Will electric vehicles really take-over, and if so what are the implications…?
Maintenance and repair
Setting aside for the moment the safety implications of repairing and servicing vehicles with batteries containing dangerous levels electrically stored energy at over 600 volts (much the same as the London Underground trains use), the processes for maintenance and repair of these vehicles will change.
Without the need for a diesel or petrol engine or a gearbox to adjust the drive ratios for the limited rpm torque range of internal combustion engines, a large proportion of the work needed to service such vehicles will no longer apply. No oil or filter change – no engine/gearbox/clutch work at all, either to repair defects or for routine maintenance. Nor will there be any fuel lines, fuel pumps, fuel injection systems, or carburettors or a fuel tank. Steering, suspension, lights, tyres wheels and so on will, however, be much the same.
Transmissions system will also change. New systems will emerge – vehicles powered by a compact computer controlled electric motor at each wheel, eliminating altogether the need for transmission shafts have already been mooted. Nevertheless there may be more complexity with advanced computer control systems and an extra layer of technology with re-generative braking wherein the vehicle’s moving energy is turned into electricity to charge the battery by the motor or motors becoming dynamos both braking the vehicle and re-charging the battery at the same time – increasing efficiency.
With electric vehicles things should be easier, electric motors are more easily controlled than internal combustion engines. No fuel injection systems, or air control valves and so on – but there will need to be sophisticated software to monitor and regulate power to the electric motor(s), with inevitable regular software updates – which may not be provided free of charge.
The energy source – petrol, diesel or electricity…
If you think about it in absolute terms, storing 50 litres or more of a highly combustible liquid like petrol in a car’s fuel tank which could be subject to an impact rupturing the tank and causing an explosion and fire is a bad idea. Yet for well over a century now, that is what has been happening day-to-day, yet ironically most fires in cars aren’t caused by petrol leaks, but by the 12 volt electrical system – regular spontaneous combustion of many Vauxhall models caused by an electrical defect in the design being a case in point.
So whilst electric cars aren’t carrying combustible fuel, to ensure the range is not too dissimilar to that of petrol or diesel fuelled vehicles, they will need much the same amount of electrical energy as is carried in the fuel tank for petrol or diesel powered vehicles, but stored as electricity in a large slab shaped battery beneath the vehicle’s floor – that hefty battery, delivering energy at up to 600 volts, and many times heavier than a full tank of fuel – between 350 (770 lbs) and 500 kilograms (1,100 lbs) depending on whether it’s a family vehicle or a more luxurious limousine. Set against that, however is the weight of the engine, say 160 kg (350 lbs) for that family saloon.
The problem is, of course, that whilst you can smell a petrol leak, or even see the petrol seeping from a leak – if that high voltage energy somehow gets out of its box, there would be very little warning – perhaps a faint whiff of smoke. Yet people could still get hurt, by electrocution, or after a serious electrical fire. A fully charged battery in an electrically powered car may be less noticeable or conspicuous than diesel or petrol in a tank with their characteristic smells – but it can be just as dangerous.
Fantastically economical? Not necessarily!
Electrically powered vehicles are claimed to be much more economical than petrol or diesel engined powered vehicles. Official figures show that an electrically powered VW Golf, for example, delivers the equivalent of 150 miles to the gallon (mpg) if it were a petrol driven vehicle.
We’ve crunched the numbers and using a petrol pump price of £1.30 per litre, and an average cost for electricity of 14.7 pence per kilowatt, the published figures are almost exactly right – the author’s 1.4 litre Golf delivers on average 50 mpg, and the electrically powered version about 150 mpg, a 3 to 1 advantage in pence per mile.
Wow! You might think, that’s fantastic… but no! About 64% of the price paid for a litre of petrol goes to the government in tax. Apply the net, pre-tax price of petrol and the advantage reduces from 300% down to just under 10%.
Economic and environmental truths
Undoubtedly electric cars are better in numerous ways than those driven by internal combustion engines which have complex reciprocating components requiring a lot of oil for lubrication and petrol or diesel to provide power. Yet the real plus is the electrically powered vehicles’ lack of exhaust emissions, a massive benefit to the environment, yes, but only if their ‘fuel’ – electricity – is derived from a clean source, and, of course, is taxed in the same way diesel and petrol are now. That fuel tax money (rumoured to pretty much fund the NHS) has to come from somewhere… Clearly the government will need to address the issue of lost tax revenue before electric vehicles start filling more of UK motorists’ garages and car ports, and that will remove the price advantage. Perhaps the biggest challenge for the Government though, is how in future (when electrically powered cars become the norm for personal motorised transport), that extra electrical energy is generated.
How much extra electricity?
It is difficult to find any consistent analysis of how all the electricity required to power cars in the future could be provided if the vast majority of the country’s 35 million (approximately) vehicles were electrically powered. Would the country be able to produce enough electricity to cope – especially given the necessity to move away from gas and coal-fuelled power stations?
Both 2018 and it seems this year, are bumper years for low carbon electricity generation with more than half of all electricity produced from those sources. Yet should all cars require electricity there’s still a problem. Academic predictions seem to suggest that it will be difficult to meet the future demand for electricity created by an all electrically powered car fleet, without failing to meet international agreements on low carbon energy, whilst others are optimistically suggesting that householders will be generating their own electricity from solar cells and storing it in batteries in the home which will solve the problem in the longer term. A further optimistic projection is that improvements in electric car battery and motor technology will increase efficiency and reduce energy consumption. Clearly there’s a problem here, which currently doesn’t seem to have a viable solution – the thinking seems to be, “something will turn up”.
