Geologic Hydrogen: The Next Big Thing in Energy?

The concept of natural hydrogen exploitation has gained traction in recent years, and research efforts in this field have experienced exponential growth. In the absence of sufficient data from deep drilling, researchers and companies are primarily turning towards shallow surface detection methods using soil gas measurements, on the assumption that a deep hydrogen source results in surface emanations. While there is global consensus on the general prospecting method (insertion of perforated probes to a depth of 80 to 100 cm and gas measurement using a portable detector), its many variations often remain poorly documented. The devil is in the details. Our work shows that some of these methods, which are more practical to implement, can induce the mechanical generation of hydrogen during probe insertion, at concentrations sometimes exceeding 1,000 ppm. This analytical artifact can easily be misinterpreted as a significant natural hydrogen discovery.

This finding supports growing calls for the development of best practices in soil gas hydrogen prospecting. But these best practices should not be limited to the research methods used. Should an exploitable reservoir be discovered, the environmental impacts of natural hydrogen exploitation will also need to be examined. Québec has an opportunity to position itself as a leader in the best environmental monitoring practices for this emerging resource in order to responsibly govern its development.

Natural hydrogen (H₂) is generated in the continental crust primarily through Fe²⁺ oxidation during water-rock interaction, and through radiolysis of water by radiogenic elements, the latter co-generating helium (He) and genetically linking the two gases. Canada is well-suited to evaluating these resources, combining the extensive Precambrian Canadian Shield with large sedimentary basins offering potential reservoirs and seals. Here we present the first Canada-wide synthesis of natural H₂ and He systems within a source-migration-reservoir-seal framework adapted from petroleum system analysis. We compiled and harmonized public gas composition data with lithogeochemical datasets, and applied Monte Carlo models of H₂ and He generation by radiolysis and serpentinization, coupled with a Spearman-rank sensitivity analysis. Generation is governed primarily by lithology, age, mineralogy, and lithogeochemistry—F³⁺/FeT ratio for serpentinization and U-Th-K content for radiolysis—whereas accumulation depends on basin architecture, fracture connectivity, and low permeability seals. Million to billion-year-old H₂- and He-rich fracture fluids at Kidd Creek and other Shield mines show that the fractured crystalline basement both generates and retains these gases over geological timescales, complementing trapping potential in the younger basins; helium is both a co-produced resource and a proxy for deep H₂ systems. Modelled rates represent source potential, not recoverable volumes; preservation remains the principal uncertainty; and current anomalies reflect historical exploration rather than true prospectivity. The framework, ranked plays, and datasets provide a transferable foundation for exploring cratonic H₂ and He resources worldwide. Exploration has begun in Canada, with dedicated natural H₂ well drilled in Saskatchewan, and underway in Nova Scotia.

Interest in geologic hydrogen as a primary energy resource has grown recently, as evidenced by exploration activity on every continent. Iron-rich mafic and ultramafic rocks are generally considered the primary source rocks for naturally generated hydrogen. These lithologies are also frequently the host rocks for economically valuable elements such as nickel and chromium. Consequently, the geologic settings that are most prospective for geologic hydrogen are commonly areas that are also of interest for mineral exploration. This provides an opportunity for mineral and hydrogen explorers to leverage the datasets, technologies, and workflows employed in these distinct sectors in their respective exploration efforts. Awareness of the strategies and approaches employed by each of these exploration programs can add benefit to the other. For example, mineral exploration traditionally has utilized explosivity measurements for safety purposes, yet gas compositional analysis would provide valuable information to guide hydrogen exploration. Coproduction of hydrogen and mineral resources (either directly or indirectly via co-location) could significantly lower the OpEx and carbon intensity of mining operations, providing financial and climate benefits. Beyond production of hydrogen from natural accumulations, it is possible that hydrogen could be produced from the subsurface in real-time via stimulated methods. Additionally, above-ground hydrogen generation from iron-rich tailings provides another potential for hydrogen co-production with mineral processing. The possibilities for hydrogen association with mineral resources are largely underexplored and potentially provide an opportunity for industry to lower the cost and environmental impact of mineral extraction.

Compared with synthetic hydrogen, natural hydrogen could represent a low-carbon geo-resource to be developed in the context of the energy transition and the search for new fuels. However, although the existence of natural H₂ emissions has now been established, its economic potential remains to be demonstrated, and several steps can be envisaged: determining whether exploitable natural H₂ reserves and flows exist; understanding the processes responsible for the formation of natural H₂; and assessing whether economically viable exploitation is possible.

This presentation will review recent advances in our understanding of natural hydrogen. It will address the geological processes responsible for its formation, accumulation, and migration in the subsurface, as well as emerging methods for detecting, characterizing, and evaluating potential accumulations.