How Many Elephants Can You Fit in an Electric Car?

As the first part in a series about electric vehicles (and you can probably guess where this is headed), let's find out how many elephants fit in an electric car. Why start with cars? Because the government would now like us to all drive around in them. Just like they first wanted us all to drive around in petrol cars. And then diesel cars. Hmmm.

Electric traction works much better than internal combustion traction, because electric motors combined with modern electronics are able to switch almost seamlessly from torque (for moving off) to power (for travelling at speed). There are far fewer moving parts, and with none of the considerable losses associated with combustion engines, electric traction is also very much more efficient.

But the first elephant climbing into the car will be asking, where does the electricity come from? With a train, supplying the power from a catenary cable is very much practical, albeit expensive to construct. But with personal, "go anywhere" transport that isn't practical. So a car with electric traction requires a mobile power source. That might be an internal combustion engine (ie a hybrid car), or it might be a fuel cell or battery. You may have noticed that battery cars are considerably more prevalent than fuel cell cars, and there's a good reason for that. The choices of fuel for a fuel cell car are methanol and hydrogen, both of which are problematic. Methanol is a liquid, but unfortunately it's both flammable and poisonous. Additionally, methanol fuel cells are very inefficient. Hydrogen is a highly explosive gas with a tiny molecule that can escape from the smallest fissure, and consequently is not well suited to use in a car. Hydrogen fuel cell vehicles are available, but myself I wouldn't want my personal transport to be fitted with two containers just behind the seat backs that are pressurised to 10,000 psi with hydrogen. Diesel oil only burns under special circumstances. Petrol is flammable, but at least it wont leak out of the smallest hole and explode at the least provocation (there has already been an explosion at a hydrogen fuelling station in Norway). When you consider that some people's idea of a replacement filler cap is an old rag, to me hydrogen doesn't look like a great option for mass use.

Note that neither hydrogen nor methanol are primary fuels. Both have to be manufactured (using electricity), making them both a means of storing energy, just like a battery. So of all the problems with electric cars I describe below, fuel cells only solve the problems that are due to battery technology (swapping them for other problems).

So why might we want to tank up rather than charge a battery? Because when you tank up a conventional car, the effective energy transfer rate (power) is many megawatts (ie the sort of power a Pendolino train uses), whilst the engine power is of the order of a hundred times less. That means you can refuel your car with petrol or diesel in a few minutes, and then drive it for many hours. If you want to do that electrically, to charge a battery at a rate of many megawatts, you have some serious problems to overcome. Firstly, the connector and cable would need to be very large, with enough copper to carry the current and enough insulation to allow for a high voltage (car batteries currently charge at up to several hundred volts, but Pendolinos run off 25,000 volts, which is OK on an overhead catenary cable, but not so great somewhere it can easily come into contact with people). Secondly, whilst battery technology is slowly getting better, what actually happens inside the battery in order to make it charge limits the charging rate. So a practical car recharger has to be scaled back, and that's why battery-electric cars take hours to fully charge. Even a Tesla Supercharger is "only" rated at 120 kW, which means it will take an hour to buy yourself another 300 miles. That means that for anything other than local journeys, operating a battery-electric car always going to be a deeply frustrating experience, as you can see in the following video about a road trip in a Jaguar I-Pace, by Brummy car enthusiast HubNut:

But even with that crippled refuelling power, imagine what would happen if every car refuelled by charging from mains electricity. The British national grid is notable for being very robust, but it is also running at very close to 100% capacity in winter. It makes sense to do that, because capacity costs lots of money. So if everyone currently driving a conventional car were to drive a battery-electric car, we would need to dramatically scale up our electrical supply infrastructure, at massive cost. You only need to look at your nearest road surface to know that the British government favours tax cuts over infrastructure investment. Perhaps that's why HubNut found the recharging infrastructure woefully inadequate, rather than someone in Westminster being aware of all the engineering elephants in the car.

