Science & Tech · Fuel Cells (Hydrogen, PEM)
The concept being tested: Alternative powertrain vehicles — classification and types.
Consider the following types of vehicles: I. Full battery electric vehicles II. Hydrogen fuel cell vehicles III. Fuel cell-electric hybrid vehicles How many of the above are considered as alternative powertrain vehicles?
Alternative powertrain vehicles are those that replace the conventional petrol or diesel internal combustion engine with an electric drive, regardless of how that electricity is generated or stored. Full battery electric vehicles store electricity directly in an onboard battery pack and feed it to an electric motor. Hydrogen fuel cell vehicles carry compressed hydrogen and pass it through a fuel cell stack, where it reacts electrochemically with oxygen to generate electricity on demand, releasing only water as waste. Fuel cell-electric hybrid vehicles combine both routes, pairing a fuel cell with a buffer battery that captures regenerative braking energy and smooths power delivery to the motor. In each of these three configurations the wheels are turned by an electric motor, not a combustion engine, so all three qualify as alternative powertrain vehicles, which is why all the three types listed are the correct count.
What UPSC was testing
The trap here is the word hybrid in fuel cell-electric hybrid vehicles, which tempts aspirants to assume it means a petrol-electric hybrid that still carries a combustion engine. UPSC is testing whether the aspirant knows that this hybrid pairs two electric sources, a fuel cell and a battery, with no internal combustion engine involved.
How often this comes up
This concept has appeared 8 times in UPSC Prelims General Studies Paper I between 2015 and 2025 — in 2016, 2019, 2023, 2024 and 2025.
The option-by-option autopsy for this question — why each of the other three is wrong, and which neighbouring concept each one was built from — is in the app.
Other past-year questions touching Fuel Cells (Hydrogen, PEM).