Geologic Hydrogen Prospectivity Map Explorer
The Geologic Hydrogen Prospectivity Map Explorer hosts various geologic and geophysical data layers in support of the U.S. Geological Survey’s initiative to map the potential of geologic hydrogen within the conterminous U.S. This first-ever Hydrogen Map Explorer contains 19 input maps and 7 integrated maps that highlight prospective areas for naturally occurring hydrogen across the country.
Geologic Hydrogen Overview
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 natural gas resources.
Why is it Important?
Hydrogen is a clean fuel, meaning when it burns, it only produces water as a byproduct. This makes it an attractive 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 it 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 vast reserves of geologic hydrogen waiting to be discovered, which could provide a long-term, clean energy source.
Maps of Geologic Hydrogen Potential
Here we present the inputs and resulting maps for geologic hydrogen prospectivity within the conterminous United States. These maps were created based on our interpretation of the geologic hydrogen system model and our comprehensive knowledge of the geology of the United States. For more information on our data and methods, please refer to the publication (https://doi.org/10.3133/pp1900) and the associated data release here: https://doi.org/10.5066/P13WCG5U.
Available Map Layers
Geologic Audit
Known Hydrogen Occurrences
This layer shows known hydrogen occurrences within the conterminous United States with values greater than 1 mol % from Zgonnik (2020; https://doi.org/10.1016/j.earscirev.2020.103140), the U.S. Geological Survey Energy Geochemistry Database (2019; https://certmapper.cr.usgs.gov/data/apps/geochem-db/), and Brennan and others (2021; https://doi.org/10.5066/P9TR93E3).
Known Helium Occurrences
This layer shows known helium occurrences within the conterminous United States with values greater than 0.3 mol % from Brennan (2021; https://doi.org/10.5066/P92QL79J). Helium is often sourced from and found in the same places as geologic hydrogen.
Isolated Geothermal Systems
This layer shows areas with known geothermal systems from the layer "USGS_Isolated_Geothermal_Systems" within NREL's geothermal prospector (https://maps.nrel.gov/?da=geothermal-prospector). Geothermal and hydrothermal systems are known to contain hydrogen gas.
Carolina Bays
This layer illustrates features called Carolina bays from Lundine and Trambanis (2021; https://doi.org/10.3390/rs13183770). These ovoid features are hypothesized to be the surficial expressions of subsurface, migrated hydrogen.
Source: Serpentinization
A natural chemical process between iron-rich rocks and water that alters the rock and releases hydrogen gas.
SP1: East Coast Magnetic Anomaly
This layer illustrates the area defined by the east coast magnetic anomaly (EMCA) and was created by digitizing the ECMA from Biairi and others (2017; https://doi.org/10.1002/2017TC004596). The ECMA is expressed as an offshore, high-amplitude, positive magnetic anomaly that may represent the presence of subsurface ultramafic rocks, which can be a hydrogen source. Migration pathways were applied to this layer and show westward migration from this offshore feature to the east coast of the US.
SP2: Surface Ultramafics
This layer illustrates areas where ultramafic and other iron-bearing rocks are present at the surface, and are inferred to extend into the subsurface as a potential hydrogen source. The layer represents a combination of data from the State Geologic Map Compilation geodatabase of Horton and others (2017; https://doi.org/10.3133/ds1052), the World Kimberlites CONSOREM Database (v.3) from Faure (2010; https://www.consorem.ca), and data from Krevor and others (2019; https://doi.org/10.3133/ds414). A 20-km buffer was applied to polygons from all three data sources.
SP3: Failed Rifts
This layer illustrates areas of known, ancient, failed rifts within the United States including the midcontinent rift (MCR), the southern Oklahoma aulacogen (SOA), and the Reelfoot rift (RR). Failed rifts are known to contain iron-rich mafic and ultramafic intrusive rocks which can be hydrogen sources. This layer was created by digitizing the MCA, SOA, and RR from Elling and others (2022; https://doi.org/10.1130/GSATG518A.1). A 20-km buffer and migration pathways were applied to this layer.