In the longer term, hydrogen fuel cell powered vehicles are thought to be the best option. There are no gaseous emissions and the only by-product is clear water. The snags are that energy is needed to produce the hydrogen, and a hydrogen/oxygen gas combination under pressure is potentially dangerous, but so is a tank of petrol – the Apollo 13 moon mission spacecraft explosion was caused by a spark in the fuel cell (providing electricity) igniting the hydrogen and oxygen and causing an explosion in the fuel tank; technological developments, however, could overcome these disadvantages in time.
The main problem currently though is infrastructure – there are only a half a dozen or so hydrogen fuelling stations in the UK, although ITM power does have plans to install as many more, but as a nationwide infrastructure it is very much in its infancy.
The 2040 deadline
It is government policy that all new vehicles sold in the UK by 2040 will have zero emissions. However, a parliamentary committee has said that the deadline should be set to 2032 (which seems just as arbitrary as 2040). But that doesn’t mean vehicles with diesel or petrol engines will be banned – there will probably be millions still on the roads at least until the middle of the century, including hybrid vehicles with a petrol or diesel engine able to charge the battery main drive battery, and of course petrol and diesel vehicles purchased between now and the deadline.
Electric powered vehicles – multiple choice!
So let’s get down to practicalities – what electrically powered vehicles are available on the market? Well, the Government’s Driver and Vehicle Standards Agency have provided a useful summary of the types of vehicles available
Hybrid vehicles have two different sources of stored energy – usually petrol and electricity.
The main reason for using hybrids is to reduce carbon dioxide (CO2) emissions.
Hybrids usually have smaller engines. The engine spends more time in the ‘sweet spot’ – the speed at which the engine runs most efficiently.
Driving wheels through a generator and an electric motor is more efficient than through a gearbox. The batteries regenerate on overrun, further improving efficiency.
On true hybrids (not range extenders or plug-in hybrids), all of the energy to drive the vehicle comes from the fuel in the tank.
There are 3 common types of hybrids used in light vehicles: series hybrid, parallel hybrid and series parallel
In series hybrids, the engine drives a generator, which in turn powers an electric motor to drive the wheels.
If the battery is fully charged, the extra energy from the battery can be used to supplement the power from the engine for a short while. This is usually for moving off.
On overrun, the battery is recharged and ready for the next time that extra power is needed. This is more often used on larger vehicles, for example, buses that do a lot of stopping and starting.
In parallel hybrids, the engine drives the vehicle mechanically through an automatic gearbox.
As with series parallel, the battery provides extra energy when needed through an electric motor. This is usually mounted between the engine and the gearbox.
This also acts as a starter motor and an overrun generator to charge the battery. These are sometimes called ‘mild hybrids’.
The Honda Insight was a parallel hybrid but they’re less common now.
Most modern hybrids are ‘series parallel’ or ‘full hybrids’ – sometimes called ‘strong hybrids’.
Series parallel hybrids can drive the wheels:
directly from the engine through a mechanical automatic gearbox only
by electric power only
by a combination of both
Electric vehicles (EVs)
These vehicles are driven by stored electrical power only.
Common examples are:
Range extenders are designed to run on batteries which are charged from an external supply. This power lasts for a limited period of time – longer journeys will start the engine.
However, the vehicle is always driven electrically from either battery power or from the engine-driven generator.
Common examples of range extenders include:
Volkswagen Golf GTE
Plug-in hybrid electric vehicles (PHEVs)
PHEVs are very similar to full hybrids, but they can also be charged from an external supply.
Common examples of PHEVs include:
Toyota Prius Plug-in
Hydrogen fuel cells
Hydrogen fuel cell technology is very complex.
In simple terms, it works a bit like a battery. Oxygen and hydrogen are fed into the cell. Under the action of catalysts, water (in the form of invisible superheated steam) and electricity are produced which provides energy to drive the wheels through electric motors.
There are only a few in the country at present, such as the Honda Clarity and the Toyota Mirai. There are also some buses running in London.
Hydrogen fuel cells carry the increased risk associated with the storage of hydrogen, as well as high voltage.
With acknowledgement to DVSA’s publication, ‘Hybrid, electric and hydrogen fuel cell systems: guidance for MOT testers’ for this information.
It wasn’t until just before and then after the First World War that cars took on a more or less standard layout of an internal combustion engine at the front with rear wheels driven through a differential.
Currently there’s a bewildering choice of electrically powered vehicles. The same thing happened when cars were in their infancy. In the late 1890s and early 20th century cars were not the same; there were steam powered cars and even electrically powered vehicles, and some had tiller steering with the driver and passengers sitting right at the front facing forwards!
Then after the advent of the Mini in the late 1950s with its front wheel drive an enduring trend was sparked which has continued until the current day.
The same thing is happening now with the proliferation of different electrically powered vehicles on offer – so it could take some time before an enduring trend emerges as to which technology supersedes the others. Only time will tell which of the various options becomes the norm for electrically powered vehicles into the future…