Monday, 7 July, 2025/ Edition 66

Carbon sequestration and hydrogen are usually treated as having separate technologies, but two recent studies suggest intersections and possible integration of these fields. Let’s take a look.

Rasoul Sorkhabi

Editor, Core Elements

Integrating CCS into Hydrogen Production

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Nearly 95 percent of hydrogen is produced from fossil fuels. An article in Energy discusses how carbon capture and sequestration (CCS) could be incorporated into the current hydrogen industry.

Hydrogen colors: Various types of hydrogen production have been color coded. Of these, a few are related to fossil fuels:

• Grey hydrogen is produced from methane without CCS.

• Black or brown hydrogen is produced from coal without CCS.

• Blue hydrogen is produced from methane or coal with CCS.

By the numbers:

• In 2024, global hydrogen production stood at 97 million tons. Less than 1 percent included CCS.

• In 2023, 16 hydrogen production facilities were equipped with CCS technologies, capable of capturing about 11 million tons of CO₂. Most of these facilities were retrofitted refineries and fertilizer plants.

• Global hydrogen production is projected to reach 150 million tons by 2030.

Methods of hydrogen production from fossil fuels:

1. Steam methane reforming (SMR): Reaction of steam and natural gas at temperatures above 800 degrees Celsius

2. Partial oxidation of methane generating hydrogen and CO₂

3. Autothermal reforming: Reaction with water and oxygen

4. Carbon dioxide reforming: Reaction of methane with CO₂

5. Plasma reforming: Ionization of methane

6. Pyrolysis: Thermal decomposition of hydrocarbons into carbon and hydrogen

7. Coal gasification: Reaction of coal with steam, producing CO and hydrogen

CCS can be applied to methods 1, 2, 3, 6, and 7. Method 4 is particularly interesting because the reaction uses two greenhouse gases: Methane and CO₂.

Techno-economic analysis:

• Of the seven methods mentioned above, SMR is most widely used. It is ten to 34 percent more efficient than other techniques.

• Integrating CCS with hydrogen production methods will increase the price of hydrogen by 25–30 percent.

• Production costs for blue hydrogen range from $1.20–2.10 per kilogram of hydrogen, compared with $0.70–1.60 per kilogram of grey hydrogen.

Opportunities and challenges:

• There is huge potential to apply CCS to current hydrogen production processes from fossil fuels.

• The captured carbon can be stored in underground reservoirs, mineralized, utilized as raw material to produce chemicals, or used as supercritical CO₂ for power generation.

• Demand for hydrogen, lower-cost tech for CCS, reduced natural gas prices, more CO₂ pipelines, and updated policies all play roles in integrating CCS with hydrogen production from fossil fuels.

Go deeper: Read the full article here.

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How Mineralization in Mafic and Ultramafic Rocks Could be Valuable in Hydrogen Production

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Mineralization in mafic and ultramafic rocks is one of the ways to sequester carbon dioxide. An experimental study published in the International Journal of Hydrogen Energy suggests that this process may even produce valuable hydrogen.

CO₂ mineralization in basalt: Even though ultramafic rocks have more mafic (higher content of magnesium and iron), basalt has more permeability.

Study design:

• Researchers used basalt samples from the Al-Madinah volcano in Saudi Arabia. This alkali-olivine volcanic rock erupted in 1256.

• They conducted two controlled experiments in parallel: One with nitrogen saturation in the reactor and the other without CO₂ to isolate the effects of CO₂ in the reaction process.

  • They used nitrogen and CO₂ with purities of 99.99 percent and filtered deionized water. 

• Study parameters included:

  • Two temperature conditions: One at 323 degrees Kelvin and the second at 373 degrees Kelvin

  • Two periods: Five days and ten days

  • The initial reactor pressure was kept at five megapascal.

• Gas analysis was performed via gas chromatography.

• Researchers performed detailed pre- and post-experimental mineralogical analyses using XRF and XRD.

 What they found:

• The experiments demonstrated the generation of hydrogen in the collected gas:

  • 0.072 percent for temperature condition of 323 degrees Kelvin for five days

  • 0.08 percent for temperature condition of 323 degrees Kelvin for ten days

  • 0.186 percent for temperature condition of 373 degrees Kelvin for five days

  • 0.197 percent for temperature condition of 373 degrees Kelvin for ten days

• Post-experimental mineralogy showed a considerable increase in carbonate minerals in the sample.

• The initial pressure of five megapascal in the reactor dropped to 4.95 megapascal after five days and 4.90 megapascal after ten days, indicating CO₂ mineralization.

• Total inorganic carbon increased from the baseline of 20.9 milligrams per liter to 46.3 milligram per liter for the 323 degrees Kelvin condition and to 468 milligram per liter for the 373 degrees Kelvin condition.

• The pH decreases during the experiment confirmed the theoretical pathway from carbonic acid formation to carbonate precipitation.

Why it matters: The experiment showed that, not only was the injected CO₂ mineralized, but the reaction also produced free hydrogen.

What’s next? Similar controlled experiments using various mafic and ultramafic rock samples need to be performed to better characterize these processes.

Go deeper: Read the full article here.

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✉️ To get in touch with Rasoul, send an email to editorial@aapg.org.