Harnessing sediment voids of low-grade salt mines for compressed air energy storage: Experimental and theoretical insights

• Compressed air effectively displaces brine from sediment voids in low-grade salt caverns, enabling CAES utilization. • A 0.5 MPa injection pressure in experiments corresponds to a 10.3 MPa operational lower limit in practice, validated by field data. • Sediment voidage in the Huai’an salt mine is approximately 46%, confirmed via air-brine interface theory. • The 'two injections and one discharge' mode outperforms 'one injection and one discharge' in both brine discharge volume and rate.