Fuel Cell Electric Vehicles (FCEVs)

Start with the basic idea. A fuel cell turns hydrogen and air into electricity, with water as the only product.

1. What is a Fuel Cell Electric Vehicle?

An FCEV uses an electric motor to turn its wheels. The US Alternative Fuels Data Center (AFDC) says the electricity comes from a fuel cell powered by hydrogen. A battery-electric vehicle draws its electricity only from a battery.

The fuel is pure hydrogen gas kept in a tank on the vehicle. The AFDC says FCEVs fill in about 5 minutes. It also says they have a range of more than 300 miles.

A fuel cell is not quite a battery. The US Department of Energy (DOE) says fuel cells work like batteries, but they do not run down or need recharging. They make electricity and heat as long as fuel is supplied.

• Fuel: hydrogen from a tank.
• Oxygen: taken from the air.
• Output: electricity, water and heat.

2. How does a PEM fuel cell work?

Cars use a type called the polymer electrolyte membrane (PEM) fuel cell. It is also called a proton exchange membrane fuel cell. The AFDC says a thin membrane sits between two electrodes. The negative electrode is the anode. The positive electrode is the cathode.

Hydrogen goes to the anode. Oxygen from the air goes to the cathode. A catalyst at the anode splits each hydrogen molecule into protons and electrons.

The protons pass through the membrane to the cathode. The electrons cannot pass through it. They travel around an external circuit, and that flow is the electric current. At the cathode, the protons, electrons and oxygen join to form water.

• Anode: hydrogen splits into protons and electrons.
• Membrane: lets protons through, blocks electrons.
• Cathode: oxygen, protons and electrons make water.

3. What comes out of the exhaust pipe?

The DOE says that with hydrogen as fuel, the only products are electricity, water and heat. The AFDC says an FCEV emits only water vapor and warm air. So an FCEV has zero harmful tailpipe pollutants.

India’s Press Information Bureau (PIB) says the same. Its 2022 release on the Toyota Mirai says an FCEV has no tailpipe emissions other than water.

Zero tailpipe emission does not mean zero emission everywhere. The AFDC notes that some hydrogen production methods cause air pollution. That depends on how the hydrogen was made.

4. What is inside a fuel cell stack?

One cell makes very little voltage. The DOE says each cell gives less than 1 volt in normal use. So many cells are stacked in a row to get a usable voltage. This assembly is the fuel cell stack.

Each cell has a membrane, catalyst layers and gas layers. The DOE says the membrane in car cells can be under 20 microns thick. Plates between the cells carry gas and electricity.

The usual catalyst is platinum. The DOE says tiny platinum particles are spread on carbon. On the anode side, platinum splits hydrogen. On the cathode side, platinum helps oxygen react to form water.

• Membrane electrode assembly: membrane, catalyst layers, gas layers.
• Bipolar plates: join cells in series and carry the gases.
• Catalyst: platinum on a carbon support.

Exam options often mix up the four vehicle types. Look at the power source and what the battery does.

5. What are the main parts of an FCEV?

The AFDC lists the key parts. This lesson stresses four.

• Hydrogen fuel tank: stores hydrogen gas until the fuel cell needs it.
• Fuel cell stack: joins hydrogen and oxygen to make electricity.
• Battery pack: stores energy from regenerative braking and gives extra power.
• Electric traction motor: drives the wheels using power from the fuel cell and battery.

Other parts help. The power electronics controller manages the flow of electricity. A DC/DC converter changes voltage for accessories. A cooling system keeps the fuel cell and motor at the right temperature.

The AFDC says most FCEVs today use the battery for three jobs. It recaptures braking energy. It gives extra power in short bursts of acceleration. It smooths out the power from the fuel cell. A low-voltage auxiliary battery starts the car and runs accessories.

The size of the hydrogen tank sets how much energy is stored on board. In a battery-electric vehicle, the battery size sets it.

6. How is an FCEV different from a battery-electric vehicle (BEV)?

A BEV has a large traction battery and must be plugged in to charge. The AFDC says it has no fuel tank and no fuel line. An FCEV has a hydrogen tank and a fuel cell. It is filled at a dispenser.

The AFDC says automakers could design an FCEV with plug-in charging. Most FCEVs today do not have it.

