A hidden source of clean energy could power the planet for more than a hundred thousand years if tapped into, according to new research.

Sources of hydrogen could be hiding amid the Earth's crust -- enough to power Earth at its current energy needs for the next 170,000 years, according to a paper published in Nature Reviews Earth & Environment on Wednesday.

The concept of using hydrogen as renewable energy isn't new, but so far only 0.1% of the hydrogen power is considered "green," or produced in a "climate-neutral" way, according to the World Economic Forum. Hydrogen today is produced using thermal processes of steam and hydrocarbon, the byproduct of which contributes to 2.4% of global carbon dioxide (CO2) emissions, the researchers said in a University of Oxford press release.

There are likely "hydrogen systems" buried beneath continents all over the world, including in at least 30 U.S. states, according to the paper. The hydrogen gas has been building within the Earth's crust for the past billion years, the researchers said.

The researchers developed an "exploration recipe" to assess where the hydrogen reservoirs could be as well as where it would make the most economic sense to feasibly extract them.

"We have successfully developed an exploration strategy for helium and a similar 'first principles' approach can be taken for hydrogen," said Jon Gluyas, chair of geoenergy, carbon capture & storage at Durham University in England and co-author of the study, in a statement.

The "geological ingredients" required for potential extraction sites are ample supplies of the gas itself, reservoir rocks and a geologic formation that prevents the hydrogen from escaping into the atmosphere, the researchers said.

"We know for example that underground microbes readily feast on hydrogen," said Barbara Sherwood Lollar, professor of earth sciences at the University of Toronto in Canada, in a statement. "Avoiding environments that bring them into contact with the hydrogen is important in preserving hydrogen in economic accumulations."

The exploration recipe to find accumulated hydrogen is "likened to cooking a soufflé," said Chris Ballentine, chair of geochemistry at Oxford University and lead author of the paper, in a statement.

"Get any one of the ingredients, amounts, timing, or temperature wrong and you will be disappointed," Ballentine said.

The researchers believe that "one successful exploration recipe" that can be repeated will unlock a commercially competitive, sustainable hydrogen source that could significantly contribute to energy transition, Ballentine said.

Conversely, the research shows that other sources of hydrogen gas, such as from the Earth's mantle, are not viable sources of hydrogen, despite much speculation, the researchers said.

"We have the right experience to combine these ingredients and find that recipe," he said.

A reliable supply of hydrogen is vital for the function of a modern world, the researchers said. Fertilizer used for agriculture is produced by hydrogen, and the gas also serves as a "key energy component" to a carbon-neutral future, the researchers said.

Global demand for hydrogen reached 97 million tons in 2023, but by 2050 demand is expected to increase to 540 tons, the researchers said.

Production followed by the burial of CO2 waste or from renewable energy sources -- such as wind or solar -- could also be future sources of hydrogen, the researchers said.