By Prof. Bolaji Aluko Ph.D
In energy-talk, the “color” of hydrogen is not ROYGBIV, but a shorthand for how the hydrogen was made, and how clean it is.
Here is how it breaks down:
1. *Green hydrogen*
*Made by*: Electrolysis of water using electricity from renewables like solar, wind, hydro.
*Carbon footprint*: Near zero. This is the “true” renewable/green version.
*Why it matters*: No CO₂ emitted during production. The main barrier is cost and energy use.
2. *Blue hydrogen*
*Made by*: Steam reforming of natural gas, but with carbon capture and storage for most of the CO₂.
*Carbon footprint*: Low, but not zero. Some methane leakage and capture isn’t 100%.
*Why it matters*: Cheaper than green right now, used as a bridge fuel.
3. *Grey hydrogen*
*Made by*: Steam reforming of natural gas with no carbon capture.
*Carbon footprint*: High. This is ∼95% of hydrogen produced today.
*Why it matters*: Cheap and established, but not renewable or clean.
4. *Other colors you’ll see*
– *Brown/Black*: Made from coal gasification. Highest emissions.
– *Yellow*: Electrolysis using grid electricity, which may have a mix of fossil and renewables.
– *Pink/Red*: Electrolysis using nuclear power.
– *Turquoise*: Made by methane pyrolysis, producing solid carbon instead of CO₂ gas. Still experimental.
– *White*: Naturally occurring hydrogen found in geological deposits.
*So for “renewable energy source”*:
Only *green hydrogen* qualifies as fully renewable. It’s made with renewable electricity and water, and the only byproduct is O₂.
The EU, US, and most policy frameworks define “renewable hydrogen” as green hydrogen with strict limits on lifecycle emissions.
Natural Hydrogen Deposits on Earth – Nigeria?
Natural hydrogen deposits, also called “white” or “gold” hydrogen, have been found in many places.
1. *Nigeria*
There’s no major publicized discovery yet, but Nigeria is on the exploration map. So no confirmed commercial deposit in Nigeria yet.
2. The geology in parts of West Africa is similar to Mali’s Bourakébougou basin, where the world’s first commercial natural hydrogen well has been producing since 2012. The US Geological Survey and others flag the West African craton as prospective for serpentinization-generated H₂.
3. *France*
France has one of the biggest confirmed finds so far:
– *Lorraine region, Folschviller*: In 2023 researchers from CNRS and GeoRessources found a deposit estimated at 46-260 million metric tons of white hydrogen at ∼1,250 m depth. That’s more than half of global annual grey hydrogen production. Concentration hit 20% at 1,250 m, and models suggest it could reach 98% at 3,000 m.
– *Pyrenees/Alps*: New research from 2026 points to the Alps and Pyrenees as prime targets due to serpentinization of mantle rocks brought up during mountain building. The Mauléon Basin in SW France is called a “prime natural H₂ exploration area”.
4. Confirmed/producing countries:*
– *Mali*: Bourakébougou – 98% pure H₂, used to power a village since 2012.
– *Albania*: Bulqizë chromite mine – measured flow of 11 tonnes/year, >80% H₂. Estimated reservoir of 5,000-50,000 tonnes.
– *Turkey*: Chimaera seep – has been seeping H₂ since antiquity.
– *Australia*: Kangaroo Island wells in the 1920s-30s produced up to 84% hydrogen. Active exploration in South Australia now.
– *Tanzania*: Rukwa basin – natural H₂ and helium found in 2024.
*Active exploration:*
– *US*: USGS mapped 30+ states with high prospectivity, especially the Midcontinent Rift running through Nebraska, Kansas, Arizona. Bill Gates-backed Koloma is drilling there.
– *Spain*: Pyrenees, plus other ophiolite zones.
– *Canada, Colombia, Finland, Korea, Morocco, Brazil*.
– *Russia*: Discovery in 2008 suggested native H₂ in geological environments.
– *Oman, New Caledonia*: Ophiolite belts known for serpentinization.
Why it matters
Most of Earth’s H₂ is thought to form by serpentinization – water reacting with iron-rich mantle rocks. Estimates are ∼5.6 trillion metric tons trapped in the crust, with 15-31 million tons generated yearly. Even 1% recovery could cover global H₂ demand for hundreds of years.
We are still figuring out how much actually accumulates in economic reservoirs. Most oil/gas wells never looked for it.
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Bolaji Aluko
May 2026
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