SP4: Geophysical Anomalies
This layer illustrates areas where isostatic gravity anomaly data from Kucks (1999; https://mrdata.usgs.gov/gravity) are greater than or equal to 30 mGal. The anomalies may represent subsurface, ultramafic rocks which can be hydrogen sources. Migration pathways were applied to this layer and this layer excludes areas accounted for in SP3: Failed Rifts.
Source: Radiolysis
A process where natural radioactive decay splits water molecules and releases hydrogen gas.
RD1: Uranium Deposits
This layer illustrates areas where uranium deposits are known to be present in the subsurface. This layer was compiled by the USGS from published sources and is retained by the U.S. Energy Information Administration (2020; https://atlas.eia.gov/datasets/eia::uranium-identified-resource-areas/about). Uranium decay is a key component in the radiolysis process. A 10-km buffer and migration pathways were applied to this layer.
RD2: Uranium Favorable
This layer illustrates areas where uranium deposits are favorable to occur in the subsurface. This layer was compiled by the USGS from published sources and is retained by the U.S. Energy Information Administration (2020; https://atlas.eia.gov/datasets/eia::uranium-nure-favorable-areas/about). Uranium decay is a key component in the radiolysis process. A 10-km buffer and migration pathways were applied to this layer.
RD3: Precambrian Craton
This layer illustrates areas that are underlain by the Precambrian cratonic platform defined by Marshak and others (2016; https://doi.org/10.13012/B2IDB-7546972_V1). The Precambrian craton contains Proterozoic-aged granites and granitoids that are enriched in radioactive elements such as uranium and thorium. These elements have long half-lives and rocks within this layer are, therefore, favorable for the radiolysis of water to produce hydrogen. A 100-km gradient was applied to the edge of this layer.
RD4: Accreted Terranes
This layer illustrates areas that are underlain by accreted terranes outside of the Precambrian cratonic platform defined in RD3 by Marshak and others (2016; https://doi.org/10.13012/B2IDB-7546972_V1). These rocks are younger than the cratonic rocks and include areas within the western and eastern American cordillera and southeastern coastal plain. A 100-km gradient was applied to the edge of this layer.
RD5: Young Granites
This layer contains Phanerozoic-age granitic rocks at the surface, and was created by filtering data from the State Geologic Map Compilation (SGMC) geodatabase of Horton and others (2017; https://doi.org/10.3133/ds1052). A 20-km buffer was applied to the polygons in this layer.
Source: Deep/Mantle
Ultra-deep hydrogen can occur within the Earth’s lower crust and mantle at high-temperature, high-pressure conditions.
DP1: Surface Faults
This layer illustrates areas where faults are present at the surface from McCafferty and others (2023; https://doi.org/10.5066/P970GDD5). Faults can connect to and provide pathways for geologic hydrogen to migrate from deep sources into potential reservoirs for storage. A 10-km buffer and migration pathways were applied to this layer.
DP2: Suture Zones
This layer illustrates areas of Paleoproterozoic-age, suture zones, and was created by digitizing lines of interpreted suture zones within the United States from Whitmeyer and Karlstrom (2007; https://doi.org/10.1130/GES00055.1). These areas are interpreted to represent significant, internal crustal boundaries that may promote fluid migration from deep, crustal sources. A 40-km buffer and migration pathways were applied to this layer.
DP3: High Heat Flow
This layer illustrates areas of modeled heat flow greater than 80 mW/m2, and was digitized from Blackwell and others (2011; https://www.smu.edu/-/media/Site/Dedman/Academics/Programs/Geothermal-Lab/Graphics/SMUHeatFlowMap2011_CopyrightVA0001377160_jpg.jpg). Elevated heat flow is connected with hydrothermal fluids which may contain associated hydrogen gas.
Reservoir
Sedimentary (e.g. sandstone, shale, carbonate) or crystalline (e.g. igneous and metamorphic) rocks that contain intergranular or fracture porosity to store hydrogen in the subsurface.
