백색 수소: 에너지를 변혁할 수 있는 숨겨진 가스

Trillions of tons of hydrogen lie in Earth's crust. Can a Bavarian geologist unlock this clean and cheap energy source?

Deep in a forest in the German state of Bavaria, Jürgen Grötsch fights his way through low-hanging branches. He is heading for a secret location hiding a bounty worth millions. If tapped successfully, it could change clean energy generation around the world. The treasure in question is a rare form of hydrogen that flows naturally from the ground.

Grötsch is a geologist. After decades working for the Dutch fossil fuel giant Shell, he is now a researcher at the German University of Erlangen-Nuremberg. With the help of two of his students, he hammers a meter-deep hole into the ground, inserts a gas sensor and waits for its measuring device to display what's down here. He calls it "sniffing" for hydrogen.

"This is significant," he says as the numbers on the display keep rising. It stops just above 500 parts per million, meaning 0.05 percent of the gas sample is hydrogen. 

"That's 1,000 times more than in the air around us," says Grötsch. For him, it indicates that he's found a hydrogen jackpot in this southern German forest.

For years now, company CEOs and politicians such as the  President of the European Commission Ursula von der Leyen andAustralia's Anthony Albanese have been hailing hydrogen as a way to decarbonize economies.

The gas can be burned to create the intense heat needed to power ships or heavy industries like steel. And unlike oil, gas or coal, it doesn't create planet-heating emissions. The International Energy Agency says global demand could triple by 2050. 

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But there's a catch. Hydrogen needs to be manufactured. And the process of making it relies heavily on fossil fuels. Less than 1% is currently made from renewable energies, in a costly process called electrolysis. 

Grötsch says natural hydrogen, also known as "white hydrogen," could provide a third option. It forms naturally in the Earth's crust, in geological processes billions of years old. 

"Much of the Earth's mantle is iron-rich rock," he says. "When it meets with water at temperatures of 200 to 350 degrees Celsius, the iron basically takes the oxygen from the water, leaving behind pure hydrogen."

This reaction, called serpentinization, is the way most natural hydrogen forms.

Around 5.6 trillion tons of hydrogen are believed to sit in the Earth's crust, according to researchers from the US Geological Survey. Most of it is too deep to reach but getting out just 2% would be enough to cover hydrogen demand for 200 years, the scientists wrote in a 2024 study.

The lightest of all elements, hydrogen can rise from the Earth's mantle towards the surface through cracks. It sometimes leaks into the above-ground world, but most  accumulates in reservoirs of porous stone, like sandstone, trapped beneath layers of more solid rock. 

Dozens of companies around the world are now looking for such reservoirs. But there is only one place, the Bourakebougou village in Mali, where natural hydrogen is already being extracted and used locally to generate electricity. 

The well's output is small, at about 49 tons per year. By comparison, a fossil gas well produces hundreds to thousands of tons over the same period. But it makes a case for the viability of extracting natural hydrogen, thereby bypassing the need to manufacture it.

And at the Mali well, the hydrogen flows with the same pressure as when the facility opened 14 years ago. "Technically it's a renewable source because the processes that produce natural hydrogen are constantly ongoing," says Kate Adie, a subsurface analyst with global energy research firm Wood Mackenzie. As long as the rate of extraction doesn't exceed the rate of formation.

In Bavaria, Jürgen Grötsch plans to sell natural hydrogen for $1 (€0.87) per kilo, similar to the price of hydrogen made from fossil fuels.  

By 2030, he plans to extract 1,000 tons of white hydrogen annually from a Bavarian reservoir 1,500 meters (4,921 feet) below ground. It would be used by local companies and heat networks, which enable centrally produced heat to be distributed to different buildings.

"From the same reservoirs we also want to produce hot water that can be used to heat homes," says Grötsch. This geothermal energy is the economic safety net in case the hydrogen business doesn't work out.

But like many pioneers in the field, Jürgen Grötsch faces a legal problem. Because only a handful of countries officially list white hydrogen as a natural resource, accessing government subsidies and drilling permits is difficult. And that scares investors away.

Apart from a few small exceptions, major oil and gas companies haven't yet invested in the hunt for natural hydrogen. And even Grötsch has yet to secure investment.  

"They sit back and allow the startups to be the pioneers and to de-risk the industry," says Kate Adie. "But once one of these startups can produce a commercially significant amount of natural hydrogen, there'll be a land grab for acreage."

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Wood Mackenzie's best-case scenario is that 20 million tons of natural hydrogen could be produced per year by 2050. That would be 6.7% of the hydrogen needed by then, according to IEA estimates. 

"It is a big adventure," says Grötsch, as he packs up his searching tools in the forest in Bavaria. "We're at a stage where 150 years back, the oil and gas industry was. We are here, starting a new era of the energy industry. Hopefully."

Edited by: Tamsin Walker