A Novel Polymerized Sulfur Concrete for Underground Hydrogen Storage in Lined Rock Caverns

Hydrogen is increasingly recognized as a viable solution to meet the growing global energy demand, making large-scale hydrogen storage essential for successfully realizing a full-scale hydrogen economy. Geological formations, such as depleted oil and gas reservoirs, salt caverns, and aquifers, have been identified as potential storage options. Additionally, unconventional methods like manufactured lined rock caverns and abandoned coal mines are gaining interest. This study introduces polymerized sulfur concrete (PSC) as a promising alternative to replace the current construction systems, which rely on Portland cement concrete and lining materials like stainless steel or polypropylene plastic liners. The paper presents the formulation of PSC, optimization of its compositional design, and evaluation of its physico-mechanical-chemical properties. The results demonstrate that PSC offers excellent mechanical strength, chemical resistance, and low permeability, making it highly suitable for underground hydrogen storage in lined rock caverns. The results showed that the manufactured PSC exhibits excellent physicochemical properties in terms of compressive strength (35–58 MPa), density (2.277–2.488 g/cm 3 ), setting time (30–60 min), curing time (24 h), air content (4–8%), moisture absorption potential (0.17–0.3%), maximum volumetric shrinkage (1.69–2.0%), and maximum service temperature (85–90 °C). Moreover, the PSC is nonconductive and classified with zero flame spread classification and fuel contribution. In addition, the SPC was found to be durable in harsh environmental conditions involving pressure, humidity, and pH variations. It is also capable of resisting corrosive environments. In addition, the statistical modeling indicates that an overall mixture proportion of 32.5 wt.% polymerized sulfur, 32.5 wt.% dune sands, 17.5 wt. % LFS, and 17.5 wt.% GGBFS appear optimal for density values ranging from 2.43 to 2.44 g/cm 3 and compressive strength ranging from 52.0 to 53.2 MPa, indicating that the PSC can sustain formation pressure up to about 5.3 km below the ground surface. Therefore, by addressing the critical limitations of traditional materials, PSC proves to be a durable, environmentally sustainable solution for lined rock caverns, reducing the risk of hydrogen leakage and ensuring the integrity of storage systems.