RS1: Sedimentary Rocks
This layer shows areas where sedimentary rocks are present at the surface and was created by filtering data from the State Geologic Map Compilation (SGMC) geodatabase of Horton and others (2017; https://doi.org/10.3133/ds1052). The data were filtered to separate sedimentary rocks (e.g. sandstone, shale, carbonate) from crystalline (e.g. igneous, metamorphic) rocks. Sandstones, carbonates, and other sedimentary rocks contain intra- and intergranular pore space, which can provide storage space for hydrogen.
RS2: Non-Sedimentary Rocks
This layer shows areas where crystalline rocks (non-sedimentary) are present at the surface and was created by filtering data from the State Geologic Map Compilation (SGMC) of Horton and others (2017; https://doi.org/10.3133/ds1052). The data were filtered to separate crystalline rocks (e.g. igneous, metamorphic) from sedimentary rocks (e.g. sandstone, shale, carbonate). Crystalline rocks don’t contain intergranular porosity like sedimentary rocks, but they often contain natural fractures that can provide storage capacity for hydrogen gas.
RS3: Sedimentary Basins
This layer illustrates areas where sedimentary basins are present in the subsurface and was created by digitizing all "sedimentary basin" polygons from Frezon and Finn (1988; https://doi.org/10.3133/om223). Sedimentary basins throughout the United States contain thick (1,000's feet) accumulations of porous rock for potential hydrogen storage.
Seal
Sedimentary (e.g. sandstone, shale, carbonate) or crystalline (e.g. igneous and metamorphic) rocks that contain little to no permeability to retain or seal hydrogen in a subsurface reservoir.
SL1: Salt
This layer illustrates areas where salt is present in the subsurface and was created by digitizing salt polygons from Ege (1985; https://doi.org/10.3133/ofr8528). Salt is a highly impermeable evaporite and is very effective at sealing fluids and gases in the subsurface.
SL2: Sedimentary Rocks
This layer shows areas where sedimentary rocks are present at the surface and was created by filtering data from the State Geologic Map Compilation (SGMC) geodatabase of Horton and others (2017; https://doi.org/10.3133/om223). The data were filtered to separate sedimentary rocks (e.g. sandstone, shale, carbonate) from crystalline (e.g. igneous, metamorphic) rocks. When shales, carbonates, and other sedimentary rocks are compacted or cemented during burial, they lose their porosity and permeability and become effective at sealing potential gas accumulations in the subsurface.
SL3: Non-Sedimentary Rocks
This layer shows areas where crystalline rocks (non-sedimentary) are present at the surface and was created by filtering data from the State Geologic Map Compilation (SGMC) of Horton and others (2017; https://doi.org/10.3133/om223). The data were filtered to separate crystalline rocks (e.g. igneous, metamorphic) from sedimentary rocks (e.g. sandstone, shale, carbonate). Crystalline rocks have little to no permeability and can be effective at sealing potential gas accumulations in the subsurface.
SL4: Sedimentary Basins
This layer illustrates areas where sedimentary basins are present in the subsurface and was created by digitizing all "sedimentary basin" polygons from Frezon and Finn (1988; https://doi.org/10.3133/om223). Sedimentary basins throughout the United States have thick (1,000s of feet) accumulations of low porosity and permeability rock. Thick accumulations of compacted and cemented sedimentary rocks can provide effective seals for gas accumulations in the subsurface.
Results
Hydrogen Prospectivity Map
Final map of geologic hydrogen prospectivity that reflects the weighted combination of the chance of sufficiency of the source, reservoir, and seal components of the hydrogen system.
Total Source Map
Final map of geologic hydrogen source sufficiency that models the chances of having serpentinization, radiolysis, and/or deep hydrogen sources.
Serpentinization Map
Map of areas that are likely to produce serpentinization-type reactions as a source of geologic hydrogen.
Radiolysis Map
Map of areas that are likely to produce radiolysis reactions as a source of geologic hydrogen.
Deep Sources Map
Map of areas that are likely to provide deep sources of geologic hydrogen.
Reservoir Map
Map of areas that are likely to provide subsurface reservoirs to store geologic hydrogen.
Seal Map
Map of areas that are likely to provide subsurface seals to prevent leakage of geologic hydrogen.