Hydrogen energy storage in porous media

Abstract

The demand for sustainable and clean energy sources has become increasingly vital in addressing the challenges of climate change and energy security. Hydrogen, with its high energy density and potential for carbon-free energy conversion, has emerged as a promising candidate for future energy systems. Efficient storage and retrieval of hydrogen are crucial for its widespread utilization, for which a promising approach is underground hydrogen storage in geological porous media. This thesis aims to explore and advance the understanding of hydrogen storage in geological porous media, specifically focusing on pore-scale modeling and contact angle analysis.

This research aims to overcome the limitations of current hydrogen storagemethods and develop more efficient energy storage systems. Porous materials like sandstones have special characteristics that make them suitable for storing hydrogen underground. To design and operate underground hydrogen storage on a large scale, it is important to understand how fluids move through these materials. The way hydrogen is stored and released is influenced by complex processes happening at a very small scale (μm). To accurately simulate these processes, we need to study how fluids move in the pores, including factors like capillary pressure (the pressure difference between nonwetting and wetting phases, which is one of the main forces acting at pore scale transport) and relative permeability (how easily fluids flow through the pores where other fluids are also present).

Pore-scale modeling is a useful tool for simulating and understanding how hydrogen behaves in the tiny pore spaces of porous materials. These models help us see how hydrogen moves, spreads out, and interacts with the pore walls at a very small level. Another important aspect is studying the contact angles in the system of hydrogen, water, and porous material. These angles tell us about the way these substances interact at the interfaces between solids, liquids, and gases. By studying these processes and measuring contact angles, we can gain a better understanding of how hydrogen is stored and released, considering factors like pressure, temperature, the type of material, and how easily fluids flow through the pores. This knowledge will help us design better systems for storing hydrogen energy in porous materials on a larger scale.

The primary objectives of this thesis are as follows: To develop pore-scale models for simulating and understanding underground hydrogen storage in geological porousmedia. To investigate the contact angle between hydrogen, brine, and sandstone systems and their influence on storage and release mechanisms. To analyze the contact angle for a mixture of hydrogen-methane in the brine/sandstone system and assess its implications for hydrogen storage. To develop a dynamic pore network model to capture the dynamic behavior of hydrogen in geological porous media. To draw conclusions from the findings and propose future research directions in the field of hydrogen energy storage.