The energy supply is also different. In a BEV, power and energy both depend on the battery size. In an FCEV, the motor and fuel cell set the power. The tank sets the energy.

India’s PIB says BEVs may suit light passenger vehicles on short trips. It says FCEVs are likely to become cost competitive for buses, trucks and other heavy vehicles on long trips.

7. How is an FCEV different from a petrol car and a hybrid?

A petrol or diesel car burns fuel in an internal combustion engine (ICE). The AFDC says a gasoline car uses a spark to ignite fuel and air. An FCEV has no combustion. It makes electricity by a chemical reaction.

A hybrid electric vehicle has an engine and one or more electric motors. The AFDC says it cannot be plugged in. Its battery is charged by regenerative braking and by the engine. A hybrid still burns fuel.

An FCEV keeps an electric drive and a battery pack. It makes its electricity in a fuel cell, not in an engine.

The 2025 UPSC paper used the phrase “fuel cell-electric hybrid”. Read such options with care. See item 22.

8. How efficient is a fuel cell vehicle?

Two official claims can be used, and they measure different things. Keep them apart.

The AFDC says a fuel cell with an electric motor is two to three times more efficient than a gasoline car engine. The DOE says fuel cells can convert fuel energy to electricity at efficiencies capable of exceeding 60%.

The DOE figure is about the fuel cell itself. The AFDC figure compares the powertrain with a gasoline engine. Neither source gives a single “FCEV is X% efficient” number.

The AFDC also says hydrogen internal combustion engines are less efficient than FCEVs. They also produce air pollution.

Hydrogen is light, so storing enough of it is the hard part. How it is made decides how clean it really is.

9. How is hydrogen stored on board, and why at high pressure?

The DOE says hydrogen can be stored as a gas or as a liquid. Gas storage typically needs tanks at 350 to 700 bar. That is about 5,000 to 10,000 psi. Liquid storage needs very low temperatures. The boiling point of hydrogen at normal air pressure is minus 252.8 degrees Celsius.

The AFDC names the two common grades. At 5,000 psi, hydrogen is sold as H35. That is 35 megapascals. At 10,000 psi it is sold as H70. The AFDC says light-duty FCEVs sold at dealers have 10,000 psi tanks. Fuel cell buses use 5,000 psi tanks.

High pressure is needed because hydrogen is very light in volume terms. The DOE says hydrogen has nearly three times the energy of gasoline per kilogram. That is 120 MJ/kg against 44 MJ/kg. But liquid hydrogen holds only 8 MJ per litre, against 32 MJ per litre for gasoline.

The AFDC gives a handy comparison. The energy in 1 kg of hydrogen is about the same as in 1 gallon of gasoline.

• Cars: 700 bar (H70), about 10,000 psi.
• Buses: 350 bar (H35), about 5,000 psi.
• Energy per kilogram: hydrogen is about three times gasoline.
• Energy per litre: hydrogen is much lower.

10. What are the colours of hydrogen?

Hydrogen is rarely found alone. The PIB explainer says it must be taken out of other compounds. It sorts hydrogen into three colour groups by the method used.

• Grey hydrogen: made from coal or lignite gasification (black or brown) or from natural gas by steam methane reforming (grey). These are mostly carbon-intensive.
• Blue hydrogen: made from natural gas or coal with carbon capture and storage or use.
• Green hydrogen: made by splitting water with electricity from renewable energy.

The PIB explainer adds a caution about green hydrogen. Its carbon intensity depends on how clean the electricity is.

The DOE says about 95% of all hydrogen is made today by steam reforming of natural gas. India’s Mission document says most Indian hydrogen is also grey. It says about 5 MMT is used each year, mainly in refining and fertiliser. The Mission is built to shift this to green.

India has an official standard for “green”. A 2023 MNRE notification says green hydrogen must have well-to-gate emissions of not more than 2 kg CO2 equivalent per kg of hydrogen. This is a 12-month average. It covers electrolysis and biomass routes.

11. What are the Toyota Mirai and the Hyundai Nexo?

These are two well-known FCEV cars. Both have a fuel cell, a battery and an electric motor.

Toyota introduced the second-generation Mirai in December 2020. Toyota’s US release says the hydrogen is stored in carbon-fibre tanks rated at 10,000 psi. The same release gives an EPA-estimated range of up to 402 miles on the XLE grade.

Toyota’s later release for the 2026 Mirai still gives 402 miles.

