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