Why Hydrogen Cannot Be Used as a Practical Fuel: A Thermodynamic
Explanation
(CEWT – Carbon Recycling Technology Insight Series)
1. Introduction
Hydrogen is frequently promoted as a “clean fuel,” yet the laws of thermodynamics show that
hydrogen can never function as a practical primary fuel source. Hydrogen is not an energy
source at all — it is only an energy carrier, and a very inefficient one.
CEWT’s Carbon Recycling Technology (CRT) is built firmly on thermodynamic reality.
This article explains, with scientific clarity, why hydrogen cannot be used as a fuel and why
renewable methane (RNG) from CRT is the correct pathway for energy storage and baseload
power.
2. Thermodynamic Foundations
2.1 Water Splitting: An Endothermic Reaction
Electrolysis breaks water into hydrogen and oxygen:
H2O (l) => H2 (g) + 1/2O2 (g)
This reaction requires external energy because of water’s stable molecular structure.
• ΔH (liquid water) = +285.83 kJ/mol
• ΔH (water vapour) = +241.83 kJ/mol
This is strongly endothermic.
It consumes energy — you must put energy in to obtain hydrogen
2.2 Hydrogen Combustion or Fuel-Cell Reaction: Exothermic
When hydrogen is used (in a turbine or fuel cell), it recombines with oxygen:
H2 (g) + 1/2}O2 (g) +> H2O
This releases heat:
• ΔH = –285.83 kJ/mol (forming liquid water)
• ΔH = –241.83 kJ/mol (forming vapour)
This is exothermic.
However — and this is the critical point — the amount of energy released is always exactly
equal to the amount of energy originally used to split the water, if ideal and reversible.
Thus:
Hydrogen offers no net energy gain. It only returns what was already invested.
And this is the best-case scenario. In practice, the losses are severe.
3. Real-World Thermodynamics: Where Hydrogen Fails
Even if electrolysis and fuel cells were 100% efficient (they are not), hydrogen would still not
be a fuel — it is simply a temporary storage medium.
But in real systems:
Electrolyser efficiencies:
65–75%
Fuel cell efficiencies:
40–60%
Compression/liquefaction losses:
10–35%
Transport & storage losses:
5–10%
Putting this together:
Overall efficiency = approx 20–25%
This means 75–80% of renewable electricity is permanently lost when routed through
hydrogen.
This is thermodynamically unavoidable.
4. Why Hydrogen Cannot Be a Fuel — Thermodynamic
Interpretation
4.1 Fuel Definition (Thermodynamic)
A true fuel must provide net positive available work (Gibbs free energy).
But for hydrogen:
G electrolysis = -G fuelcell
• Electrolysis demands free energy
• Fuel cells return the same free energy
• Net → zero, minus losses
Thus hydrogen does not satisfy the definition of a fuel.
4.2 Exergy Losses
Hydrogen suffers extremely high exergy destruction because:
• Storage (especially compression) increases entropy
• Leakage increases entropy
• Transport and boil-off add irreversible losses
• Fuel cells produce water vapour → latent heat losses
Thermodynamically:
s (total )> 0
Irreversibility is large → system cannot approach ideal efficiency.
Thus, hydrogen becomes a severely degraded energy carrier.
4.3 Chemical Potential Argument
The chemical potential of hydrogen as a fuel is fundamentally tied to the stability of water:
• Water is one of the lowest free-energy states in nature
• Hydrogen is one of the highest
Therefore:
Hydrogen cannot be a “fuel” while water is the thermodynamic sink.
Hydrogen must always be forced uphill using external energy.
5. CRT’s Solution: Using Hydrogen Properly
Hydrogen is valuable — but not as a fuel.
Its correct use is:
Renewable H2 + Captured CO2 => Renewable Methane (Renewable Synthetic Methane Gas)
Methane (CH4) has:
• Higher chemical exergy
• Lower storage entropy
• 3–6× better volumetric energy density
• Stable molecular structure
• 100-year established infrastructure
• Perfect compatibility with gas turbines
• Much lower lifecycle energy losses
In short:
Hydrogen should never be burned.
It should be converted into renewable methane.
This is what CEWT’s Carbon Recycling Technology achieves.
6. Conclusion
Hydrogen cannot be used as a practical fuel because thermodynamics forbids it:
• Electrolysis is endothermic
• Fuel cells are exothermic but return less than what was invested
• Inefficiencies are irreversible
• Net energy chain loses 75–80%
• Hydrogen provides no net usable energy
• It fails the thermodynamic definition of a fuel
Renewable methane (RNG) created from renewable hydrogen + captured CO2 in CEWT’s
Carbon Recycling Technology solves this fundamental limitation.
It delivers a true fuel, with high exergy, stable storage, and zero net emissions.
