The current 80 km range of hybrid electric vehicles’ fuel cells could treble in the next decade as the power and energy density of modern fuel cells and batteries improve and supercapacitors enable electric motors to manage load changes on vehicle motors, says market research company IDTechEx chairperson Dr Peter Harrop.
The hybrid vehicle is evolving to become more like a pure electric vehicle. The battery is doing more of the work and the conventional engine is doing less of the work, which increasingly involves not providing direct wheel drive but only the function of charging the battery during travel, he says.
However, the hybrid vehicle will not end up with the batteries capable of holding hundreds of kilowatt hours similar to larger pure electric vehicles because batteries are still the Achilles heel of electric vehicles, limiting price reduction, performance and life.
“We shall, therefore, see fast charging of the vehicle – frequent top-up – becoming feasible, reducing the size of the battery required even as all-electric ranges of hybrid vehicles increase in response to demand from users. Hybrid vehicles can save a significant amount of money by using electricity whenever possible and, therefore, be greener,” says Harrop.
An increasing variety of energy harvesting and use of supercapacitors in vehicles will also reduce the size of the traction batteries required. This means that traction batteries in hybrid vehicles will become bigger but will not become as large as those used in pure electric vehicles. Hybrid vehicles increasingly emulate pure electric vehicles by having a high-energy density to provide a longer-functioning all-electric range.
Better batteries, notably nickel-metal hydride and lithium-ion, are able to take over more of the work of traction from the engine and it has been feasible to trial smaller fuel cells aimed at achieving an affordable fuel cell range extender for hybrid vehicles.
Range extenders, owing to the improved batteries, now work at fairly constant torque and revolutions, similar to a piston or turbine motor, or with fairly constant power output if they generate electricity directly, as is the case with a fuel-cell range extender.
Further, fuel cells and lithium-ion traction batteries will increasingly be seen working together in driving land, sea and air vehicles. Their relationship is changing but they have much in common. For example, third-generation lithium-ion batteries are often solid state, employing circuit printing technology and allied nanotechnology, capabilities also brought to bear in the newer fuel cells, he concludes.