The U.S. Geological Survey published the first map of the prospective locations of naturally-occurring geologic H₂ resources in the contiguous U.S., reflecting a systematic analysis of geologic conditions favorable for H₂ that draws on a newly developed methodology.

The map is the first of its kind at continental scale anywhere, showing likely underground areas to explore for geologic H₂. It reveals areas of interest that have the potential to hold accumulations of geologic H₂, including a mid-continent region that covers Kansas, Iowa, Minnesota and Michigan, the Four Corners states of Arizona, Colorado, New Mexico and Utah, the California coast, and areas along the Eastern seaboard.

“For decades, the conventional wisdom was that naturally occurring H₂ did not accumulate in sufficient quantities to be used for energy purposes,” said Sarah Ryker, USGS associate director for energy and minerals. “This map is tantalizing because it shows that several parts of the U.S. could have a subsurface H₂ resource after all.”

In a recent paper, USGS geologists Geoff Ellis and Sarah Gelman estimated the large potential for — and large uncertainty about — the amount of H₂ accumulations in the world. “We calculate the energy content of this estimated recoverable amount of H₂ to be roughly twice the amount of energy in all the proven natural gas reserves on Earth,” Ellis and Gelman wrote in their recent Science Advances paper.

However, the model makes no predictions about how or where this H₂ is distributed in the subsurface.  The authors note that much of it is likely too deep, too far offshore or in accumulations too small to be economically recoverable.  

“We showed there is a significant potential for geologic H₂ as an emerging energy resource.  The next logical step was to find where it might be in the U.S. – and for that, we had to develop a methodology, which we applied first to the lower 48 states,” Gelman said.

The new USGS prospectivity map does just that, assessing which regions have the necessary geological conditions—H₂ sources, reservoir rocks, and seals to trap the gas—for H₂ accumulation. The map assigns relative prospectivity values from 0 to 1, and areas with higher values (deep blue on the map) are more prospective – likelier to contain geologic H₂ accumulations than areas with lower values.

The map, which will continue to be updated as science and exploration progress, is an important first step in understanding a resource with potential to be a significant future energy resource for the U.S.

The USGS has a long history of providing resource assessments for oil and gas and is evaluating potential emerging resources that would enable states, industry and the nation to add to and diversify energy portfolios.

While there remains considerable uncertainty about the extent to which geologic H₂ can contribute to meeting future energy demand, it has the potential to provide low-cost feedstock for critical chemicals and help decarbonize the energy sector.