A fuel cell electric vehicle (FCEV), like a BEV, only has an electric motor, but it uses a different method to store and extract electricity. In FCEVs, much of the traction battery is replaced by a hydrogen tank and a set of fuel cells in which a chemical reaction transforms hydrogen into electricity and water vapour. This may sound like a highly promising solution, but when we take into account the design complexity and production costs, hydrogen remains a long way off.
Hybrid electric vehicles (HEVs) can be broken down further into sub-forms. In principle, there are two ways of doing this. In the first method, they are classified according to the drivetrain set-up, as series, parallel and power-split hybrids.
A SERIES hybrid
is always powered purely by the electric motor. The internal combustion engine is there only to recharge the batteries. This hybrid comes to the fore in urban traffic and, above all, in stop-and-go driving, where conventional cars’ internal combustion engines are less efficient.
A PARALLEL hybrid
can be powered either by the internal combustion engine alone, by the electric motor alone, or by both combined. It is more efficient than a series hybrid at higher speeds, when it can draw on the potential offered by the two-motor combo if the need arises.
A power-split hybrid
can switch between the series and parallel modes to harness the advantages of each. This means that it can be powered by an electric motor only, by an internal combustion engine only, or by a combination of the two.