Suguru Uemura

Significance of Micro-Scale Mass Transport Phenomena on Fuel Cells and CO2 Sequestration

We describe micro-scale mass transport plays a key role for R&D of the two realistic countermeasures of global warming, hydrogen fuel-cell energy system and CO2 capture and sequestration (CCS). Understanding of the phenomena based on in-situ measurements leads to the implementation and practical use of these systems. Water inside the fuel cells plays a key role for both cell performance and durability. We have been developing magnetic resonance imaging (MRI) and also soft X ray techniques as in-situ visualization methods for water transport in operational fuel cells. MRI visualization of water content in membrane achieved high spatial resolution, 5 μm, to obtain fundamental insights on water transport process in membrane of 50 μm thickness. Soft X ray has been firstly introduced to measure water transport phenomenon in gas diffusion layer. On the other hand, we clarified CO2 distribution and its behavior by micro-focus X-ray CT and LBM simulation for CCS.Copyright

X-Ray Computed Tomography of CO2 Behavior in Water Saturated Sandstone for Geological Storage

The CO2 Geological storage is considered as an effective technology for reducing the emissions of CO2 into the atmosphere. CO2 storage is a technically feasible and effective method for CO2 mitigation because it is based on enhanced oil recovery technology, and storage sites hold significant potential. Currently, field tests for CO2 geological storage are proceeding in many parts of the world. However, the behavior of injected CO2 is still not completely understood. The CO2 storage potential and risk of leakage from reservoirs must be accurately estimated to realize practicable CO2 storage. For this reason, laboratory-scale experimental analysis of the behavior of CO2 injected in sandstone are an important issues. In this study, CO2 distribution and its behavior in sandstone were observed by micro-focus X-ray computed tomography (CT). The X-ray CT can fluoroscope the CO2 in the porous media and reconstruct a three-dimensional CO2 distribution image. A sample was kept under high pressure conditions in a cylindrical pressure vessel and filled with CO2 saturated water. Pressure in the vessel was kept at 7.5 MPa, which is the same condition as a saline aquifer at 750 m depth. Liquid or supercritical CO2 was injected from the end face of water saturated samples. Temperature conditions were set to 20 or 40°C according to the experimental objectives of the CO2 phase. In the experimental results, CO2 distribution in the silica-packed bed and sandstone was clearly visualized with high spatial resolution compared to its diameter. The possibility of improvement in storage technology discussed.Copyright