Between 1 billion and 10 quadrillion tonnes of natural hydrogen may be stored underground around the world, geologists with the US Geological Survey say in a new study.

Geologists Geoffrey Ellis and Sarah Gelman used a stochastic model to predict the potential amount of hydrogen stored in the Earth’s subsurface. They used averages to find the most likely value to be around 5.6 trillion tonnes. However, they acknowledge that the estimate is only for “natural hydrogen potentially stored in accumulations in the subsurface.”

Moreover, most of this natural hydrogen would be “impractical to recover,” notes the study seen by Kallanish. That said, the researchers highlight that recovering even just 2% of natural hydrogen stored underground can meet the projected hydrogen demand for around two centuries.

“The global demand for hydrogen is projected to reach around 500 million tonnes/year by 2050, and recovery of just 2% of the estimated most probable in-place resource would meet the entire projected global hydrogen demand for around 200 years,” it adds. “This amount of hydrogen contains more energy than all proven natural gas reserves on Earth.”

“Exploration for geologic hydrogen will likely proceed slowly at first since new concepts for the geologic hydrogen system and prospect definition are still being developed,” the researchers continue. “However, as this system is better understood through research, development, and prospect testing, production of geologic hydrogen will likely accelerate.”

Because of its potential to be a cheaper alternative to green and blue hydrogen, exploration for natural hydrogen is currently underway in many locations globally. However, a report by the Oxford Institute for Energy Studies (OIES) released in September said the role of natural hydrogen in achieving net zero was a “low-probability, high-impact scenario” due to the uncertainties around its origination and accumulation mechanism.