Hyundai’s all-new Nexo is a second FCEV example. Hyundai’s November 2025 release gives usable hydrogen of up to 6.69 kg. It gives a projected range of 826 km on the European WLTP test. Hyundai says the refill takes five minutes. Hyundai notes that range can change by market and driving mode.

• Mirai: 10,000 psi tanks, EPA range 402 miles.
• Nexo: up to 6.69 kg of hydrogen, WLTP range 826 km (Europe).
• The DOE says cars need 5 to 13 kg of hydrogen on board across vehicle sizes.

12. Is hydrogen safe in a vehicle?

The DOE says all fuels carry some danger. Safe use means keeping fuel, air and an ignition source from meeting. Hydrogen has some safer traits. It is non-toxic. It is much lighter than air, so a leak spreads out fast.

Hydrogen also needs extra care. The DOE says it has a wide flammable range in air. It needs less energy to ignite than gasoline or natural gas. Its flame is nearly invisible, so special flame detectors are needed. Some metals turn brittle when exposed to hydrogen.

So designers use ventilation, leak detection and the right materials. The DOE says tank leak tests, garage leak simulations and tank drop tests show hydrogen can be produced, stored and dispensed safely.

Toyota describes its own design. Hydrogen sensors detect a leak or a crash. The tank valves are designed to close on their own. India’s Mission document says it will harmonise hydrogen regulations and standards with international norms.

• Good: non-toxic, lighter than air, disperses fast.
• Care needed: easy to ignite, invisible flame, metal embrittlement.
• Controls: ventilation, leak sensors, auto-closing valves, training.

13. How long does refuelling take, and where can you refuel?

The AFDC says retail pumps can fill a car tank in 3 to 5 minutes. Fuel cell buses use 5,000 psi tanks and take 10 to 15 minutes. Toyota’s US release says about five minutes. India’s PIB says the Mirai refuels in under five minutes.

No source checked gives a figure of 2 to 3 minutes. Use about 5 minutes.

Few stations exist. The AFDC says California had 54 public retail hydrogen stations in 2024. They served nearly 15,000 FCEVs.

India’s stations are pilot sites. The IndianOil site at its Faridabad R&D campus dispenses green hydrogen at 350 bar. NTPC’s Leh station has a capacity of 80 kg per day and also fills at 350 bar.

India backs hydrogen through one big mission, a set of pilot schemes and some incentives. Learn the numbers exactly.

14. What is the National Green Hydrogen Mission (NGHM)?

PIB’s release of 4 January 2023 reports that the Union Cabinet approved the Mission. The PIB gives the initial outlay as Rs 19,744 crore. The Ministry of New and Renewable Energy (MNRE) leads it.

The outlay is split into four parts. SIGHT gets Rs 17,490 crore. Pilot projects get Rs 1,466 crore. Research and development gets Rs 400 crore. Other components get Rs 388 crore.

The PIB lists these likely outcomes by 2030.

• Green hydrogen capacity of at least 5 MMT per year.
• About 125 GW of linked renewable energy capacity.
• Over Rs 8 lakh crore in investment.
• Over 6 lakh jobs.
• Over Rs 1 lakh crore saved on fossil fuel imports.
• Nearly 50 MMT of annual emissions avoided.

The MNRE says the Mission aims to make India a global hub for producing, using and exporting green hydrogen. A Cabinet Secretary-led Empowered Group guides it. A Mission Secretariat sits in MNRE.

15. What is SIGHT?

SIGHT stands for Strategic Interventions for Green Hydrogen Transition. The PIB says it has two incentive mechanisms. One supports making electrolysers in India. The other supports producing green hydrogen.

The MNRE page gives the outlay as Rs 17,490 crore up to 2029-30. The same page lists pilot outlays too. Mobility pilots get Rs 496 crore up to 2025-26. Low-carbon steel pilots get Rs 455 crore up to 2029-30. Shipping pilots get Rs 115 crore up to 2025-26.

The Mission also plans at least two Green Hydrogen Hubs in its first phase. It plans a research partnership called SHIP, the Strategic Hydrogen Innovation Partnership.

