Carbon capture and storage (CCS) or utilisation (CCU) of the captured carbon dioxide (CO2) are tools for reducing global carbon emissions, and to combat climate change both are required. In 2021, the global capacity of CCS grew by 48%, showing that this technology is becoming more popular to meet sustainability targets. As ever, with new technologies come new challenges and risks, and this article aims to highlight some potential risks with CCS and CCU technology, and how these risks could be mitigated using modern sensor technology.
CCS technology is in its relative infancy, with less than 50 plants operational today globally. With unknown or new processes comes unknown risk, especially from corrosion. Some recent high profile CCS projects have been delayed owing to a range of factors, including in some cases extreme corrosion caused by contaminants in the piping. This can be costly, with some operators needing to pay to carbon offset their other operations until CCS facilities are operational. The CO2 is almost always stored in a dense phase liquid form, often due to it being easier to transport, and costly pipelines not requiring large diameter piping. Dense phase CO2 is relatively benign in terms of corrosivity, however when liquid CO2 is exposed to water the solubility is extremely high, and as a result a carbonic acid is formed. Carbonic acid can promote general or pitting corrosion, and, in high quantities, could cause a complete loss of containment in days. An event like this could be catastrophic, causing potential loss of life as the highly pressurised CO2 displaces air in the immediate vicinity.
Potential Impact of Corrosion
Testing, undertaken at the DNV Spadeadam facility (see images to the right), shows what might happen if a pipeline containing pressurised CO2 were to rupture. In the imagery, you can see an initial cloud of CO2 quickly turning to gas as the pressure plummets. The heavier than air gas begins to form a visual cloud in the surrounding area up to 300m in height. It took over 3 minutes for the ground level CO2 concentration to dip below 100,000ppm, which is immediately dangerous to life. Any workers in this area would likely have been killed or seriously injured if this were to occur in a production facility.
It is clear that during both design and operation, this risk should be properly considered. Material selection, although playing a significant part, is just one mitigation.
Monitoring the risk and impact of corrosion and erosion using wireless sensors is cost effective and reduces potential leaks into the environment by giving real-time updates on the pipe wall thickness and corrosion rate. Operators can have peace of mind that the facility is operating safely, without the need to pause or shut down the process to install the sensors.
Monitor Risk and Impact
Emerson’s Rosemount Wireless Permasense technology includes a range of non-intrusive sensors for any material and temperature, offering quick and easy deployment of wireless wall-thickness sensors. Sensors are installed anywhere and data gathering begins instantly. Permasense gives wall thickness readings, quantifying the actual amount of metal loss at the pipe wall without needing to stop the process. Data, sent wirelessly, can then be used to remotely monitor the integrity of the piping, and understand any impact of corrosion. Operators can then decide on the correct course of action to mitigate any corrosion.
Online corrosion monitoring is already industry best practice in hydrocarbon facilities, with the availability of data-to-desk monitoring systems that provide previously unachievable quality and frequency of online measurements. 25,000 sensors are operating in over 300 production facilities worldwide, delivering over 35 million wall thickness readings directly to the end users’ desk. Engineers see information on the current condition of the equipment at any point in time with no additional maintenance or costs. The quality and frequency of the measurements enables variations in corrosion to be detected, measured, and acted upon while the plant is operating.
CO2 is a very different product from hydrocarbons, and due to the infancy of CCS technology, risks and mitigations are less well understood. CCS engineering requires curiosity and involves elements of risk, as we as a planet aim to reach net zero by 2050. Thankfully, technology solutions allow us to take risks and see the effects in real time. In order to reach the targets agreed by the International Energy Agency, installation of corrosion monitoring in carbon capture facilities will become commonplace in the next decade, as the demand for carbon capture continues to grow, along with the associated risks.