Capture or disrupt CO2 it should be done carefully, says Stephen Wallace, who runs the Microbiology lab at the University of Edinburgh. But he adds that Cemvita Factory’s idea of using microbes to produce hydrogen is “a sign of the most exciting work going on in medical science right now.” Wallace and his colleagues are also experimenting with bioreactors and have succeeded in getting microorganisms to release hydrogen from things like mold bread or lignin in paper waste.
But while some bacteria help produce hydrogen, others are the bane of these projects, as they can eat stored hydrogen or pollute natural wells, says Jon Gluyas, a geologist at Durham University. “We are trying to prevent bacteria from having our hydrogen because they like to eat it,” he explains.
And he has another problem. He says that “hydrogen gold” is different from what Cemvita Factory wants. For Gluyas, the term refers mainly to hydrogen that is naturally produced underground. He must know. “I named it,” he says. That Cemvita has given the same name to its hydrogen—which, the company clarifies, is “naturally produced, by invisible microbes, by a human-controlled process”—is purely coincidental, says Karimi.
For more than 100 years, geologists have speculated that the natural hydrogen that Gluyas mentions can be found freely beneath our feet. A German scientist, Ernst Erdmann, explained in 1910 how hydrogen was discovered in a salt mine and he searched for it for four and a half years. But the potential for widespread underground sources was still poorly understood, even until the 1980s, says Barbara Sherwood Lollar, a geologist at the University of Toronto.
He remembers the place where he was exploring for gas back then and realized that there were huge volumes of hydrogen in the ground. “Good lord, it was hydrogen, these rocks were full of hydrogen,” he remembers. Yes, the Earth has bubbles. Since then, he and his colleagues have mapped potential hydrogen sources—based on geology and known deposits—around the world.
Different processes can create natural hydrogen reservoirs. One example is radiolysis, in which particles from naturally occurring radioactive rocks such as granite cause other molecules to split apart, releasing hydrogen. In general, hydrogen is associated with crystalline rocks, not sedimentary.
But as Gluyas points out, microbes often release the hydrogen produced in the soil before anyone has a chance to absorb it. So the tricky part is finding an underground hydrogen source that is large and stable. “No one, I think, can say that hydrogen is in crystalline rocks or not… it would be possible,” says Sherwood Lollar.
Some companies are already targeting hydrogen deposits, though – like Australia’s Gold Hydrogen company. It is estimated that there may be 1.3 billion kilograms of hydrogen at a depth of around 500 meters in the Ramsay Peninsula and Kangaroo Island in South Australia. There is also a large and well-known source of hydrogen in Mali. Both of these places and the Australian one are associated with “spinning circles”—where the empty spots between the plants indicate that hydrogen is escaping from the ground. Hydrogen production from any such source, on a large scale, has yet to occur.