentration and composition measurement of the CO2 and its impurities is therefore vital. The article continues:
…Among the advanced automation solutions helping to ensure CO2 integrity are conventional continuous gas analysers which provide real-time analysis of the CO2 composition to a very high degree of accuracy, enabling multiple possible contaminants to be identified, even at very small parts per million. In addition, gas analysers based on chromatography or quantum cascade laser technology offer fast, high-resolution spectroscopy measurements that deliver near-live data and trend information. This visibility into the process allows an emitter to take quick action if impurity levels exceed agreed limits.
Organizations can implement a pre-engineered advanced work package known as a CO2 integrity station, which incorporates a range of automation solutions to ensure that CO2 integrity requirements are met through accurate and reliable measurement, monitoring, analysis and control. In addition to continuous gas analyzers, their base components include Coriolis mass flow and density meters for extremely accurate and reliable measurements; emergency shutdown valves and pressure safety valves to protect equipment; and a remote terminal unit or flow computer that carries out flow rate computations and sends data from the measurement system package equipment to a central control point.
The article concludes by explaining that the success of underground CO2 storage projects depends on the accurate and reliable assessment of storage capacity. It states:
…The highly variable nature of subsurface geological formations and rock characteristics makes such assessments challenging, but the latest exploration and production software, combined with digital twin solutions, provides dynamic simulation modelling of physical environments, which enables accurate mapping and measuring of underground storage complexes.
Visit here to learn more about Emerson’s solutions for optimizing the efficiency of the carbon capture and storage process.
