A novel nano-grade organosilicon polymer: Improving airtightness of compressed air energy storage in hard rock formations

Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage (CAES) in hard rock formations. This study introduced a novel approach using a nano-grade organosilicon polymer (NOSP) as a sealant, coupled with an air seepage evaluation model that incorporates Knudsen diffusion. Moreover, the initial coating application methods were outlined, and the advantages of using NOSP compared to other sealing materials, particularly regarding cost and construction techniques, were also examined and discussed. Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10 μm thick NOSP layer. Specifically, under a 0.5 MPa pulse pressure, the permeability decreased to less than 1 nD, and under a 4 MPa pulse pressure, it ranged between 4.5×10⁻⁶–5.5×10⁻⁶ mD, marking a 75%–80% decrease in granite permeability. The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials. The optimal viscosity for application lies between 95 and 105 KU, and the coating thickness should ideally range from 7 to 10 μm, applied to substrates with less than 3% porosity. This study provides new insights into air transport and sealing mechanisms at the pore level, proposing NOSP as a cost-effective and simplified solution for CAES applications.