By Peter P Dobbing
Most of us are aware of the electric car and the claims made by manufacturers exhorting us to buy the latest and greatest. Many such claims are likely to have at least an element of truth but it will be many years before a new technology can realize its full potential. It was a long time between the Wright Flyer and the first passenger airliner and even longer to the Boeing 747, the transistor was patented in 1948, but only in the late twentieth century were large scale integrated circuits in general use.
The electric car will eventually be fully developed and be comparable, at least in some respects, with today’s vehicles. Major claims by the pundits are that atmospheric pollution and operating costs will be much reduced, both claims may be true but we really need to consider just how much. Unfortunately, accurate information is difficult to come by, certainly manufacturers exaggerate and carefully edit the facts, but in time all will become clear.
Atmospheric pollution originates from many sources
The serious polluters are, in no particular order: passenger aircraft, heavy road transport, coal fired power stations in USA/Russia/China/Central Europe, farm animals, nature eg: Volcanos and forest fires and cars. If one considers the total pollution produced by a car up to a life of say 100,000 miles then 40% occurs during manufacture regardless of what propels it. So, some saving with electric drive but not quite what was hoped.
Now, consider operating costs, I can guarantee to any reader that in today’s world there is no such thing as cheap power, the population needs too much of it to be cheap. Before considering the efficiency of the motor car, it is worth reflecting upon the various sources of power. There are in fact two types, Primary Power – which needs no manufacturing process to be created but needs a process to be used and Secondary Power – which is created from a primary power but still requires a process to be used. In the former, we have the sun, wind, tides, coal, oil, gas and nuclear power and of these only nuclear power has any prospect of being a viable power source able to generate electricity for the long term needs of the world.
In the latter, we have electricity of which battery power is a sub set, heat and hydraulic engines, kinetic, potential and chemical energy. So, there are plenty of options but apart from nuclear, gas, oil and coal in the primaries and electricity, heat and hydraulic engines and chemicals in the secondary types. The rest, while technically interesting and good for generating headlines and political votes, are of very limited practical use and certainly uneconomic.
But returning to the motor car
Chemical energy by way of fuel cells is already used by the military for very specific applications but there are serious drawbacks to more general use. However, speaking as a research engineer with forty years’ experience, my money is on the fuel cell being developed over the next couple of decades and coming into universal use, especially for motor cars. With the electric car the current problem is with battery capacity and while this has improved in recent year’s, progress will inevitably become slower and more difficult.
A more serious problem to the Western world will be access to the rare earth materials used in these new super batteries and associated brushless motors. My current vehicle is a small family hatchback with an 80Kw petrol engine and can travel some 600 miles on one tank of fuel, cruise at 80mph as long as fuel is in the tank and has very low harmful emissions. In addition, the petrol engine is extremely reliable and cheap to maintain, having ample scope for further development.
A case in point are the new diamond tipped spark plugs which have a much extended life and performance compared with the previous tungsten type, finally of course, there is an established worldwide infrastructure able to support this technology. An equivalent electric car eg. the Nissan Leaf has according to the manufacturer’s data;
An 80KW electric motor, a 400 volt 30 KWh battery with a range of 107 miles or a 400 volt 24KWh battery with a range of 73 miles. These figures vary according to traffic conditions, temperature, battery age and the number of recharges – particularly fast recharges – the battery has undergone.
Public acceptance of electric cars has been slow to moderate as there are two fundamental problems, the range and the recharging facilities. The range figures quoted assume ideal driving condition, a moderate steady speed and a pleasant ambient temperature. Stop/start motoring, high speed cruising and temperatures above 70o C or below 10° C will significantly reduce these. Ranges are improving as battery technology advances and in some vehicles batteries of up to 700 volts are being fitted, but there are technical limits in doing this.
It takes about 3 minutes at a filling station to put enough petrol or diesel into a conventional car in order to travel say 300 miles. An electric car to travel the same distance would require three or more recharges. To even put the 24KWh of energy needed to travel each 100 miles into the battery in the same time (one minute) would require a supply of 1.5 Mega Watts, clearly an impractical requirement in the average 3 bed-semi or local filling station.
For an owner in the leafy suburbs with a drive, garage and a Type 1 Charger operating from a standard 13 amp outlet a 30 KWh battery can be recharged in about 10 hours, a 24 KWh battery in about 8 hours. More typical are type 2 chargers but which require a dedicated supply of 40 amperes for home use (giving 10 to 20 miles of range per hour of charging) or 80 amperes for commercial use. Installing such supplies are expensive and should electric cars become popular in a particular area, then the supply company will need to install additional network capacity, a problem already becoming evident in the UK.
People who keep their car in the street overnight (and this is probably the majority in the UK) have a more serious problem. They can either connect the charger to a convenient lamppost or run a live cable from their house, neither option is likely to be legal. Finally, there are high voltage direct current chargers available at some commercial charging stations that can top up a battery in a few minutes. Unfortunately, these have a serious impact on battery life and can invalidate the battery warranty.
With careful maintenance battery life can be up to 8 years with replacement costs being about £5,000 at present.
Regardless of the technology, one thing is certain: as petrol sales fall and the associated tax revenues diminish then governments will simply collect the same tax from motorists by other means. As I said before, there is no such thing as cheap power any more. There may be a little less pollution, at least in in the cities, but overall I suspect it will be hardly measurable.
I doubt that the electric car is the panacea to all pollution issues but they are a good idea, at least for now. Until we have something better, such as nuclear fusion, then most electricity used to recharge electric cars will come from fossil fuel fired power stations. Taking us more or less back to where we started.