Curbing Emissions: Flow Assurance Models Unlock the Power of CCUS

May 09, 2023   Written by Alessandro Speranza and Michelle Wicmandy

Rising greenhouse gas emissions are causing concern. According to Our World in Data, around 34 billion tonnes of emissions from fossil fuels are emitted each year, compared to 22 billion tonnes in 1990. While the priority should be to curb emissions, especially Scope 1 and Scope 2, all relevant hypothetical scenarios show that current reduction efforts aren’t enough to meet today’s decarbonization targets.   

Curbing Emissions

Nonetheless, did you know that alternative and complementary solutions can play a key role on your path to net zero? According to the International Energy Agency Sustainable Development Scenario, nearly 15% of cumulative emissions reductions are attributed to carbon capture, utilization and storage (CCUS) assuming net global carbon emissions from the energy sector fall to zero on a net basis by 2070. Furthermore, research shows that power and industrial plants equipped with just CCS technology can capture about 90% of the CO2 emitted from burning fossil fuels. Even with these advances, we need to capture more CO2 for CCS (or CCUS) to contribute to the shift towards net zero. 

Recently, the Intergovernmental Panel on Climate Change special report identified four possible scenarios to achieve net zero, three of which require CCS projects to reduce emissions. In practice, several studies argue that there is no realistic path to net zero without CCS. This is particularly true for hard-to-abate industries, such as cement, iron and steel production, or chemical processes. 

In this context, it is therefore crucial to establish the most favourable operating conditions for CCS projects to succeed. The peculiar thermal properties of CO2 make it necessary to understand how the CCS gas behaves under operating conditions and how common impurities affect it. Being able to predict these aspects accurately is essential to design the facilities and identify the operating envelope. 

Applying Flow Assurance Models

Our recent study, Net zero Flow Assurance – Validation of various equations of state for the prediction of VLE and density of CO2-rich mixtures for CCUS application, examines a systematic comparison of a large dataset of reliable experimental data of the phase behaviour (e.g. saturation data) and physical properties (e.g. the density of the CO2 rich phase), with predictions from popular thermodynamic models for CCS applications (see Figure 1). The results show that our Corresponding States Model Advanced (CSMA) and GERG-2008 in Multiflash® provide a good basis for mixtures of which we have availability of high accuracy equations of state and BIPs (binary interaction parameters). For more general applications, CPA (Cubic Plus Association) and cubic equations of state (e.g. Peng-Robinson Advanced) may also provide a good basis, especially for vapour-liquid equilibrium (VLE) predictions. However, physical and transport properties may be less well represented, and in general, predictions depend heavily on tuning the BIPs for each pair. 

Phase diagram of a simple CCS gas mixture exhibiting formation of hydrates and solid CO2 at low temperature

Figure 1: Phase diagram of a simple CCS gas mixture exhibiting formation of hydrates and solid CO2 at low temperature.

Optimizing CCUS Applications

As industries evolve, carbon dioxide management is becoming a major issue to reduce emissions. Designing and managing CCUS projects accurately is important in terms of controlling costs and accurately predicting thermodynamic properties in the presence of impurities. For more information on how Multiflash can help you discover the accuracy of your thermodynamic models for CCUS applications, please contact Alessandro Speranza.