Heriot-Watt to examine thermodynamics of CCUS fluids

Jointly funded by TotalEnergies and Equinor, the two-year project aims to improve thermodynamic models to predict the phase behaviour of CO2 rich mixtures, specifically focusing on volatile organic compounds (VOCs) as the impurities. 

The project outcomes will be pivotal in establishing optimum operational conditions throughout the CCUS chain, plus environmental compliance and proper CO2 storage.

In CCUS systems, VOCs are often found in the captured CO2 stream, primarily originating from the source of the CO2. VOCs include benzene, toluene, xylene (BTX), aldehydes (formaldehyde, acetaldehyde), and various hydrocarbons depending on the fuel source and capture conditions.  

In a statement, Dr Pezhman Ahmadi, project lead from the specialist Hydrate, Flow Assurance and Phase Equilibria (HFAPE) research group, said: "For safety and technical reasons, understanding the thermodynamic behaviour of a fluid is key to its successful processing, transportation, and storage.

“In CCUS projects, where the working fluid is usually a CO2 rich mixture, the presence of impurities significantly influences the behaviour of the fluid in comparison to a pure CO2 stream. While thermodynamic models for pure CO2 are reliable thanks to abundant experimental data, impure CO2 streams, which are common in industry, pose challenges due to limited data and deficiencies in existing models. This project focuses on VOCs as a critical category of impurities so we can better understand the influence of this type of impurities and address this data gap."

Industry collaboration

Since the institution’s first CCUS related joint industry project (JIP) in 2011, led by Professor Antonin Chapoy, a specialist research group has developed advanced laboratories and expertise in experimental and modelling studies of the thermophysical properties of CCUS fluids.

The group collaborates with over 10 major CCUS operators globally through consultancy and research projects.

Professor Chapoy, project co-lead on the latest effort, said: "Our modelling studies, underpinned by experimental capabilities and expertise, provide precise thermodynamic models that improve the safety, technical and economic aspects of CCUS operations. These models help reduce operational risks, such as hydrate or dry ice formation, and minimise costs while enhancing efficiency in the transportation and storage of CO2-rich fluids. Over the years, our work has supported major CCUS operators in achieving safer and more cost-effective operations."