The USGS Geologic Hydrogen Project conducts research on naturally occurring hydrogen across the nation and the world. The project provides critical scientific insight and data that support the discovery, assessment, and responsible management of geologic hydrogen resources. Research efforts are focused on understanding the natural processes that could lead to recoverable geologic hydrogen resources, as well as developing exploration tools and strategies that could assist in resource discovery and extraction. The goal is to improve our understanding of this previously unrecognized energy resource to help meet the nation’s future energy needs.
Hydrogen gas (H2) is a critical feedstock for a variety of industrial processes, most notably petroleum upgrading, steel manufacturing, and fertilizer production (Energy Information Agency). The use of H2 as an energy source today is generally restricted to rocket fuel and specialized applications (e.g., electricity generation on spacecraft); however, it is projected to play an increasingly important role in future energy supplies. Hydrogen can be produced by a variety of processes; however, most commercially available H2 today is produced by the high-temperature reaction of water and coal or methane, which releases approximately 10–12 kg of carbon dioxide (CO2) to the atmosphere for every 1 kg of H2 produced (International Energy Agency). Global production of H2 in 2024 was approximately 100 Mt (million metric tonnes) of which less than 1% was low carbon (International Energy Agency). Energy policy analysts predict that the demand for hydrogen will more than double (~200 Mt) by 2030 to meet 2050 decarbonization goals and that much of this will need to come from low-carbon sources (International Energy Agency). To achieve climate objectives, these projections involve methane derived H2 coupled with carbon sequestration (blue H2), and H2 generated by electrolysis of water using renewable sources of electricity (green H2). Reaching these goals will require an unprecedented investment in new technology and infrastructure (International Energy Agency).
Although naturally occurring hydrogen has been encountered in a wide variety of subsurface environments, millions of oil and gas wells have failed to detect more than trace concentrations of hydrogen, with a few notable exceptions. This led many geoscientists to conclude that economic accumulations of hydrogen in the subsurface are non-existent, likely due to the high diffusivity and reactivity of hydrogen, which may limit its geologic residence time (Gaucher, 2020). Recent discoveries in Mali, Albania, and elsewhere have led geoscientist to question the notion that accumulations of H2 could not be present in the subsurface. It is clear now that geoscientists were premature in concluding that economic accumulations of natural hydrogen could not exist in the subsurface. The right tools have not been deployed in the right places to assess the prospects of natural hydrogen resources. Exploration for geologic hydrogen is currently underway in Albania, Australia, Canada, Colombia, France, Finland, Korea, Spain and the United States, and likely in other countries too (International Energy Agency). It is estimated that there were more than 40 companies exploring for geologic hydrogen resources at the end of 2023, a fourfold increase since 2020.
A recent study by the USGS estimates that there could be millions of Mt of natural hydrogen in accumulations in the Earth’s crust (Ellis and Gelman, 2024). However, there is a great deal of uncertainty associated with this prediction and the model does not evaluate the potential size or distribution of hydrogen accumulations. Most of this hydrogen is likely to be in accumulations that are too deep, too far offshore, or too small to ever be economically recovered. That said, even a small fraction of the estimated amount of subsurface hydrogen could potentially meet all global projected demand for hundreds of years. Consequently, the key to understanding geologic hydrogen resource potential is to examine the geologic factors that affect the potential to form accumulations.
Understanding Geologic Hydrogen Systems
To develop effective strategies for exploration and assessment of geologic hydrogen resources, a comprehensive framework is required that elucidates the essential components that could lead to economic hydrogen accumulations (Jackson et al., 2024). The first objective of this project is to develop and refine a hydrogen system model that is based on the highly successful “petroleum systems” concept (Magoon and Dow, 1994) and is specifically tailored to understanding the generation of economic accumulations of hydrogen resources in the Earth’s subsurface. Research into the hydrogen system is focused on improving our understanding of the mechanisms of generation, migration, trapping, and preservation of hydrogen in the subsurface. Given the highly complex and interdisciplinary nature of this research, much of it is being done in collaboration with partners in academia and industry through a USGS-Colorado School of Mines research consortium.
Mapping Prospectivity for Geologic Hydrogen
Given our nascent understanding of the potential for geologic hydrogen resources and the very limited amount of data that are available from known accumulations, it is currently not possible to quantitatively assess the resource potential. However, the hydrogen system model can be used to determine regions that are prospective for geologic hydrogen resources. The second objective of the project is to develop and refine a prospectivity mapping methodology, based on the hydrogen system model, that determines the most prospective regions for discovery of geologic hydrogen resources and can be applied to specific regions of interest. The USGS has now developed a rigorous methodology for mapping the relative prospectivity where conditions are favorable for the accumulation of naturally occurring hydrogen (Gelman and others, 2025). The methodology has been applied to the lower 48 states of the US and identifies many regions of the country as prospective for geologic hydrogen, indicating that these regions have the necessary geological conditions—hydrogen sources, reservoir rocks, and seals to trap the gas—for hydrogen accumulation. The geologic hydrogen prospectivity map for the contiguous 48 US states can be viewed here, the data for the map is available here.
Application of Surface Geochemistry to Geologic Hydrogen Exploration
It is worth noting that currently there is a general lack of tools and strategies for exploration of geologic hydrogen resources. A wide variety of techniques that are employed in petroleum, mineral, and geothermal energy resource exploration may be applicable in hydrogen exploration; however, they likely need to be adapted to be optimal for hydrogen exploration. The third objective of this project is to identify and develop surface technologies that may be useful in hydrogen gas exploration. Surface seeps of petroleum played an important role in the early days of oil and gas exploration, and detection of hydrogen and associated gases in near subsurface settings may help identify viable hydrogen systems in the subsurface. Additionally, there is a need for more comprehensive and accurate observations of natural hydrogen flux in near subsurface settings to better constrain the global hydrogen biochemical cycle. As use of hydrogen expands around the globe in the future, there will be an increased need to monitor unintentional anthropogenic contributions of hydrogen to the atmosphere. Proper assessment of stray hydrogen impacts on atmospheric chemistry requires an accurate understanding of natural hydrogen fluxes.
Frequently Asked Questions (FAQ)
What is geologic hydrogen?
Geologic hydrogen, also known as natural hydrogen, is hydrogen gas that is naturally found below the surface of the Earth. Unlike hydrogen produced through industrial processes, geologic hydrogen is sourced by and stored in rocks in the ground, similar to traditional petroleum resources.
Why is geologic hydrogen important?
Hydrogen is a clean fuel, meaning when it burns, it only produces heat and water as a byproduct. This makes it attractive as an alternative to fossil fuels, which release carbon dioxide. Geologic hydrogen has the potential to be a sustainable and environmentally friendly energy source within the United States and around the world.
How is geologic hydrogen formed?
Geologic hydrogen is formed through natural processes deep within the Earth. One common way it forms is through a reaction between water and certain iron-rich rocks, a process known as serpentinization. Another common way it forms is through the process of radiolysis, where natural radiation deep in the Earth breaks down water molecules to produce hydrogen.
Why haven’t we found geologic hydrogen before?
A simple explanation is that we haven’t been looking in the right places with the right tools. Historically, subsurface energy drilling was not targeting hydrogen gas and companies often didn’t account for it during exploration. More importantly, geologic settings where hydrogen generation is likely to occur are not the same places where petroleum is found. There are potentially large amounts of geologic hydrogen waiting to be discovered, which could provide a long-term, clean energy source.
Learn more by watching this video: https://www.aapg.org/career/training/in-person/distinguished-lecturer/abstract/articleid/67621
