LES of bicarbonate injection for CO2 storage in seawater based on pH-equilibrated ocean alkalinization

Technologies for carbon dioxide (CO₂) removal and long-term storage should be urgently developed to mitigate climate change. Among various carbon sequestration strategies, CO₂ storage in seawater has emerged as a promising approach with geological timescale storage potential.  The pH-equilibrated ocean alkalinization, an improvement over Accelerated Weathering of Limestone (AWL), facilitates the conversion of CO₂, seawater, and carbonate minerals into bicarbonate-enriched solutions. This process is based on effectively engineering and accelerating the geological weathering process and, supported by extensive experimental data, has been further refined into a scalable solution by Limenet®.The analyzed process is driven by a reaction that produces a pH-balanced seawater-bicarbonate solution, offering dual benefits: CO₂ storage and mitigation of seawater acidification, potentially benefiting marine biota. However, real-world implementation requires effective discharge of bicarbonate-enriched solutions into dynamic marine environments. Existing studies have focused on controlled conditions, leaving a significant knowledge gap regarding free jet discharge in turbulent, variable marine settings. Critical design factors include discharge arrays, temperature, seasonal variability, and the impacts of turbulent mixing and deep-water discharges.This study addresses these gaps using Computational Fluid Dynamics (CFD) to simulate the behavior of bicarbonate discharges in marine environments. Large Eddy Simulations (LES) are employed with OpenFOAMv12 to resolve turbulent scales and model the reaction-convection-diffusion processes. Adaptive Mesh Refinement is used to optimize computational costs, and the seawater equation of state, including temperature and density gradients, follows TEOS-10 standards. The simulations track passive conservative scalars, such as Dissolved Inorganic Carbon (DIC) and Total Alkalinity (TA), using a fictitious equilibrium chemistry approach.The study also explores buoyancy-variable jets influenced by injection temperature and marine conditions such as seasonal temperature gradients and salinity variations. A mesh convergence analysis ensures numerical accuracy, and statistical stationarity is achieved to characterize the naturally unsteady jet dynamics. The findings will elucidate critical hotspots for secondary CO₂ production, assess the influence of marine state characteristics, and establish boundary conditions for larger-scale regional models in a two-way nested framework. By characterizing the spatio-temporal evolution of bicarbonate discharge jets, this work aims to provide a robust framework for future parametric analyses and large-scale industrial implementation. The results will advance understanding of the interplay between chemical, physical, and environmental factors in marine carbon sequestration, contributing to the development of effective, scalable solutions for mitigating atmospheric CO₂ levels.