MAPPING PROSPECTIVE REGIONS FOR NATURAL HYDROGEN RESOURCES IN THE US

Energy policy analysts predict an expanded role for hydrogen (H₂) in the future energy supply, with H₂ projected to account for as much as 30% of the energy supply in some sectors and demand increasing more than five-fold by 2050. To achieve climate objectives, these projections involve methane derived H₂ coupled with carbon sequestration (blue H₂), or 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. Currently, H₂ is viewed exclusively as a medium for energy storage and transport and not a primary energy resource.

Although the presence of natural H₂ in the subsurface of the Earth is well documented in a variety of geologic environments, economic accumulations of natural H₂ have generally been assumed to be non-existent. Recent discoveries in Africa and elsewhere have challenged this notion, and there is a growing acknowledgement that geoscientists have not looked for native H₂ in the right places with the right tools. While much is known about the occurrence of subsurface H₂ (e.g., generation mechanisms, consumptive processes, etc.), there is currently a lack of understanding of the processes and settings that are most conducive to the formation of significant accumulations of H₂. To develop effective strategies for exploration and assessment of geologic H₂ resources, a comprehensive framework is required that could lead to discovery of economic H₂ accumulations.

The US Geological Survey is currently working to develop a “hydrogen system” model for the generation of economic accumulations of H₂ resources in the Earth’s subsurface based on the “petroleum systems” concept. The critical elements that make up the models (e.g., source, migration pathway, reservoir, seals, etc.) are the same but the details of each of the elements vary. Given our nascent understanding of geologic H₂, many elements of the H₂ system have a high degree of uncertainty associated with them. Each of the critical elements of the model is being mapped to the geology of the conterminous US to determine the most prospective regions for discovery of geologic H₂ resources. The areas of the uncertainty related to the critical elements are being used to assign risk to prospective regions. Project progress will be presented.