Analysis of Hydrogen Leakage's Climate Impact: Mechanisms, Sources, Leakage Rates, and Greenhouse Equivalence
July 26, 2026
VAHC R&D
I. Climate Impact Mechanisms of Hydrogen Leakage
Hydrogen itself is not a greenhouse gas, but when leaked into the atmosphere, it causes global warming through indirect mechanisms. Hydrogen molecules react with hydroxyl radicals in the atmosphere. Hydroxyl radicals act as the primary "cleanser" of the atmosphere, responsible for breaking down methane and other greenhouse gases. However, because the daily production of hydroxyl radicals is limited, large-scale hydrogen leakage consumes a significant portion of them, reducing the atmosphere's capacity to break down methane, thereby extending methane's atmospheric lifetime and intensifying the greenhouse effect. Additionally, hydrogen leakage also affects ozone and stratospheric water vapour concentrations, which are also important greenhouse agents.
II. Sources of Hydrogen Leakage
Hydrogen leakage occurs across the entire supply chain, including:
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Production: During water electrolysis, venting and purging operations during operation and maintenance.
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Transport and storage: Leakage from pipelines (especially hydrogen-blended natural gas pipelines), truck transport, and boil-off losses during liquid hydrogen storage.
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End-use: Leakage from fuel cell vehicles, refuelling stations, and hydrogen combustion systems in gas turbine power plants.
Additionally, hydrogen can also be generated and leaked from landfills, wastewater, and natural geological sources.
III. Global Hydrogen Production 2025: Exceeding 100 Million Tonnes
According to the IEA Global Hydrogen Review 2026, global hydrogen demand in 2025 exceeded 100 million tonnes. In 2024, global hydrogen demand reached approximately 97 million tonnes, with 2025 growth of approximately 3%.
Among this, low-emission hydrogen (including green hydrogen and blue hydrogen) production in 2025 reached approximately 1 million tonnes, accounting for less than 1% of total production.
| Indicator | 2024 | 2025 |
|---|---|---|
| Global hydrogen demand | ~97 Mt | >100 Mt |
| Low-emission hydrogen production | ~0.8 Mt | ~1.0 Mt |
| Low-emission hydrogen share | <1% | <1% |
IV. Hydrogen Leakage from Landfills and Natural Sources
1. Landfills and Waste
Waste decomposing in landfills generates methane, which can be reformed into hydrogen. A global 2025 study modelling 9,096 landfills worldwide found the potential hydrogen production from these landfills to be approximately 300,000 tonnes of hydrogen per year.
Note: This is production potential, not actual leakage.
2. Natural Geologic Hydrogen Sources
Hydrogen is naturally generated from geological reactions and seeps to the surface. The largest natural seepage point ever recorded is at Nagsasa, Zambales, Philippines, with emissions of approximately 808 tonnes of hydrogen per year.
Currently, approximately 60 natural hydrogen seepage points have been identified globally.
V. Hydrogen Leakage Rates Across the Supply Chain
According to a 2025 US hydrogen emissions study, the average leakage rate across the entire US hydrogen supply chain is 0.79% (range 0.26% to 1.32%).
However, leakage rates vary significantly by segment:
| Segment | Leakage Rate |
|---|---|
| Grey/blue hydrogen production | 0.1% – 1% |
| Green hydrogen production (electrolysis) | 2% – 4% |
| Hydrogen liquefaction | 10% – 20% |
| Pipeline transport, underground storage, refuelling stations | Varies by infrastructure |
Notably: Green hydrogen has significantly higher production-stage leakage rates than grey hydrogen.
VI. Greenhouse Equivalence of Hydrogen Leakage
Global Warming Potential of hydrogen:
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GWP₂₀ (20-year timescale): 37 ± 18
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GWP₁₀₀ (100-year timescale): 11 ± 4
If global hydrogen production in 2025 reaches 100 million tonnes, applying the average leakage rate of 0.79%:
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Annual leaked hydrogen: 790,000 tonnes
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CO₂-equivalent (GWP₂₀ = 37): approximately 29 million tonnes CO₂/year
If the leakage rate reaches 1%:
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Annual leaked hydrogen: 1 million tonnes/year
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CO₂-equivalent (GWP₂₀ = 37): 37 million tonnes CO₂/year
VII. Data Summary
| Indicator | Value |
|---|---|
| Global hydrogen production 2025 | >100 Mt |
| Low-emission hydrogen production 2025 | ~1 Mt (<1%) |
| US supply chain average leakage rate | 0.79% |
| Green hydrogen production leakage rate | 2% – 4% |
| Hydrogen liquefaction leakage rate | 10% – 20% |
| Global landfill hydrogen production potential | ~300,000 tonnes/year |
| Largest natural seepage point (Philippines) | ~808 tonnes/year |
| CO₂-equivalent at 1% leakage (GWP₂₀) | ~37 Mt CO₂/year |
VIII. Conclusion
Hydrogen leakage is not just a technical issue but also a climate issue. With global production exceeding 100 million tonnes per year, even a small leakage rate can create significant greenhouse impacts. Strict monitoring and leakage control standards are essential as the hydrogen industry scales up.
