As hydrogen emerges as a critical energy storage solution, underground storage facilities are in the spotlight, offering vast potential for large-scale, green hydrogen storage. However, storing hydrogen underground isn’t as simple as it sounds. Hydrogen storage sites experience regular cycles of injection and production, causing fluctuating pressures and stress on the surrounding rock. New research led by Reza Abdollahi from the University of Adelaide has developed a sophisticated hydro-mechanical model to predict these changes, paving the way for safer, more reliable hydrogen storage solutions.
Addressing a Unique Challenge: Stress Accumulation
While underground storage is well established for natural gas, hydrogen introduces unique challenges due to its lightweight, highly diffusive nature. Unlike natural gas, hydrogen storage involves rapid and repeated injection and withdrawal cycles to meet energy demands. These cycles cause stress accumulation and pressure variations within the storage reservoir, potentially destabilising the site and impacting storage safety. In this study, Abdollahi’s team focused on understanding these cumulative stresses, an aspect crucial for designing safe and durable hydrogen storage systems.
The Innovation: A Model Tailored for Cyclic Loading
This model, grounded in the principles of poroelasticity (how fluids interact with porous rock under stress), combines two elements: mass diffusion and displacement analysis. By incorporating cyclic patterns, the model simulates repeated hydrogen injection and production, something existing models for natural gas storage are less equipped to handle. The research validates the model’s accuracy by comparing it against numerical simulations, achieving results within a 1% margin of error—a promising indicator of reliability.
Practical Insights: Reducing Risks and Improving Safety
One key finding is that stress does not reset after each cycle; instead, it accumulates over time, posing risks for structural integrity. The model suggests that adding relaxation periods between cycles can allow the stress to dissipate, maintaining reservoir stability. This discovery has implications for industry practices, as periodic relaxation phases could become standard to prevent potential failures or even seismic events.
A Step Toward Robust Hydrogen Storage Infrastructure
This new modelling tool gives engineers a cost-effective, fast screening method to evaluate potential sites and plan operational cycles effectively. As underground hydrogen storage is scaled up to meet growing energy needs, insights from this model could be instrumental in ensuring safety and sustainability. With such advancements, underground hydrogen storage is poised to play a secure and reliable role in our global transition to green energy.
Source
Reza Abdollahi, Abbas Movassagh, Dane Kasperczyk & Manouchehr
Haghighi (2024) Coupled hydro-mechanical model for underground hydrogen storage
undergoing cyclic injection and production, Energy Sources, Part A: Recovery, Utilization, and
Environmental Effects, 46:1, 14839-14855, 2024-10-15
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