Hydrogen is an attractive, clean, sustainable energy source primarily produced via industry. At present, most reviews on hydrogen mainly focus on the preparation and storage of hydrogen, while the development and utilization of natural hydrogen will greatly reduce its cost. Natural hydrogen has been discovered in many geological environments. Therefore, based on extensive literature research, in this study, the distribution and sources of natural hydrogen were systematically sorted, and the identification method and occurrence state of natural hydrogen were examined and summarized. The results of this research show that hydrogen has been discovered in oceanic spreading centers, transform faults, passive margins, convergent margins, and intraplate settings. The primary sources of the hydrogen include alterations in Fe(II)-containing rocks, the radiolysis of water, degassed magma, and the reaction of water- and silica-containing rocks during the mechanical fracturing. Hydrogen can appear in free gas, it can be adsorbed and trapped in inclusions. Currently, natural hydrogen exploration is in its infancy. This systematic review helps to understand the origin, distribution, and occurrence pattern of natural hydrogen. In addition, it facilitates the exploration and development of natural hydrogen deposits, thus enabling the production of low-cost hydrogen.

Earth has a prolonged history characterized by substantial cycling of matter and energy between multiple spheres. The production of organic carbon can be traced back to as early as ∼4.0 Ga, but the frequency and scale of organic-rich shales have varied markedly over geological time. In this paper, we discuss the organic carbon cycle and the development of black shale from the perspective of Earth System Science. We propose that black shale depositions are the results of interactions among lithospheric evolution, orbital forcing, weathering, photosynthesis and degradation. Black shales can record Earth's oxygenation process, provide petroleum and metallic mineral resources and reveal information about the driver, direction and magnitude of climate change. Future research on black shales should be expanded to encompass a more extensive and more multidimensional perspective.

Hydrocarbon accumulation and resources evaluation: Recent advances and current challenges

The paper adopts an interdisciplinary approach to comprehensively review the current knowledge in the field of porous geological materials for hydrogen adsorption. It focuses on detailed analyses of the adsorption characteristics of hydrogen in clay minerals, shale, and coal, considering the effect of factors such as pore structure and competitive adsorption with multiple gases. The fundamental principles underlying physically controlled hydrogen storage mechanisms in these porous matrices are explored. The findings show that the adsorption of hydrogen in clay minerals, shale, and coal is predominantly governed by physical adsorption that follows the Langmuir adsorption equation. The adsorption capacity decreases with increasing temperature and increases with increasing pressure. The presence of carbon dioxide and methane affects the adsorption of hydrogen. Pore characteristics—including specific surface area, micropore volume, and pore size—in clay minerals, shale, and coal are crucial factors that influence the adsorption capacity of hydrogen. Micropores play a significant role, allowing hydrogen molecules to interact with multiple pore walls, leading to increased adsorption enthalpy. This comprehensive review provides insights into the hydrogen storage potential of porous geological materials, laying the groundwork for further research and the development of efficient and sustainable hydrogen storage solutions.

The origins of natural hydrogen in natural gas systems of sedimentary basins and the capacity of these systems to store hydrogen remain inadequately understood, posing crucial questions for the large-scale exploration of natural hydrogen. This study reports on the natural gas composition, stable carbon and hydrogen isotopic values, and helium isotopic values of gas samples collected from the Qingshen gas deposit within volcanic rocks of the Songliao Basin. Natural hydrogen primarily originates from water radiolysis, water-rock interactions (WRI), and mantle. The Qingshen gas deposit contains 95.23 × 10 ⁹ cubic meters of abiotic CH ₄ , of which 15.24 × 10 ⁹ cubic meters was generated through hydrogen conversion via Fischer-Tropsch synthesis, with the maximum original hydrogen reserves calculated to be approximately 61.9 × 10 ⁹ cubic meters. We estimated that the study area has generated a maximum total of 572 × 10 ⁹ cubic meters of radiolytic hydrogen, 248 × 10 ⁹ cubic meters of WRI hydrogen, and 127 × 10 ⁹ cubic meters of mantle-derived hydrogen.