16. What pilots does the Mission fund for hydrogen vehicles?

MNRE issued guidelines on 14 February 2024. They cover pilot projects for green hydrogen in transport. The scheme supports fuel cell and hydrogen engine buses, trucks and four-wheelers. It also supports hydrogen refuelling stations. The outlay is Rs 496 crore till 2025-26. The Ministry of Road Transport and Highways (MoRTH) helps implement it.

On 3 March 2025 the PIB reported the awards. MNRE sanctioned five pilot projects. They cover 37 vehicles and 9 hydrogen refuelling stations.

• 15 vehicles use fuel cells.
• 22 vehicles use hydrogen internal combustion engines.
• The vehicles will run on 10 routes.
• Government support is about Rs 208 crore.
• Awardees include Tata Motors, Reliance, NTPC, ANERT, Ashok Leyland, HPCL, BPCL and IOCL.

The PIB says the projects should be commissioned in the next 18 to 24 months. On 4 March 2025 Tata Motors began truck trials with 16 hydrogen vehicles. They use hydrogen engines and fuel cells.

17. What are Hydrogen Highways?

The Mission document uses this term. It says certain routes will be marked as Hydrogen Highways, because hydrogen suits heavy-duty and long-haul vehicles. Green hydrogen production, distribution and refuelling stations will be built along them.

The aim is to let hydrogen-fuelled inter-state buses and commercial vehicles run on such routes. The document also says financial help will close the “viability gap” caused by the higher cost of FCEVs in the early years.

The document gives MoRTH a role. MoRTH will enable green hydrogen in transport through rules, standards and codes. It will focus on heavy commercial vehicles and long-haul use. It will also support testing and pilot projects.

The Mission document does not name any specific highway. See item 16 for the 2025 pilot routes.

18. What do PLI, FAME and the vehicle rules say about hydrogen?

The Production Linked Incentive (PLI) scheme for autos was approved on 15 September 2021. It runs for five years from FY 2022-23. It has two parts: a Champion OEM scheme and a Component Champion scheme.

The Champion OEM scheme applies to battery-electric vehicles and hydrogen fuel cell vehicles of all segments. The component scheme gives an extra 5% incentive for parts of battery-electric and hydrogen fuel cell vehicles.

FAME-II is different. The PIB describes FAME-II as a Rs 10,000 crore scheme from 1 April 2019. It backs e-buses, e-three-wheelers, e-four-wheelers and e-two-wheelers, plus charging stations. The PIB page checked does not mention hydrogen.

On rules, the PIB lists three steps.

• 2016: MoRTH notified hydrogen as an automotive fuel for BS VI vehicles.
• September 2020: MoRTH set safety and type approval rules for hydrogen fuel cell vehicles in AIS-157.
• September 2020: an 18% hydrogen blend with CNG (HCNG) was notified as an automotive fuel.

India has tested fuel cell cars and buses in small numbers. Most projects are trials, not products on sale.

19. Which fuel cell car and bus trials began in India?

On 16 March 2022, Union Minister Nitin Gadkari launched the Toyota Mirai in Delhi. The PIB says Toyota Kirloskar Motor and the International Centre for Automotive Technology (ICAT) were running a pilot. The pilot studied the Mirai on Indian roads and in Indian climate.

On 11 December 2025, MNRE launched a new pilot. The National Institute of Solar Energy (NISE) received a Mirai from Toyota Kirloskar Motor. The PIB says NISE will test it for the next 2 years. It will test heat, dust, traffic and varied terrain.

On 21 August 2022, Dr Jitendra Singh launched what the PIB called India’s first truly indigenously developed hydrogen fuel cell bus. It was developed by KPIT and CSIR in Pune. The PIB says its only effluent is water.

In 2021, the PIB reported earlier demonstrations too. They included 6 fuel cell buses by Tata Motors and a fuel cell car by CSIR labs.

20. What are the IndianOil-Tata buses and the NTPC Leh project?

Tata Motors announced on 30 June 2021 that it won a tender for 15 PEM fuel cell buses from Indian Oil Corporation Limited (IOCL). Tata Motors and IOCL would jointly test and operate them in Delhi-NCR. IOCL would make and dispense the hydrogen.

On 25 September 2023, Hardeep Singh Puri flagged off the first two buses at Kartavya Path. The PIB says IndianOil plans 15 buses on routes in Delhi, Haryana and Uttar Pradesh. They are to cover a combined 3 lakh km. The hydrogen is dispensed at 350 bar at the IndianOil R&D campus in Faridabad.

