Most of the hydrogen on Earth exists in water and organic compounds. Known occurrences of natural hydrogen are rare, partly because we haven’t looked very hard due to preconceived opinions that are probably wrong.
Major uses of hydrogen are upgrading bitumen and heavy oil, and removal of sulphur from liquid petroleum. The use of hydrogen for lighter than air transportation was abandoned in 1937 after the dirigible Hindenburg caught fire. There are 1000s of other commercial uses in food preparation, plastics, and petrochemicals.
Hydrogen may be the wave of the future for powering land transportation and industry in the “Hydrogen Economy” – think 2050 or beyond. There are many unresolved technical and practical issues. The virtue of such a fuel is that the exhaust is water (and maybe some NOx) instead of CO2, which contributes to climate change. The exhaust water would have to be captured on the vehicle since that huge amount of water would have its own local climatic effects and would make roads totally useless at temperatures below freezing. Foreseeable but ignored consequences abound.
Petrophysics, with other geosciences, can play
a role in finding and evaluating new naturally occurring hydrogen
resources. Current production is by reforming of methane,
electrolysis of water, or pyrolysis of methane. Petrophysics will
play a major role in locating these raw materials if the hydrogen
economy actually takes off.
It might be better to electrify transport and use heat pumps for HVAC, and avoid the H2 middleman. This leaves about 40% of current carbon emissions to be fixed – the carbon-heavy industrial heartland to decarbonize with Green Hydrogen. As hydrogen technology improves, the timing might just work out for all those 2050 targets that governments have made.
Another large source is as a byproduct of the manufacture of ammonia, methanol, and other industrial chemicals. A tiny fraction is from electrolysis of water or pyrolysis of methane.
The 2015 discovery of naturally occurring hydrogen in Mali has broadened the search for clean green sources.
FROM METHANE USING STEAM REFORMING
This reaction is favoured at low pressures but is usually conducted at high pressures (2.0 MPa). This is because high pressure H2 is the most marketable product, and pressure swing adsorption (PSA) purification systems work better at higher pressures. The product mixture is known as "synthesis gas" because it is often used directly for the production of methanol and related compounds.
HYDROGEN PRODUCTION FROM ELECTROLYSIS OF WATER
The method presumes that an adequate supply of unallocated fresh water, (or desalinated sea water or medium, depth oilfield brine) and a source of unallocated electricity can be found. In many areas, fresh water is already in short supply and additional draws on surface or near surface water may be impossible. Deeper sources may also be restricted. See “Analyzing Water Wells” to learn how to locate potential underground sources of water.
The chemistry electrolysis is pretty simple:
Theoretical efficiency (electricity used vs. energetic value of hydrogen produced) is between 88 – 94% with no impurities in the water, much less if desalinization is needed. Energy cost of co compression, storage, and transportation to market are also not included3.
HYDROGEN PRODUCTION FROM METHANE PYROLYSIS
Pyrolysis is achieved by having methane (CH4) bubbled up through a molten metal catalyst containing dissolved nickel at 1,070 C. This causes the methane to break down into hydrogen gas and solid carbon, with no other byproducts (except those from maintaining the reactor at the high temperature required).
The chemistry is deceptively simple, but
implementation is tricky.
The industrial-quality solid carbon may be sold as manufacturing feedstock or permanently landfilled, it is not released into the atmosphere and there is no ground water pollution in the landfill.
Methane pyrolysis is in development and considered suitable for commercial bulk hydrogen production, assuming low cost methane is available as both feedstock and heat source. Further research continues in several laboratories and at least one pilot project.
NATIVE HYDROGEN FROM RESERVOIR
Discovered in 2015 while drilling for water, natural hydrogen blew out with the artesian water. Analysis of the well Bougou-1 found the gas had a concentration of 98% pure hydrogen, with traces of methane, nitrogen, and helium. This is the purest naturally occurring hydrogen ever discovered.
Further exploratory wells were drilled and analyzed, including two 2500 meter fully cored stratigraphic holes, resulting in a second natural hydrogen gas field.
The hydrogen is trapped in 5 reservoir layers, each sealed by a lava flow. The hydrogen molecule is so small, it is possible that only unfractured igneous or evaporite minerals can form the impermeable seal needed for hydrogen.
This is where petrophysics cones to the rescue. Take a peak under the rug and see what might be waiting below all those salts, anhydrites, and volcanics you drilled through over the last 70 years. No, it won’t be that easy as you probably need a deep-seated source and a migration path – well logs can help there too.
It’s time for a paradigm shift for hydrogen!
Some scientists believe gas generation will continue for thousands of years, sustainably decarbonising the local community (who did not have much of a carbon footprint to begin with. This is highly speculative as it may have taken millions of years for the gas to migrate and accumulate from deep source rocks to these reservoirs. There are at least 7 possible mechanisms for the generation of hydrogen discussed in the reference paper.
FROM SERPENTINIZATION REACTIONS
Serpentinization is a form of low temperature
metamorphism driven largely by hydration and oxidation of olivine
and pyroxene, creating serpentine minerals brucite, and magnetite.
Under the unusual chemical conditions accompanying serpentinization,
water is the oxidizing agent, and is itself reduced to hydrogen.
This leads to further reactions that produce rare iron group native
element minerals, such as awaruite and native iron, methane, and
other hydrocarbon compounds, and hydrogen sulphide.
Hydrogen is produced during the process of
serpentinization. In this process, water protons (H+) are reduced by
ferrous (Fe2+) ions provided by fayalite (Fe2SiO4). The reaction
forms magnetite (Fe3O4), quartz (SiO2), and hydrogen (H2).
Laboratory studies of serpentinization at high
temperature and pressure show how methane could be produced, lending
some credence to deep-seated gas and oil generation and migration.
My 1954 grade 9 chemistry class didn’t get much past 2H2 + O2 → 2 H2O, but equation 6 looks OK to me.
Ocean seeps show both hydrogen and methane
emissions. We just have to find them onshore, complete with
reservoir and seal, as in the Mali example. There are more than 100
published reports of natural hydrogen seeps on land in a dozen
countries, treated as curiosities across many years. Maybe they will
lead to a new industry, just as the oil seeps of antiquity did.
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