Preparation and pipeline transport of CO2 as a hydrate slurry – Modelling and techno-economic analysis

CO₂ transportation as a hydrate slurry is modelled in Aspen Plus, including the slurry preparation and the pipeline transport. Due to the lack of built-in models for the hydrate formation, mass and energy balances were developed and implemented using a User-block function. NRTL-RK global property method was used, given the accuracy in predicting the CO₂ solubility in water under incipient hydrate formation conditions and the dissolution heat of CO₂ in water. The conventional process of transporting CO₂ in a supercritical state was also modelled to benchmark the hydrate-based technology. The hydrate-based process is safer than the conventional process as it requires lower operating pressures, but the estimated costs are higher due to the need for refrigeration and larger pipeline diameters for transportation. The addition of thermodynamic promoters, that moderate the hydrate formation conditions, the integration of cold streams with other processes, and valuing the water transported with CO₂, will enhance the economic attractiveness of the hydrate-based process.