Q. Consider the following types of vehicles:

1. Full battery electric vehicles
2. Hydrogen fuel cell vehicles
3. Fuel cell-electric hybrid vehicles

How many of the above are considered as alternative powertrain vehicles? (UPSC Prelims 2025)
Answer: All the three
Notes: The correct answer is [C] All the three. An "alternative powertrain" refers to any vehicle propulsion system that differs from the traditional Internal Combustion Engine (ICE) powered solely by gasoline or diesel.

• Full Battery Electric Vehicles (BEVs): These vehicles use an electric motor powered by a large onboard battery pack charged from the grid. Since they lack an internal combustion engine and rely entirely on electricity, they are a primary category of alternative powertrains.
• Hydrogen Fuel Cell Vehicles (FCEVs): These vehicles use a fuel cell stack that converts compressed hydrogen gas into electricity through a chemical reaction with oxygen. Because they use a fuel cell instead of a traditional engine, they are classified as alternative powertrain vehicles.
• Fuel Cell-Electric Hybrid Vehicles: These vehicles combine a hydrogen fuel cell with a rechargeable battery to provide power to the electric motor. This hybrid configuration optimizes efficiency and performance, and since it utilizes a fuel cell as its primary or secondary energy source, it falls under the alternative powertrain umbrella.

Key Technical Context: Alternative powertrains are designed to reduce dependence on fossil fuels and lower greenhouse gas emissions. While BEVs are currently the most common in the passenger segment, FCEVs are gaining traction for long-haul heavy-duty transport due to faster refueling times and higher energy density compared to current battery technology.