Brown Hydrogen and Black Hydrogen refer to hydrogen gas produced through coal or lignite gasification, one of the earliest and most established hydrogen production technologies.
Black Hydrogen is produced from bituminous or hard coal, while Brown Hydrogen is derived from lignite (brown coal). In both cases, coal reacts with oxygen and steam at high temperatures to form synthesis gas (syngas), from which hydrogen is separated and purified.
This production pathway offers high reliability, large-scale output, and low production cost, but also has the highest carbon footprint among all hydrogen types unless integrated with Carbon Capture, Utilisation & Storage (CCUS).
Production Technology
Coal / Lignite Gasification
Coal is crushed, dried, and gasified with oxygen and steam at 900–1,200°C, producing syngas containing hydrogen, carbon monoxide, carbon dioxide, methane, and sulfur compounds.
Water-Gas Shift Reaction
CO + H₂O → CO₂ + H₂
This reaction maximizes hydrogen yield.
Gas Cleaning & Purification
Acid gas removal (CO₂, H₂S) followed by PSA or membrane separation produces industrial-grade to ultra-high-purity hydrogen.
Carbon Capture Integration (Optional)
CO₂ can be captured at pre-combustion or shift-reaction stages, reducing carbon intensity and enabling “low-carbon coal hydrogen.”
Key Characteristics
Fossil-Based Origin
Entirely derived from coal or lignite, offering energy security in coal-rich regions.
High Carbon Intensity
CO₂ emissions: ~18–20 kg CO₂ per kg of hydrogen
Requires CCUS to meet climate targets.
Cost Advantage
Among the lowest-cost hydrogen production routes with mature infrastructure.
Reliable Baseload Production
Operates continuously, independent of weather or renewable availability.
Physical & Chemical Properties
| Property | Value | Significance |
|---|---|---|
| Molecular Formula | H₂ | Pure hydrogen |
| Purity Range | 95–99.999% | Depends on purification |
| Density (STP) | 0.0899 kg/m³ | Extremely light gas |
| Energy Content | ~120 MJ/kg | Very high |
| Boiling Point | –252.9°C | Cryogenic storage |
| Flammability Range | 4–75% in air | Wide ignition range |
| Storage Pressure | 200–700 bar | Compressed hydrogen |
Typical Impurities (Before Purification)
| Impurity | Source |
|---|---|
| CO | Gasification reactions |
| CO₂ | Shift reaction |
| CH₄ | Incomplete gasification |
| H₂S | Coal sulfur content |
| NH₃ | Nitrogen compounds |
Available Supply Forms
Compressed hydrogen gas (200–700 bar)
Liquefied hydrogen (−253°C)
Pipeline hydrogen supply
On-site gasification-based hydrogen production
Applications
Heavy Industry
Oil refining, steelmaking, cement, glass manufacturing
Chemical Industry
Ammonia, methanol, hydrogenation, synthetic fuels
Power & Energy
IGCC power plants, hydrogen-enriched syngas, co-firing
Metallurgical Processes
Reduction atmospheres, annealing, heat treatment
Safety & Environmental Considerations
Highly flammable gas requiring leak detection, ventilation, and explosion-proof equipment.
Highest lifecycle emissions among hydrogen types; ash, slag, sulfur, and particulate management required.
Hydrogen Comparison
| Parameter | Brown / Black | Grey | Blue | Green |
|---|---|---|---|---|
| Feedstock | Coal / Lignite | Natural gas | Natural gas + CCUS | Water + renewables |
| CO₂ Emissions | Very High | High | Low | Zero |
| Cost | Very Low | Low | Medium | High |
| Scalability | Very High | High | High | Growing |
| Sustainability | Poor | Poor | Moderate | Excellent |
Strategic Role
Short- to medium-term solution for coal-rich economies and heavy industries.
Serves as a transitional pathway when paired with CCUS, gradually phased down in favor of Blue and Green Hydrogen.