In this blog, understand what is hydrogen engine, what are its types, hydrogen engine working and more..
Table of Contents
What is a Hydrogen engine?
A hydrogen engine is a type of engine that uses hydrogen gas as a fuel source to produce mechanical power, either through combustion or electrochemical reaction, with minimal or zero harmful emissions.
Hydrogen Engine types?
There are two main types of hydrogen engines, each with distinct characteristics:
- Hydrogen Internal Combustion Engine (H2-ICE):
- Burns hydrogen in a modified internal combustion engine.
- Hydrogen Fuel Cell Engine (FCEV):
- Uses a fuel cell to convert hydrogen into electricity, which then powers an electric motor.
What is the difference between hydrogen internal combustion engine and hydrogen fuel cell
| Feature | Hydrogen ICE | Hydrogen Fuel Cell (FCEV) |
|---|
| Working Principle | Burns hydrogen in an engine | Converts hydrogen to electricity in a fuel cell |
| Output | Mechanical power | Electrical power (then to motor) |
| Efficiency | Lower (about 25–30%) | Higher (around 50–60%) |
| Emissions | Mostly water, minor NOx | Pure water vapor only |
| Noise Level | Similar to petrol/diesel engines | Very quiet (like electric vehicles) |
| Technology Maturity | Easier to adapt from existing engines | More advanced, but needs more R&D |
| Maintenance | Similar to conventional engines | Fewer moving parts, lower maintenance |
| Vehicle Examples | Modified Toyota Corolla (prototype) | Toyota Mirai, Hyundai Nexo |
| Refueling Time | 3–5 minutes | 3–5 minutes |
| Driving Experience | Like a traditional car | Smooth and quiet like EV |
How does Hydrogen internal combustion engine works?
1. Hydrogen Fuel Intake
- Hydrogen (H₂) gas is stored in a high-pressure tank.
- Enters the engine through fuel injectors.
- Air (O₂) from the atmosphere is also drawn in.
➡️ Reactants:2H₂ (gas) + O₂ (gas) (from air)
2. Compression Stroke
- Piston moves up.
- Compresses Hydrogen + Air mixture inside the cylinder.
🛠️ No chemical reaction yet – just mechanical compression.
3. Ignition / Combustion Stroke
- A spark plug ignites the compressed hydrogen-air mix.
- Hydrogen burns rapidly, releasing energy and high-pressure gas.
Combustion Reaction as follows : 2H₂ + O₂ → 2H₂O + heat
➡️ Products:
- Water vapor (H₂O)
- Large amount of heat energy
4. Power Stroke
- The expanding hot gases push the piston down.
- Converts chemical energy into mechanical energy.
- This drives the crankshaft, which powers the vehicle.
➡️ No new reaction – mechanical conversion of heat to motion.
5. Exhaust Stroke
- The piston moves up again, pushing out exhaust gases through the exhaust valve.
➡️ Exhaust Products:
- Water vapor (H₂O)
- Small amount of Nitrogen Oxides (NOx) (if combustion temperature is high)
⚠️ NOx formation (undesired side reaction):
N₂ + O₂ → 2NO (at high temperatures)
How does Hydrogen Fuel Cell Engine Works?
1. Hydrogen is stored
Hydrogen gas (H₂) is kept in high-pressure tanks in the vehicle.
2. Air is taken in
The system pulls in air from the environment. This provides oxygen (O₂) for the chemical reaction.
3. Fuel cell reaction starts
Hydrogen enters the anode side of the fuel cell. Here, each hydrogen molecule splits into:
- Protons (H⁺) – pass through a membrane.
- Electrons (e⁻) – flow through a wire (creating electricity).
4. Electricity powers the motor
The flow of electrons powers the electric motor, which moves the vehicle.
5. Reaction at the cathode
On the other side (cathode), protons, electrons, and oxygen combine to form water (H₂O).
6. Clean exhaust
The only emission from the tailpipe is water vapor – no pollution.
