Skip to main content
TU-Clausthal Sino-German-Energy

Underground energy storage

In China, research into underground salt cavern energy storage is still in the early stages. The main difference in the construction of underground storage facilities between Germany and China is that in Germany there are sufficiently thick salt domes (from several hundred to several thousand meters) with a high NaCl content (up to 95%) and a low proportion of insoluble impurities, while in China there are only horizontal salt deposits with a thickness of less than 300m and a high proportion of impurities (15%-25%), as well as intermediate agents. Compared to Germany, the following research is being carried out in China in particular:

  • Investigation into the mechanical properties of Chinese rock salt with a high proportion of impurities and intermediate layer (often claystone)
  • Development of a suitable material model for the mechanical properties of Chinese salt deposits with a high level of impurities
  • Optimization of the dimensioning concept, taking into account safety and economic efficiency, including structural damage, but also damage regression and healing in dilatant rock salt. This is because the geological difference between the German and Chinese salt deposits has an effect on the dimensioning and cavern geometry.
  • Investigation to optimize the operating parameters and long-term load-bearing behaviour of natural gas storage caverns, particularly in horizontal, thin salt deposits

 

Within the cooperation group, Chinese and German scientists are currently working on the following research topics:

  • Experimental studies on the healing behavior of rock salt. Answering the questions: Under what conditions and how are existing structural damages in rock salt regressed or even completely healed?
  • Experimental studies on the permeability behavior of rock salt with different proportions of impurities and on the coupling of damage, porosity and permeability in dilatant rock salt. Answering the questions: What is the relationship between permeability, impurity, volume dilatancy and compaction, structural damage and healing as well as the stress state?
  • Experimental and numerical investigations on the thermal-hydraulic-mechanical coupled behavior of rock salt (THM behavior). The results can also be used in connection with radioactive disposal in salt formations.
  • Benchmark research of the German and Chinese material models of rock salt: Comparative analysis of the German and Chinese material models of rock salt
  • Investigation of the impact of accidents on caverns and development of measures to reduce storage damage
  • Similar to pumped storage plants, compressed air energy storage (CAES) is a possibility for the extensive storage of electricity. Ambient air is compressed and stored in underground cavern storage facilities for the purpose of storage. When required, during peak load periods, the system passes the compressed air through an expansion turbine and generates electricity. Power generation from compressed air storage power plants is also seen as an important development direction in the future, as it helps to evenly utilize the power grids. The basic theories for natural gas salt cavern storage can be applied to compressed air cavern storage due to its comparability with natural gas salt cavern storage. However, due to the short injection and production period of a compressed air cavern storage facility and the resulting internal stress changes, further research is required into the structural damage and healing behavior of the rock salt, which has not yet been investigated.