In some countries, strange circular areas can be seen where, compared to their surroundings, vegetation is much less dense or even non-existent. Even today no one has come up with a convincing explanation for their origin and so these so-called “fairy circles” are often associated with stories and legends. Surprisingly, a lot of these circles are also the site of hydrogen gas emissions, which means that this gas that we manufacture using various processes as part of the energy transition is actually naturally present below ground.
For a long time, the existence of these sources of hydrogen was purely anecdotal, however it is gradually coming into the limelight with the deve-lopment of new projects that are trying to unders-tand how natural hydrogen is formed. And what if this natural resource was much more wides-pread than we had imagined and above all exploi-table? After all, this is only the start, and our investigations are at the same point today as they were 160 years ago for oil and gas. Once they had got over the surprise of seeing hydrogen leaking out of the ground, geologists began to take a closer look, in particular along the Mid-Ocean Ridge where the oceanic crust is for-med. The first assessment of the quantity emitted is stupefying: several tens of millions of tonnes of hydrogen per year! The observation is the same on land: measurements (often taken in the vici-nity of fairy circles) confirm that hydrogen is released in considerable quantities. To find out more and quantify these emis-sions, ENGIE has developed a permanent moni-toring system, PARHyS (Permanent Analyses of Renewable Hydrogen with Sensors). Around 100 of these detectors were recently deployed for a several month period in the São Francisco basin in Brazil (see box below). They revealed flows in the range of 1,000 m3 per day, in other words around 10 tonnes per year.
A CONTINUOUS FLOW OF HYDROGEN
PARHyS (Permanent Analyses of Renewable Hydrogen with Sensors) are small, resilient and affordable detectors that are easy to install, capable of collecting real-time data on hydrogen flows and transmitting this data remotely. Hopefully they will allow us to better understand the underground production of hydrogen and its potential.