White hydrogen, the wildcard of the energy transition

Part II: origins and sources

Photo by Kuba Regulski on Unsplash

This article is part of a series about white hydrogen.

Part one focused on the history of its still incipient exploration. It highlighted the potential white hydrogen has to upend the energy transition. You can read part one here.

Part two will focus on the physical origins of white hydrogen and the current knowledge about its reserves.

First, recapping white hydrogen’s definition: naturally occurring hydrogen on underground deposits (or seeping from the Earth’s crust). White hydrogen has several other names: geologic, native, natural, or golden.

The names seem to reflect different perspectives on hydrogen. Those thinking of hydrogen as fuel name it white or golden. The geological community will use natural, geological, or native. The former wants easy labels to help compare hydrogen production costs between different sources. The latter concentrates on hydrogen’s origin.

Why white hydrogen even exists?

The short answer: no one knows for sure.

The discovery of extensive underground hydrogen deposits seems surprising. The hydrogen molecule H2 joins two hydrogen atoms, the first element in the periodic table. The resulting low density makes H2 very nimble. It effortlessly floats up the atmosphere and off the planet unless it binds to other elements, as in rocks.

Large hydrogen reservoirs seem challenging to explain as fossil leftovers from Earth’s creation time. That hydrogen should have escaped a long time ago. Even today, the idea of existing hydrogen subterranean deposits faces prejudice because of the expectation of its rarity.

From this viewpoint, hydrogen in underground deposits must come from sources that reseparate the hydrogen bound to rocks in the past.

However, some authors entertain that some hydrogen comes from primordial sources deep on Earth.

In 2012, a paper proposed the existence of large hydrogen and helium fields deep on Earth’s crust that provoke earthquakes through explosions. The authors advance that the degassing hydrogen and helium from the liquid core fuels explosions (see figure 1).

Figure 1: Illustration of H2 and He degassing from Earth’s core and mantle (source)

A recent paper found evidence of the relationship between explosions from fluids in the crust and earthquakes.

An extensive review paper from 2020 found over ten different origins proposals for white hydrogen origin. Theories include both abiogenic and biogenic, including microbiological origin.

Besides the prejudice against the existence of white hydrogen and the several hypotheses on its origin, several practical reasons make it difficult to detect:

• It diffuses quickly;
• It reacts quickly with other materials;
• It requires specific detectors and procedures;
• With contact with oxygen, it turns to water;
• Microorganisms consume it;
• Most drilling occurs in sedimentary basins, a more medium adverse for hydrogen presence.

White hydrogen deposits: locations and compositions

Due to the bias mentioned earlier, the current knowledge of white hydrogen reserves shows significant gaps. Figure 2 sums up the results of an extensive 2020 review paper.

Figure 2: Discoveries of white hydrogen (source)

Several white hydrogen sources relate to plate tectonics and volcanic activity, particularly geothermic brines. However, several sources do not, highlighting how much we do not know about white hydrogen origins.

The lack of reserves in certain areas comes more from a lack of studies than the confirmed absence of deposits. For instance, a more recent study published in 2022 reports white hydrogens findings at the North Pyrenean, not indicated in figure 2.

Several reports show discoveries of white hydrogen in very distinct settings. Hydrogen concentrations don’t seem to correlate with specific tectonic, stratigraphic, or lithological contexts.

A partial explanation may come from low-salinity aquifers that entrap hydrogen, carrying it away from its source and surfacing later in fault zones.

More puzzling still, H2 concentrations can vary significantly:

• Between wells 50 cm apart;
• depending on the time of the sample within the same well;
• In synchrony in wells 50 Km apart, suggesting a global phenomenon.

And for all the difficulty in detecting H2, a colorless and odorless gas that quickly dissipates, hydrogen seeping to the surface affects vegetation creating fairy circles. Figure 3 shows an example in Brazil.

Figure 3: Hydrogen outcropping makes a fairy circle in Brazil (source)

Another interesting fact regarding white hydrogen deposits regards their share in the mix with other gases. Hydrogen content can vary from 10% to 98%. Figure 4 summarizes several white hydrogen sources and their hydrogen content compared to CH4 (methane, aka natural gas) and N2 (nitrogen).

Figure 4: Relative proportions of hydrogen, methane and nitrogen, natural hydrogen (source)

Some wells spew other gases. A white hydrogen well in Nebraska mixed 96% hydrogen with helium, a scarcer gas with constrained availability.

The variability of H2 shares in white hydrogen promises variability in its exploration. Most wells will have to filtrate H2 from other gases. Gases other than H2 in white hydrogen wells can have more or less demand. Still, it seems feasible that gases other than H2 will also have a market.

Is white hydrogen fossil or renewable?

As the energy transition progresses, the demand for hydrogen will increase. An estimate calculates white hydrogen can meet 50% of current hydrogen needs. The search for white hydrogen just began. Arguably, the discovery of more white hydrogen sources seems probable in the future.

White hydrogen presents a potential source for a low-cost, low-carbon H2 to power the energy transition. But can we trust it not to deplete?

The fossil fuel terminology may need a reset when addressing white hydrogen. The word fossil today links with oil, natural gas, and coal, which we associate with environmental damage and approaching depletion.

First, the combustion of hydrogen and its use in fuel cells both deliver water. Hydrogen use poses a negligible environmental hazard. It has some security issues with flammability but presents no toxicity, unlike oil or gasoline.

In a worst-case scenario, white hydrogen exploration may affect underground hydrogen-eating bacteria by taking away their food source.

The known reserves of oil, natural gas, and coal have a timespan of decades to centuries with our current use.

White hydrogen resources will probably have longer timespans, although we need more studies to assert. White hydrogen wells seem to replenish. Some proposed pathways for white hydrogen have a biogenic origin, making it renewable.

In addition, hydrogen already seeps to the surface in several cases, regardless of human action, as the fairy circles show.

Finally, the lower prices of white hydrogen can serve as a stepping stone to help propel the energy transition until green hydrogen cost price becomes affordable.

This article is part two in specific series on white hydrogen: you can read part one here. Both pieces are part of a more extensive series on hydrogen and energy you can read here.