The next elephant in the car is that even if we massively beefed up the power grid, where does it get its energy from? At the moment electricity in the UK largely comes from gas, coal having been deprecated as being just too polluting. But burning gas still produces carbon dioxide and oxides of nitrogen, both serious environmental issues. Nuclear waste is a £234bn problem in the UKWe could go the nuclear route in a big way, but then there's the problem of waste management (so far we have just been sweeping it under the carpet; the front cover of the June 2019 issue of the professional engineering magazine Eureka! had as part of the headline, "TACKLING THE UK's £234bn NUCLEAR WASTE ISSUE"). Plus of course there's the occasional inevitable nuclear disaster. Or we could casually say we'll get the energy from renewables. Renewables only supply a fraction of our current electrical needs, and the UK is utterly resistant to on-shore wind turbines. Germany is aiming for 100% renewables, and with North Germany half way there I can tell you they already have a lot of turbines. But most Germans do not drive an electric car. One company that provides "fast" electric vehicle chargers boasts that it equips charging stations with solar panels to provide the power. The Tesco petrol station in Selly Oak has eight fuel pumps. Multiply the Tesla charge rate of 120 kW by eight, and you have nearly a megawatt. A set of high quality solar panels mounted on the roof of your house can generate power at the rate of a few kilowatts, so delivering a megawatt would require an area of solar panels covering hundreds of roof tops. Moreover, that Tesco petrol station is capable of refuelling cars in a matter of minutes (including the time taken to pay for the fuel), not an hour or more, yet it still sees long queues. Clearly an electric charging station for mass use is totally impractical, and fitting solar panels to one to give drivers the impression they are running on solar power is greenwash in epic proportions.

If the electrical elephants in the car were not enough, there's also a materials elephant. Modern electric motors use rare earth magnets, and the bigger the motor, the bigger the magnets. Paradoxically rare earths are not rare, but widespread and reasonably abundant. Unfortunately they are typically not found in concentrated ores, which is what is needed for cost-effective exploitation. By far and away the biggest source of rare earths is China, but a combination of trade wars and China's desire to have its own industry add value to the raw material means that that source is restricted and risky. The alternatives are also problematic. If you are an aficionado of headphones, one rare-earth magnetic material you may well have heard of is samarium-cobalt. Cobalt is not only used in magnets, but also in batteries, including electric vehicle batteries. A smartphone or laptop battery uses a few grammes of cobalt. An electric car battery uses five or ten kilograms. I have heard it said that if all the cars in the UK were to be replaced with battery-electric cars, it would use more that than the entire world's production of cobalt, which is clearly a major issue in itself. By far and away most of that production comes from the Democratic Republic of the Congo, a country noted for violence and instability. According to The Washington Post, 17-40% of that production is dug out of "artisanal" mines. That may sound quaint, but the reality is children working underground with hand tools and no safety procedures. Cobalt is a conflict resource.

Another elephant in the car is battery life. Ever noticed how laptop and phone batteries lose their capacity? Would you want a car that you can only drive for ten minutes, like your old phone? How much will it cost to buy and fit a new traction battery? Would you balk at the price, and opt for a battery off Ebay that turned out to be disappointingly short on capacity (and lifespan)? Will it even be economically viable to replace the battery, and if it isn't, what will that do for resale values and the used car market? If you're thinking perhaps that a fabulous new, long life, higher capacity battery with a super-fast charging rate is just around the corner, keep in mind that batteries have the fundamental safety issue that they store all the energy in one container, as Dr Philip Mason (who gained his PhD in chemistry at Birmingham University) explains in this video. It's worth adding that in all my background engineering reading, I have yet to read about any battery technology that would suggest Dr Mason is just plain wrong. And If you're thinking perhaps fuel cells will address the lifetime issue, think again, as they too have lifetime issues.

So it would seem that electric cars come complete with quite a few elephants (in fact several more than will fit in an original Mini). Now it is just possible some new technology will come along that converts a safe-to-handle, easy-to-transfer material to electricity, but in all my engineering reading I have yet to see anything I consider promising. So for the moment I consider the idea of conventional cars going fully electric en-masse a flight of fancy. But let us suppose I'm completely wrong, and the elephants can be persuaded to get out of the car and go away. Climate change has been described as an existential threat. Switching conventional cars to electric traction just isn't going to do enough to address that. Cars simply require too much energy to manufacture, move about for a few years, and then scrap, being large, complicated, and heavy. That brings us to yet another elephant. A significant amount of the emissions from a car, any car, come from its manufacture and scrapping, so going electric isn't as big a saving on emissions as the emissions from driving alone would suggest. And being large, electric cars will still cause traffic congestion. Also, since the occupants do not have to supply any of the energy required to move them, electric cars will continue to promote the unhealthy, sedentary lifestyles that are undermining the NHS. We need to dramatically cut back on private car use, and do something different. If one makes that change, driving a conventional car (when there is no practical alternative) becomes dramatically less environmentally burdensome. For most local journeys, there are already better, more sustainable, more affordable solutions than electric cars, and I'm not just talking about our old friend, the acoustic motorbike. That will be the subject of part two of this series.

Photo credit: Brian Snelson, Flickr