Almost all of the cars New Zealanders drive today are “conventional” vehicles, which use internal combustion engines and run only on liquid or gaseous fuels – mainly petrol or diesel, although a tiny number use other fuels such as compressed natural gas or biofuels. In the future – and I’m talking fairly long-term, at least a couple of decades out – we’re likely to see “advanced” and electric vehicles playing a larger role. These vehicles are pretty expensive, and it’s still very early days for the technology, but they could potentially reduce dependence on oil, and – although this is trickier – reduce greenhouse gas emissions.
In this post I’ll just give a quick overview of the technology – I’ll leave discussion of the pros and cons for another day.
Hybrid cars use two different methods of providing forward motion: an engine, and an electric motor. The engine generates energy, which charges the battery – same as a regular car up to this point – and the battery is then used to run the motor.
There are a number of “hybrid” cars on the road today, and they are some of the most efficient cars currently available. Generally, these hybrids run entirely on petrol or diesel. As such, they can be simply thought of as particularly efficient conventional vehicles, rather than advanced ones.
Hybrids can improve fuel efficiency by more than 40%, compared to similarly sized, non-hybridised cars. That’s a fairly substantial saving. However, hybrid cars cost more to build: the International Energy Agency estimates that, even without considering development costs, hybrids currently cost around USD $2,450 more to build than comparable petrol cars.
The Toyota Prius is the world’s top-selling hybrid, and probably the most famous. There are plenty of these in New Zealand, many of them being driven as taxis (they seem to be the main car in the Co-Op Taxis fleet, for example). The higher up-front cost and lower running costs make hybrids very suitable for taxis, which tend to do high mileage.
“Advanced” vehicles: PHEVs and BEVs
Plug-in hybrid electric vehicles, or PHEVs, take the hybrid idea a step further. They still have an internal combustion engine and can be refuelled at petrol stations – but they also have a battery which can be recharged from the grid. Just plug ’em in.
Battery electric vehicles, or BEVs, ditch the engine altogether, and only run on electricity: no petrol or diesel involved.
From my thesis, available here:
In recent years, automakers have begun to focus more attention on PHEVs and BEVs… The distinctive feature of such vehicles is their ability to drive using electricity from the grid. Both PHEVs and BEVs incorporate a larger battery than those in traditional hybrids, and use this to power an electric motor. BEVs are entirely reliant on this motor, whereas PHEVs also include an internal combustion engine and can run on conventional fuels.
PHEVs and BEVs are significantly more efficient than conventional petrol or diesel vehicles, and have lower running costs as a result… PHEVs have smaller batteries than BEVs, and a limited electric-only range which may still be sufficient for the daily travel needs of many drivers. For longer trips, PHEVs will use their engine, giving them a comparable range to other cars.
By “range”, I mean the distance you can drive before you need to refuel or recharge the car. Essentially, the only real disadvantage of PHEVs (compared with conventional vehicles) is that they cost a lot to buy. For BEVs, there’s the high cost, plus the inability to take a long road trip without recharging or switching out the battery. Auckland to Hamilton might be possible, but much longer than that would be a stretch.
Plug-in hybrids have lower running costs than conventional cars – they use less petrol, and the electricity is pretty cheap too – and BEVs have even lower running costs.
Hydrogen cars are another type of advanced vehicle, discussed here, but I’ll be focussing on the PHEVs and BEVs from here on in.