Naturally occurring “white hydrogen” lies in vast reservoirs beneath our feet – now the gold rush of the clean energy era is beginning.
Investors had lost faith in Edwin Drake’s obsessive hunt for oil when the American entrepreneur finally struck black gold in an underground reservoir in Titusville, Pennsylvania, in 1859. The discovery spurred an exploration frenzy that launched the modern oil age. Now, a new generation of wildcatters are racing to replicate that Titusville moment, hoping to bring about the dawn of a major new energy resource. However, it’s not fossil fuels they are looking for, but a commercially viable source of natural – and low-carbon – hydrogen.
Hydrogen, the smallest, simplest and lightest molecule on Earth, is currently used mainly for refining and chemical industries, such as producing ammonia for fertilisers. The vast majority of this hydrogen is made from polluting methane gas or coal gasification.
But there are already other, lower-carbon ways to produce hydrogen. And hydrogen’s ability to store three times more energy than oil, while only producing water when burnt, has made some view it as an attractive clean fuel option, especially for industries which are hard to decarbonise by electrification, such as aviation, shipping or steel production.
“Green” hydrogen, for example, is a cleaner alternative made by splitting water between hydrogen and oxygen molecules in a process powered by renewable energy. “Blue” hydrogen, made from fossil fuels using carbon capture and storage to reduce the emissions, is another alternative.
Green and blue hydrogen have received huge attention as potential low-carbon fuels in recent years, but they also have significant downsides. Both are expensive and faced challenges and delays in their rollout. And while their use is slowly growing, together they still only make up around 1% of global hydrogen production. Some researchers have also raised doubts over how low-carbon blue hydrogen really is due to associated leaks of methane – a potent greenhouse gas which is 80 times more powerful than carbon dioxide (CO2) over a 20-year time span.
Meanwhile, in recent years scientists have found that naturally occurring hydrogen is actually much more widespread than previously thought, leading some to believe it could be tapped as a cheap and carbon-free fuel.
This “geologic” hydrogen, also called natural or white hydrogen, is produced naturally when underground water encounters iron-rich rocks in a process known as serpentinisation. Because hydrogen is so light, it usually seeps through porous rocks and cracks, eventually rising to the atmosphere. That’s if it isn’t first consumed in underground reactions or eaten by subterranean microbes.
But in some geological settings, hydrogen can become trapped under rocks with low permeability, such as salt or shale rocks, which create a seal under which the gas can accumulate. It’s these hydrogen accumulations in the Earth’s subsurface that prospectors hope may be viable for commercial exploitation.
According to a 2024 study from the US Geological Survey (USGS), there could be anywhere between one billion and 10 trillion tonnes of hydrogen in the subsurface, with a best guess of around 5.6 trillion tonnes trapped in geological formations. (BBC)
Most of this hydrogen is likely to be “in accumulations that are too deep, too far offshore, or too small to be economically recovered”, the study’s authors, USGS geologists Geoffrey Ellis and Sarah Gelman, wrote. However, if just 2% of this white hydrogen was recoverable, it could meet projected global hydrogen demand for around 200 years, they found. It would also, they added, contain roughly twice as much energy as is stored in all the proven natural gas reserves on Earth. The idea has sparked huge interest in what could be lying under our feet. At least 60 companies have publicly said they are exploring for white hydrogen, with investment estimated to have reached $1bn (£740m), says Eric Gaucher, a French geochemist who co-leads a white hydrogen expert group convened by the International Energy Agency (IEA). (BBC)
The precious ‘white gold’ fuel buried in the Earth
