Scientists from the University of Grenoble Alpes in France are investigating the discovery of "white hydrogen" in a chromite mine in Albania, claiming it is the largest reserve of natural hydrogen ever recorded.
The discovery is thought to provide clues as to where underground deposits of the clean fuel might be found.
Measuring the gas in a pool almost a kilometer underground, the research team reported that "the bubbling was very intense, just like a hot tub."
The researchers found that more than 80 percent of the gas bubbling up from the pool was a mixture of hydrogen, methane and a small amount of nitrogen. Scientists have measured a hydrogen flow of 11 tons per year at the mine, the highest flow of hydrogen gas ever measured from a single point source anywhere on the Earth's surface.
They landed at the Bulqizë chromite mine in Albania, where hydrogen gas leaking from the rocks has caused many explosions. The mine is also located in an area where an iron-rich rock known as ophiolite is exposed.
In other places, such as Oman, water is known to react with such rocks to produce hydrogen.