Recent Trends, Alternative Fuels and Electric Vehicles
Recent Trends, Alternative Fuels and Electric Vehicles
This domain covers emerging vehicle technologies and their basic principles. The exam tests alternative fuels such as ethanol, biodiesel, CNG and hydrogen, hybrid layouts, EV components, battery types, regenerative braking and charging.
Core rules
- Ethanol blending reduces fossil petrol use; E10 contains 10% ethanol by volume. Biodiesel is derived from vegetable oils or animal fats and is used in CI engines.
- CNG is stored as a high-pressure gas and burned in SI engines; hydrogen can power fuel cells or spark-ignition engines.
- Hybrids combine an engine and electric motor. In a series hybrid the engine drives a generator; in a parallel hybrid both can drive the wheels.
- Battery electric vehicles use a traction battery, inverter, motor and reduction gear. Regenerative braking recovers some kinetic energy; it does not recover all of it.
Worked example
An EV has a 30 kWh usable battery and a tested range of 200 km. Average consumption = 30 kWh ÷ 200 km = 0.15 kWh/km, or 150 Wh/km. At a 7 kW charger, an ideal 0–100% charge takes 30 ÷ 7 ≈ 4.3 hours, excluding losses and tapering. Reasoning: kWh is energy, kW is power; time = energy ÷ power.
Traps
- Confusing kW (power) with kWh (energy).
- Assuming regenerative braking charges the battery fully or works at very low speed.
- Saying a series hybrid's engine drives the wheels mechanically; it drives a generator.
- Treating E10 as 10% petrol rather than 10% ethanol.