On 23 November 2024, Manohar Lal flagged off NTPC’s green hydrogen buses at Leh. The PIB gives these facts.

• 5 hydrogen intra-city buses.
• A 1.7 MW solar plant on site.
• A filling station with 80 kg per day capacity.
• About 300 km per fill of 25 kg of hydrogen.
• Fills at 350 bar, at 3,650 m above sea level.

The PIB calls it the world’s highest altitude green hydrogen mobility project.

FCEVs are promising but not yet common. Past papers have asked about them in three UPSC prelims.

21. What challenges slow down FCEVs?

The sources point to four problems.

• Cost: India’s Mission document says FCEVs have a higher capital cost in the early years. That is why it offers viability gap support.
• Hydrogen storage: the DOE says dense hydrogen storage remains a significant challenge for transport. Cars need large, high-pressure tanks.
• Few pumps: the AFDC says FCEVs and their fuel infrastructure are in the early stages. California had 54 public stations in 2024.
• Platinum catalyst: the DOE says the common catalyst is platinum on carbon. The sources checked give no platinum cost figure.

Hydrogen production is a fifth issue. The AFDC says electrolysis uses more energy than steam reforming. India’s Mission expects green hydrogen to become competitive with grey hydrogen in the next few years. That is an expectation, not a fact.

The PIB makes one claim in favour of India. It says the fuel cell supply chain can be wholly made in India. It contrasts this with BEV batteries, which need imported lithium and cobalt. Treat that as a government claim.

22. Which UPSC prelims questions touched fuel cells and hydrogen?

The official General Studies Paper I booklets on upsc.gov.in for 2024, 2025 and 2026 were checked. The pages are scans, so the text was read by machine recognition. Question numbers are those printed in the booklet checked. Other booklet series may number them differently. Official UPSC keys (Series A) are used for 2024 Q37, 2024 Q27 and 2025 Q41. For 2026 Q45 the key is provisional.

• CSP 2024, Q37. The options were hydrogen peroxide, hydronium, oxygen and water vapour. Water vapour matches the DOE, the AFDC and the PIB. The official key is (d). The paper reads: “Which one of the following is the exhaust pipe emission from Fuel Cell Electric Vehicles, powered by hydrogen?”
• CSP 2024, Q27: asked how many of four items are “Distributed Energy Resources”. The items were battery storage, biomass generators, fuel cells and rooftop solar units. The official key is (d), all four.
• CSP 2025, Q41: asked how many of three vehicle types are alternative powertrain vehicles. The types were full battery electric, hydrogen fuel cell, and fuel cell-electric hybrid. The official key is (c), all three.
• CSP 2026, Q45: three statements on green hydrogen. Statement 1 describes natural gas reforming with carbon capture. The PIB explainer calls that blue hydrogen. Statement 2 matches the PIB definition of green. Statement 3 matches the PIB 2023 figure of nearly 50 MMT. By the PIB evidence, statements 2 and 3 hold. The provisional key is (b), 2 and 3 only.

23. Which exam claims about FCEVs and hydrogen are wrong?

Watch for these traps.

• “An FCEV emits hydrogen peroxide, hydronium or oxygen.” False. The tailpipe gives water vapour and warm air.
• “An FCEV is just a battery car.” False. The fuel cell makes the electricity that drives the car. A battery supports it.
• “The small battery only helps start the car.” Incomplete. The AFDC says it also takes braking energy and gives extra power in bursts.
• “Zero tailpipe emission means clean hydrogen.” Not always. Grey hydrogen is made from fossil fuels. The tailpipe is clean, but the fuel may not be.
• “Green hydrogen is made from natural gas with carbon capture.” False. That is blue. Green comes from water electrolysis with renewable power.
• “Hydrogen has less energy than petrol.” Half true. Per kilogram it has about three times more. Per litre it has far less.
• “5 MMT is India’s green hydrogen today.” False. About 5 MMT is the grey hydrogen India uses each year. The Mission target for green hydrogen by 2030 is at least 5 MMT per year.
• “The Mission outlay is Rs 17,490 crore.” That is only SIGHT. The total is Rs 19,744 crore.
• “FAME-II gives money for hydrogen cars.” Not supported by the PIB page checked. The PLI auto scheme does cover hydrogen fuel cell vehicles.