Pipe-Pile-Based Micro-Scale Compressed Air Energy Storage (PPMS-CAES) for Buildings: Experimental Study and Energy Analysis

摘要

Compressed air energy storage (CAES) technology has been reemerging as one of viable energy storage options to address challenges coming from the intermittency of renewable energy sources, such as solar and wind energy. CAES is believed to have several distinct merits, including low cost, long lifespan, being environmentally benign, and the flexibility of scale and location. The novel concept of pipe-pile-based micro-scale CAES (PPMS-CAES) was proposed by the authors in which the pipe-pile foundations of a building are actively used as air storage vessels as well as load-bearing elements. But to date, the study of the PPMS-CAES has been limited to analytical and numerical research. In this work, the PPMS-CAES idea is examined further by using a model pile that is scaled down from the actual size of a closed-ended pipe pile for a building foundation. During the experiment, the model pile, embedded in a soil chamber, is subjected to a repeated cycle of compressed air charge-discharge for an extended period. Additionally, the test pile with and without a structural load is monitored to investigate its behavior under the different boundary condition. In particular, strain, temperature, and displacement of the test pile are closely monitored during the air pressurization-depressurization cycles. It is confirmed that the repeated operation of compressed air storage does not compromise the mechanical integrity of the pile. The vertical displacement at the pile head is likely to be accumulated during the extended cycle of air storage and discharge, but the rate of displacement gradually decreases during the cycle. And, the presence of a structural load makes a difference in the magnitude of the accumulated vertical displacement. Furthermore, thermodynamic and energy analysis are conducted with the actual measurement data. The analysis shows that the actual operation is close to the isothermal process and demonstrates that the anticipated storage efficiency is very competitive with the tolerable temperature fluctuation during the air storage and discharge. Finally, the energy analysis calculated that the proposed PPMS-CAES concept can be applied to an actual condo, and potentially various other types of residential buildings.