- White hydrogen refers to naturally occurring hydrogen gas (H₂) found in the Earth’s crust or subsurface, without any industrial processing. Unlike other types of hydrogen—such as green, blue, or grey hydrogen—that are produced through artificial processes, white hydrogen is geologic hydrogen that exists in its elemental form naturally underground. It can accumulate in rock formations, underground reservoirs, or be released from serpentinization, radiolysis, or other natural geochemical reactions involving water and certain types of rocks, such as iron-rich minerals.
- The term “white hydrogen” is part of the hydrogen color code system, which categorizes hydrogen based on its source and production method. In this context, white hydrogen is the only type that does not involve human intervention for its formation. It is sometimes also referred to as natural hydrogen, gold hydrogen, or geologic hydrogen, though the naming conventions are still evolving in the scientific and energy communities.
- White hydrogen has gained attention in recent years as a potentially abundant, low-cost, and carbon-free energy resource. Since it is not created through fossil fuel combustion or electrolysis, it bypasses many of the environmental and economic barriers associated with synthetic hydrogen production. If large, accessible reservoirs of white hydrogen can be identified and tapped, it could become a game-changer for the global transition to clean energy.
- One key area of interest is the process of serpentinization, where ultramafic rocks (rich in iron and magnesium) react with water to produce hydrogen gas. This reaction can occur naturally over long geological timescales, often deep underground. Hydrogen can also be released by radiolysis, in which radioactive decay splits water molecules, liberating hydrogen. These processes are believed to occur in mid-ocean ridges, ancient cratons, and continental shields, among other geological settings.
- Currently, white hydrogen is still in the early stages of exploration. In recent years, natural hydrogen seeps have been documented in various parts of the world, including France, Mali, Australia, Russia, and the United States. The discovery of a spontaneously emitting hydrogen source in Bourakébougou, Mali, in the 1980s, and the successful use of that hydrogen to power a village, served as a major catalyst for global interest in this resource. More recently, exploratory drilling and geophysical studies have been launched in several countries to assess the feasibility of scaling up natural hydrogen extraction.
- Despite its promise, there are significant technical, economic, and geological challenges to overcome. These include identifying commercially viable reservoirs, developing safe and efficient extraction technologies, and understanding how to store, transport, and integrate this hydrogen into existing energy systems. There are also regulatory and classification questions, since white hydrogen is not yet fully addressed in many countries’ energy policies or resource codes.
