Earth's hidden hydrogen reserves could replace fossil fuels for centuries, study finds

Recent research reveals that Earth may hold an estimated 6.2 trillion tons of hydrogen gas in underground rocks and reservoirs, potentially offering a clean energy source capable of replacing fossil fuels for centuries. It is estimated that even 2% of the discovered hydrogen—around 124 billion tons—could meet global energy needs for 200 years, helping achieve net-zero carbon emissions.

This vast hydrogen reserve is approximately 26 times the weight of known oil reserves. As an article by the Live Science publication points out, though, its precise location remains unclear, and significant portions may be too deep, far offshore, or economically unfeasible to extract.

Hydrogen is a versatile, clean energy source that can power vehicles, industrial processes, and electricity generation. Hydrogen forms naturally in Earth's crust through chemical reactions involving rocks and water. Previously, scientists believed hydrogen molecules were too small to accumulate underground, easily escaping through pores and cracks in rocks. This perspective changed after significant hydrogen discoveries in West Africa and an Albanian chromium mine demonstrated that the gas can collect in underground reservoirs.

The new findings suggest that hydrogen deposits could be widespread and substantial.

To estimate the total hydrogen reserves, researchers developed a model that considered production rates, reservoir trapping, and natural leakage. While the model’s most probable estimate is 6.2 trillion tons, the range is broad, from 1 billion to 10 trillion tons, underscoring significant uncertainty. These findings were published in Science Advances on December 13, 2024.

Natural hydrogen has distinct advantages over its artificially produced counterparts. Current methods of hydrogen production involve either the electrolysis of water with renewable energy (producing "green hydrogen") or fossil fuels (producing "blue hydrogen"). Both require energy inputs and storage solutions. In contrast, natural hydrogen exists underground, requiring no additional energy to produce, and can remain stored in reservoirs until needed. According to Geoffrey Ellis, the study's lead author and a petroleum geochemist with the U.S. Geological Survey, "You could just open a valve and close it whenever you needed it."

Hydrogen demand is expected to rise fivefold by 2050, with the gas projected to supply up to 30% of the energy needs in some sectors. Green hydrogen also makes up a key element in Azerbaijan's energy strategy, aiming to diversify its energy export portfolio and promote its decarbonisation policy. As researchers identify geological criteria for hydrogen accumulation, pinpointing accessible reserves will be key. This effort is underway, with results for potential U.S. hydrogen deposits anticipated next year.

Despite the promise of natural hydrogen, challenges remain. Much of the hydrogen may be located in inaccessible or uneconomical sites, and precise mapping is required to determine viable reserves. However, if the technology and methods for extraction improve, natural hydrogen could revolutionize energy systems by offering a plentiful, clean alternative to fossil fuels while avoiding storage and production challenges associated with artificial hydrogen.

By Nazrin Sadigova