Decision making Which type of electric vehicle should I choose?
The term ‘Electric Vehicle’ covers many vehicle types, which differ in how they deploy petrol and electrical energy. This article looks at the major options currently available, and their relative merits for motorists.
Uptake of electric vehicles has so far been relatively limited, due to high capital costs and concerns about sufficient availability of charging points. However, this is likely to change with growing pressure and legislation for reduced or zero emissions, and an increasing choice of more affordable vehicles.
A closer look at this growing choice soon reveals that the term ‘electric vehicle’, or EV, is an umbrella term for many types, some of which use petrol engines as well as electric motors. The optimum configuration for any user depends on the type of driving conditions they regularly face. Accordingly, the review of the options available below provides a starting-point for your own research into your ideal solution.
Battery Electric Vehicles
A Battery Electric Vehicle (BEV) – also known as a ‘pure’ electric vehicle - uses only electrical power, in the form of one or more electric motors and battery-based energy storage. The Jaguar I-pace, for example, has two electric motors and a four-wheel drive, while the Nissan Leaf is front-wheel drive with one electric motor.
With no petrol engine, BEVs are pollution-free in use, but their range is limited by their batteries’ storage capacity. However, the batteries can be charged both by plugging them into a recharging point, and by using regenerative braking. Regenerative braking systems put the vehicle’s motor into reverse mode when the driver steps on the brake pedal. The motor becomes a generator, which uses the vehicle’s kinetic energy to recharge the batteries rather than letting it go to waste as heat in the brake pads.
Plug-in charging can be performed from domestic power outlets as well as dedicated charging points in service stations. However, a home charging point is recommended, as it offers significantly better charging efficiency.
BEVs are best for short to medium commutes, such as school runs, shopping trips or possibly day outings.
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Hybrid electric vehicles – mild and plug-in types
Unlike BEVs, hybrid electric vehicles (HEVs) use both petrol engines and electric motors working in tandem. HEVs can be of either mild hybrid or plug-in hybrid type.
Mild hybrid electric vehicles (MHEVs) have an electric motor that assists the petrol engine. The motor, which operates at 48 volts, cannot alone propel the vehicle. It kicks in during startup or other times of heavy fuel demand, and can also boost the engine’s performance during acceleration. The vehicle’s battery is only charged by regenerative braking, with no plug-in charging.
MHEVs’ main advantage is lower fuel consumption, but since their exhaust emissions are reduced rather than eliminated, they rank well below BEVs for sustainability. However, they are attractive to motorists seeking to make longer journeys without the worry of in-journey battery recharging.
Unlike MHEVs, plug-in hybrid electric vehicles (PHEVs) can recharge their batteries through plug-in charging as well as regenerative braking. This allows more powerful electric motors, and enables PHEVs to be driven distances of 30 miles or more on electric power only. This means that they can have a ‘zero emission range’. Many motorists’ daily commutes are below 30 miles, so they will be able to complete them using only environmentally-friendly electricity, with lower fuel costs.
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The BMW 530e iPerformance, for example, can cover 28 miles on electricity only, starting with a fully-charged battery. Over the next few years, technological advances will significantly improve the range of electric motors – as well as that of all battery-powered cars.
However, the PHEV’s petrol engine also allows much longer trips, using filling stations just like conventional vehicles. PHEVs are therefore attractive for motorists who want the flexibility of a vehicle that fulfils all their local and longer-distance travel needs, with both electric motor benefits and petrol engine range and flexibility.
Hydrogen fuel cell electric vehicles
Hydrogen fuel cell electric vehicles (FCEVs) are advanced EVs that are powered by an electrochemical process which combines hydrogen and oxygen. This process happens in an intelligent fuel stack which fuses highly pressured hydrogen gas with oxygen, thereby creating a reaction that produces the electricity required to power the vehicle’s motor and drive its wheels. This process means the only exhaust it produces is water.
Because hydrogen fuel cell cars are powered by the chemical process of fusing hydrogen and oxygen, they do not need to be recharged and can be driven as long as they are fuelled by a supply of hydrogen. Filling up the car takes less than 5 minutes and the average range of hydrogen fuel cell cars is around 300-350 miles. They can be used similarly to conventional petrol powered vehicles, for shorter commutes as well as much longer journeys.
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One problem, however, is that filling stations are few and far between and little progress is being made in adding new ones. Should this change in the future then there would be little difference between operating a FCEV and a petrol engine car.
It is also still very expensive to manufacture fuel cell systems. One of the main reasons for this is that platinum is needed for the catalytic converter.
Motorists can already choose from a range of electric vehicle configurations to find the solution that best suits their lifestyle. This choice is set to grow as manufacturers develop more models to meet the social and legislative pressures to ‘go green’.