Which one of the following is the exhaust pipe emission from Fuel Cell Electric Vehicles, powered by hydrogen?
Contents13
- AHydrogen peroxide
- BHydronium
- COxygen
- DWater vapour
Show answer
Answer: (D) Water vapour
Correct Answer: (d) Water vapour.
In a hydrogen fuel cell vehicle, hydrogen (H₂) reacts with oxygen (O₂) to produce electricity, and the only byproduct is water (H₂O), which exits the exhaust as water vapour and some heat.
This is why hydrogen fuel cells are considered 'zero emission' — no CO₂, no pollutants, just water.
The other options:
- Hydrogen peroxide (H₂O₂) — a reactive chemical, not the normal product.
- Hydronium (H₃O⁺) — an ion found in solutions, not an exhaust gas.
- Oxygen — is consumed as an input, not emitted as output.
Hydrogen fuel cells produce only water vapor as exhaust, making them truly zero-emission vehicles unlike battery EVs which depend on grid electricity sources.
India's National Hydrogen Mission launched in 2021 aims to make India a global hydrogen hub, making hydrogen technology a key current affairs and exam topic.
The question tests understanding of the basic chemical reaction in fuel cells: hydrogen plus oxygen equals electricity plus water.
Hydrogen Fuel Cell Technology
Science And Technology Fuel Cell Electric Vehicles hydrogen
Hydrogen Fuel Cells: Working & Zero Emission Technology
Hydrogen fuel cells produce electricity by combining H₂ + O₂ → H₂O + electricity
Only exhaust emission is water vapour — making it zero emission technology
Fuel cell is an electrochemical device, not combustion engine
Used in Fuel Cell Electric Vehicles (FCEVs) as alternative to battery EVs
Basic Principle
A fuel cell is an electrochemical device that converts hydrogen and oxygen directly into electricity without burning fuel. Unlike internal combustion engines that burn fuel to create mechanical energy, fuel cells produce clean electricity through a chemical reaction.
Fuel Cell Reaction Process
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Hydrogen Input**
**H₂ gas** enters the fuel cell at the anode`"]
s2["`**Oxygen Input**
**O₂ from air** enters at the cathode`"]
s3["`**Electrochemical Reaction**
**2H₂ + O₂ → 2H₂O** produces electrons and ions`"]
s4["`**Electricity Generation**
Electron flow creates **electric current** to power the vehicle`"]
s5["`**Water Emission**
Only byproduct: **water vapour** exits through exhaust`"]
s1 --> s2
s2 --> s3
s3 --> s4
s4 --> s5Question Connection
This UPSC question tests the core advantage of hydrogen fuel cells — zero harmful emissions. The correct answer is water vapour because that's literally the only thing that comes out of the exhaust pipe.
Trap: Hydrogen peroxide (H₂O₂) sounds plausible but is a reactive chemical, not the normal fuel cell product
Trap: Oxygen is consumed as input reactant, not emitted as output
Trap: Hydronium (H₃O⁺) is an ion in solutions, not a gas that exits exhaust pipes
Fuel Cell vs Battery Electric Vehicles
Science And Technology Fuel Cell Electric Vehicles
FCEVs vs BEVs: Two Paths to Electric Mobility
FCEVs use hydrogen fuel cells, BEVs use rechargeable batteries
FCEVs refuel in 3-5 minutes, BEVs charge in 30 minutes to hours
Both produce zero tailpipe emissions during operation
FCEV vs BEV Comparison
Aspect | Fuel Cell Electric Vehicle | Battery Electric Vehicle |
|---|---|---|
Energy Source | Hydrogen gas in tank | Electricity stored in battery |
Refueling/Charging | 3-5 minutes at hydrogen station | 30 min - 8 hours at charging point |
Range | 400-600 km per fill | 200-500 km per charge |
Emissions | Water vapour only | Zero (at point of use) |
Infrastructure | Limited hydrogen stations | Growing charging network |
Cost | Higher vehicle cost | Lower vehicle cost |
Key Advantages Each
FCEVs: Faster refueling, longer range, lighter weight for heavy vehicles
BEVs: Lower cost, established charging infrastructure, higher efficiency
Both: Zero local emissions, quiet operation, reduced oil dependence
Hydrogen as Clean Fuel
Science And Technology hydrogen
Hydrogen: Production Methods & Clean Energy Potential
Green hydrogen produced by renewable energy electrolysis is truly clean
Grey hydrogen from fossil fuels is cheaper but not environmentally clean
Hydrogen can store renewable energy for later use
Hydrogen Production Types
Type | Production Method | Carbon Footprint | Cost |
|---|---|---|---|
Grey Hydrogen | Steam reforming of natural gas | High CO₂ emissions | Lowest cost |
Blue Hydrogen | Grey + carbon capture | Reduced emissions | Medium cost |
Green Hydrogen | Electrolysis using renewable energy | Zero emissions | Highest cost |
Clean Fuel Potential
Hydrogen becomes truly clean fuel only when produced via green methods. While fuel cells always emit just water vapour, the overall environmental impact depends on how the hydrogen was made. Green hydrogen from renewable electricity makes the entire cycle emission-free.
India's National Hydrogen Mission
Science And Technology
India's National Hydrogen Mission: Targets & Strategy
National Hydrogen Mission launched in 2021 to make India a hydrogen hub
Target: 5 MMT green hydrogen production by 2030
Focus on green hydrogen for export and industrial decarbonization
Mission Components
# National Hydrogen Mission
## Production Targets
- 5 MMT green H₂ by 2030
- Renewable energy integration
- Industrial-scale electrolysis
## Applications
- Steel industry
- Refineries
- Fertilizer plants
- Transport fuel
## Economic Goals
- ₹8 lakh crore investment
- Export opportunities
- Job creation
## Infrastructure
- Hydrogen valleys
- R&D centers
- Manufacturing hubsStrategic Importance
Energy security: Reduce dependence on fossil fuel imports
Industrial decarbonization: Clean alternative for steel, cement, chemicals
Export potential: Position India as global green hydrogen supplier