Investigation of a small-scale compressed air energy storage pile as a foundation system

Compressed air energy storage (CAES), in which surplus energy is utilized for compressing ambient air that can be released later to provide necessary energy, is being actively pursued in a last decade. This technology has a potential to strengthen the efficiency of renewable energy generation, such as solar and wind power. In addition to the large-scale energy storages, CAES can be operated at a small-scale to support facilities such as residential buildings. In this case, closed-ended steel piles can serve to provide the space where pressurized air is stored during off-peak periods, which leads to an idea of small-scale CAES pile. To continue pursuing the idea of using pile foundation system as an energy storage vessel, we need to examine long-term stability of CAES pile. In this pilot study, we investigate a finite element model of an axisymmetric CAES pile that is subject to the internal uniform pressurization while supporting a constant structural load. Long-term stability of the CAES pile is assessed from the first 10 pressurization-depressurization cycles at the various initial dead load conditions. Elasto-perfectly-plastic constitutive law is employed at the pile-soil interface for simplicity. We are able to observe that vertical displacement of the CAES pile accumulates with negligible radial deformation as the number of pressure cycle increases.