Deep beneath our planet’s crust, thousands of kilometers below the surface, scientists believe a vast and unexpected treasure may be hiding: hydrogen. New research suggests that Earth’s core could store enormous amounts of hydrogen, potentially making it the largest hydrogen reservoir on the planet.
A Surprising Source of Hydrogen
For decades, scientists have known that hydrogen is the most abundant element in the universe. However, most discussions about hydrogen on Earth focus on surface sources such as water, fossil fuels, or underground gas deposits. Now, researchers propose that during Earth’s early formation—about 4.5 billion years ago—hydrogen may have bonded with iron and sunk deep into the planet’s core.
The Earth’s core is primarily composed of iron and nickel. Under the immense pressures and temperatures found there, hydrogen could dissolve into molten iron. Laboratory experiments simulating core conditions show that iron can absorb significant amounts of hydrogen, forming iron hydrides. If this process occurred on a planetary scale during Earth’s formation, the core could be storing vast quantities of hydrogen even today.
Clues from Seismic Waves
Scientists cannot drill to the core, but they can “see” it using seismic waves generated by earthquakes. These waves travel at different speeds depending on the materials they pass through. Some researchers believe that unexplained differences in seismic wave behavior could be partly due to hydrogen mixed within the iron-rich core.
This theory may also help explain why the core is slightly less dense than pure iron. The presence of lighter elements, including hydrogen, could account for the density gap observed in geophysical measurements.
Why It Matters
If confirmed, the discovery would reshape our understanding of Earth’s formation and its internal chemistry. It could also influence how scientists think about hydrogen cycles on Earth and even the potential for hydrogen storage on other rocky planets.
While accessing this deep hydrogen is not feasible with current technology, the idea that the planet’s core may hold the largest hydrogen reserve on Earth highlights how much remains unknown about the world beneath our feet.
