American Association for the Advancement of Science

Hydrogen occurring naturally in the Earth's crust and mantle, produced through inorganic chemical reactions rather than from fossil fuels. It is extracted directly from the ground without requiring energy-intensive production processes.

Hydrogen produced from renewable electricity sources, considered a critical component for hydrogen's long-term credibility as a clean fuel.

A technology that combines hydrogen and oxygen in a clean, electrochemical process to generate power, releasing only water vapor as a byproduct.

Missouri

Colorado

An unpublished research project estimating global subterranean hydrogen reserves at 5 trillion tonnes. Led by Geoffrey Ellis.

Natural hydrogen extraction and utilization for electricity generation in the village of Bourakébougou, Mali. Operating since 2012 with nearly pure hydrogen.

A natural hydrogen extraction initiative at the Bulqize chrome mine in northeastern Albania, transitioning the site from traditional chrome mining to hydrogen energy production.