Systematic review of Brazil’s evaporite basins for large-scale hydrogen cavern storage

Abstract Underground hydrogen storage (UHS) in solution-mined salt caverns is widely viewed as one of the most scalable ways to buffer variability in low-carbon power systems and to underpin large hydrogen hubs. Brazil contains multiple onshore and offshore evaporite provinces, but their relative suitability for cavern-based UHS remains unevenly consolidated across the literature. Here we present a screening-level assessment of eleven Brazilian sedimentary basins that contain evaporites, integrating published stratigraphic and structural constraints with engineering-relevant evidence within a transparent classification matrix. We rank basins using six criteria: (i) depth to the salt roof within an operational window relevant to cavern construction, (ii) effective (usable) halite thickness, (iii) salt purity and lateral/vertical homogeneity, (iv) structural setting and associated risks (e.g., faulting, diapirism, and, where applicable, magmatic intrusions), (v) proximity to energy infrastructure and logistics, and (vi) data quality and subsurface characterization maturity. The screening identifies the strongest overall suitability where thick, comparatively homogeneous evaporites occur within favorable depth ranges and are constrained by robust subsurface datasets, most consistently in Sergipe–Alagoas and several offshore margin basins. By contrast, basins with limited usable thickness, sparse data coverage, and/or higher structural complexity yield lower screening scores and require targeted appraisal before advancing to site selection. Order-of-magnitude capacity estimates based on mapped usable salt areas indicate that large cavern inventories could be developed in basins with extensive evaporite footprints, subject to site-specific constraints on geomechanical integrity, wellbore design, and the continuity and performance of the sealing system. Overall, the results provide a structured basis for prioritizing data acquisition and de-risking next-step feasibility studies aimed at integrating cavern clusters into Brazil’s emerging hydrogen value chains.