Modeling and Simulation for Sustainable Energy and Resources: Water Filtration systems and Underground Hydrogen Storage

Sustainable development has emerged as the defining human challenge of this century because of the sharp conflict between sustainability and current development practices. Among those conflicts, many populations are faced with severe water shortages, as well as greenhouse effects due to combustion of fossil fuels. For the purpose of realizing the transition to sustainable development and societies, new technologies and policies must be developed and implemented. While new approaches and technologies span a large variety of methods and application areas, we will focus on the analysis and study of two specific technologies: reverse osmosis (RO) membrane systems for water purification and underground hydrogen storage. In this thesis, we use a combination of mathematical modeling and numerical simulations to investigate, understand and predict the system response.
In the first part of the thesis, we focus on RO membranes, an existing technology whose impact on access to potable water is expected to grow significantly in the near future. Fundamental knowledge of the physical processes governing flow and transport in RO systems is critical to guide their design and optimization for maximum performance under different operating conditions. In particular, we study the impact of turbulent flow on RO systems performance through the extension of the in-house solver SUMembraneFOAM to turbulent flows, and derive a new Reynolds-Sherwood correlation, routinely used to design system-scale modules, in turbulent conditions. A classical approach to quantify membrane performance, and its propensity to foul, is to estimate concentration polarization (CP) in proximity of the membrane surface. Currently, classical thin film theory is used to approximate CP under specific flow conditions. We derive an analytical and exact expression to calculate CP in RO systems and demonstrate its accuracy. In the second part of the thesis, we focus on a preliminary study of subsurface H2 storage. It is currently suggested that H2 subsurface storage does not present additional challenges to those typically associated with CO2 storage. Here, we critically assess this hypothesis by quantitatively investigating the potential (dis)similarities between the behavior of H2 underground and that of CO2. Our preliminary investigation warns that unique and additional modeling challenges may be expected in the context of H2 underground storage, especially in reference to the validity of multiphase Darcy’s law. This knowledge is critical to assess the feasibility to store hydrogen, guide the design, optimize site selection, and achieve the storage capacities that are necessary for the transition to a net-zero emission energy system.