Production Efficiency
- Energy input:
Green hydrogen production via electrolysis typically requires 20–30% more energy input per unit of energy output compared to direct renewable electricity use (due to electrolysis efficiency losses ~70–80%).- Example: Generating 1 kg of hydrogen (33.3 kWh energy content) requires ~50 kWh of renewable electricity.
- Comparison: Renewables like solar/wind directly supply electricity at ~90–95% efficiency post-generation (excluding storage losses), making them inherently more efficient than hydrogen production.
End-Use Efficiency
- Transportation:
- Fuel cells convert hydrogen to electricity at 40–60% efficiency, competing with battery-electric vehicles (70–90% efficiency from grid to wheels).
- Hydrogen’s high energy density per mass (~33.3 kWh/kg) benefits aviation and heavy transport, where batteries are weight-limited.
- Heating:
- Heat pumps deliver 300–400% efficiency (1 kWh electricity → 3–4 kWh heat), vastly outperforming hydrogen boilers (1 kWh hydrogen → ≤1 kWh heat).
- Green hydrogen heating achieves lower emissions than gas boilers only after 2026, while heat pumps already reduce emissions by 73% today.
- Industrial Processes:
Hydrogen is critical for hard-to-electrify sectors (e.g., steelmaking), where alternatives like electrification face technical hurdles.
Environmental Impact
- Green vs. Blue Hydrogen:
- Green hydrogen emits 0 kgCO₂/kg H₂, while blue hydrogen emits 3.5–4 kgCO₂/kg H₂ (even with carbon capture).
- Blue hydrogen’s methane leaks and reliance on fossil fuels undermine net-zero goals.
- Water Use:
Green hydrogen requires 10 liters/kg H₂ via electrolysis, half that of blue/grey hydrogen (23–25 liters/kg H₂).
Key Trade-offs
| Aspect | Green Hydrogen | Direct Renewables | Heat Pumps |
|---|---|---|---|
| Efficiency | Medium (~40–60%) | High (≥90%) | Very High (300–400%) |
| Scalability | Requires massive renewables | Mature but grid-dependent | Limited to electrified sectors |
| Cost | High ($3–6/kg) | Low ($0.03–0.10/kWh) | Moderate (upfront costs) |
Conclusion
Green hydrogen is less efficient than direct renewable electricity or heat pumps but remains pivotal for sectors requiring high-density energy or high-temperature heat. Its viability hinges on reducing electrolysis costs and scaling renewable energy.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-green-hydrogen-compare-to-other-clean-energy-sources-in-terms-of-efficiency-2/