Forecast of Hydrogen Leakage in 2050 and Its Greenhouse Gas Impact
Based on current scientific research, below is a forecast of hydrogen leakage by 2050 and its impact on the global greenhouse effect.
1. Global Hydrogen Production in 2050
According to various scenarios, global hydrogen demand in 2050 varies widely:
| Scenario | Hydrogen Demand 2050 (Mt/year) | Source |
|---|---|---|
| Average across studies | ~590 | [6†L7-L8] |
| Net Zero Scenario (IEA NZE) | ~420 – 528 | [10†L8][2†L32-L33] |
| Ambitious Scenario (100% final energy) | Up to 3,000 | [6†L15-L16] |
Forecasts indicate that hydrogen demand in 2050 will increase 5-10 times compared to the ~100 million tonnes in 2024, with an average of approximately 590 million tonnes per year.
2. Hydrogen Leakage Rates in 2050
By 2050, hydrogen leakage rates across the supply chain could vary significantly, depending on technological development and control measures:
| Scenario | Projected Leakage Rate 2050 | Source |
|---|---|---|
| Optimistic | <2% | [7†L25-L26][9†L32-L33] |
| Average | ~5% | [0†L5] |
| Worst-case | up to 20% | [7†L26-L27][9†L32-L33] |
Important note: Green hydrogen (produced via electrolysis) has significantly higher production-stage leakage rates compared to grey hydrogen (2-4% vs. 0.1-1%), due to venting and purging operations during electrolyser operation and maintenance. Additionally, liquid hydrogen is expected to become a major leakage source due to boil-off losses during transport and refuelling.
3. Leaked Hydrogen Volume and CO₂-Equivalent Conversion
Applying different scenarios to ~590 Mt/year hydrogen production (average level):
| Scenario | Leakage Rate | Leaked Hydrogen (Mt/year) | CO₂-equivalent* (Mt/year) |
|---|---|---|---|
| Optimistic | 2% | 11.8 | ~137 |
| Average | 5% | 29.5 | ~342 |
| Worst-case | 10% | 59.0 | ~684 |
| Extreme | 20% | 118.0 | ~1,369 |
*Calculated using GWP100 = 11.6 (1 kg H₂ ≈ 11.6 kg CO₂)
According to IEA calculations for the Net Zero scenario (420 Mt/year, ~2% leakage), leaked hydrogen is equivalent to approximately 100 million tonnes CO₂/year.
Another study projects hydrogen leakage into the atmosphere in 2050 under a high-demand scenario at 12.2 million tonnes.
4. Contribution to Global Greenhouse Effect
With current total global greenhouse gas emissions at approximately 60.63 billion tonnes CO₂-equivalent/year, the contribution of hydrogen leakage:
| Scenario | CO₂-equivalent (Mt/year) | Share of Global Emissions |
|---|---|---|
| Optimistic (2% leakage) | ~137 | ~0.23% |
| Average (5% leakage) | ~342 | ~0.56% |
| Worst-case (10% leakage) | ~684 | ~1.13% |
| Extreme (20% leakage) | ~1,369 | ~2.26% |
This share could increase significantly if hydrogen production reaches 3,000 Mt/year (100% final energy scenario).
5. Global Temperature Impact
Beyond percentage contributions, hydrogen leakage also causes global surface temperature increases:
| Hydrogen Demand Scenario 2050 | Temperature Increase (1% leakage) | Temperature Increase (10% leakage) |
|---|---|---|
| 20% final energy (~590 Mt) | 0.005 ± 0.001°C | 0.05 ± 0.01°C |
| 50% final energy | 0.01 ± 0.02°C | 0.12 ± 0.03°C |
| 100% final energy (theoretical) | 0.02 ± 0.04°C | 0.27 ± 0.05°C |
If hydrogen is used for 100% of final energy demand in 2050, with a 5% leakage rate, warming could exceed >0.1°C, and with 10% leakage, it could reach up to 0.4°C.
6. Summary of 2050 Projections
| Metric | Projected 2050 Value |
|---|---|
| Global hydrogen production | 420 – 590 Mt/year (up to 3,000 possible) |
| Leakage rate | 2% (optimistic) – 20% (worst-case) |
| CO₂-equivalent | 100 – 1,369 Mt/year |
| Share of global emissions | 0.2% – 2.3% |
| Temperature increase (average scenario) | ~0.05°C – 0.12°C |
In the average scenario (production ~590 Mt/year, leakage ~5%), hydrogen leakage could contribute approximately 0.5-0.6% of total global greenhouse gas emissions, equivalent to approximately 0.05-0.1°C of temperature increase.
Although this share remains small compared to CO₂ emissions from fossil fuels, it demonstrates that hydrogen leakage will become a climate issue that cannot be ignored if the hydrogen industry scales up without stringent leakage control standards.
