In the quest for safer and more efficient energy storage solutions, a team of researchers from China University of Geosciences (Wuhan) and Chang’an University has made significant strides in understanding how granite behaves under ultra-low temperatures, a critical factor for underground liquefied natural gas (LNG) storage facilities. Their findings, published in the journal *Yantu gongcheng xuebao* (translated as *Rock and Soil Mechanics*), offer valuable insights that could reshape the future of energy infrastructure.
Liquefied natural gas, stored at temperatures as low as -162℃, poses unique challenges to the surrounding rock formations. Granite, a widely distributed and high-strength rock, is often considered an ideal medium for such storage. However, the extreme temperatures can alter the granite’s properties, potentially compromising storage safety. This is where the research led by Dr. Li Chunchun and her team comes into play.
The team conducted a series of experiments, including uniaxial compression, thermal expansion, and microscopic tests, to investigate the mechanical properties of both dry and saturated granite at temperatures ranging from -90℃ to -165℃. Their results were enlightening. “We found that as the temperature decreases, the compressive strength and elastic modulus of saturated granite increase significantly,” Dr. Li explained. “For dry granite, while the compressive strength remains relatively stable, the elastic modulus increases notably.”
The team attributed these changes to the freezing of pore water in saturated granite, which tightens the rock’s voids and cracks, making the internal structure denser. In dry granite, the shrinkage of minerals due to temperature decrease enhances the bonding of internal particles. These findings have profound implications for the energy sector, particularly for companies investing in underground LNG storage facilities.
One of the most compelling aspects of this research is the development of an empirical formula that correlates the rock’s linear expansion coefficient with temperature. This formula has been integrated into a thermal-mechanical coupling model in COMSOL, a software used for simulating physical and chemical phenomena. The model allows for long-term stability analysis of low-temperature LNG storage facilities, providing a crucial tool for predicting and mitigating potential risks.
Dr. Xiong Feng, a co-author from Chang’an University, highlighted the practical applications of their work. “Our research provides a scientific basis for the design and safety assessment of underground LNG storage facilities,” he said. “By understanding how granite behaves under ultra-low temperatures, we can better predict the long-term stability of these facilities and ensure their safe operation.”
The study also sheds light on the phenomenon of frost heave, a process where the surrounding rock of underground storage facilities undergoes compression deformation due to temperature decreases. This can lead to surface uplift, posing a risk to the stability of the storage facilities. By understanding and predicting these effects, engineers can design more robust and safer storage solutions.
The implications of this research extend beyond immediate safety concerns. As the world increasingly turns to natural gas as a cleaner energy alternative, the demand for efficient and safe storage solutions will only grow. This study provides a critical foundation for future developments in underground space engineering, paving the way for more reliable and secure energy infrastructure.
In the words of Dr. Li, “Our findings are not just about understanding the behavior of granite under extreme temperatures. They are about ensuring the safety and efficiency of our energy infrastructure, which is crucial for a sustainable energy future.” With their groundbreaking research, Dr. Li and her team have taken a significant step towards that future, offering valuable insights that will shape the energy sector for years to come.