Climate Change: the Potential for Electric Vehicles

In my last post, I discussed the need for action over climate change. Suppose we decide to be more responsible, what can we do? There are several issues, but the main ones include is a solution fit for purpose, which includes will the general population see it as such and does it achieve a useful goal, and is it actually possible? To illustrate what I mean, consider the “easy option”: scrap motor cars and replace with electric vehicles. At first sight, that is easy and you will probably think there is no technological advance needed. Well, think again on both of those. Let’s put numbers on the problem: according to Wikipedia, the number of motor vehicles in the world is 1.015 billion.

Now, to consider the issue, “fit for purpose”, in New Zealand, anyway, and I suspect North America will be worse, people drive fairly long distances at least some of the time. One solution to that problem is to make people stop doing that. This is from the “sacrifices have to be made” school. As it happens, energy consumption probably will have to be reduced, but that does not mean that we need some politicians to say which form of energy consumption is forbidden to you. If people must use less, they should have a choice in what form they give it up.

There are two “niches” of electric vehicle, and as examples I shall pick on the Tesla and the Nissan Leaf. The Tesla currently claims a 400 km range (and intends to provide a 500 km range) per charge, while what you get from the Leaf is highly dependent on driving conditions, but it reaches a little over 100 km with average city driving. Basically, the Leaf would be great for someone wishing to commute daily, but not use it for distance driving. As an aside, the dependency on conditions will affect all such cars; we know about this aspect of the Leaf because there is more information available as more Leafs have been sold. The difference in range is simply because the Leaf’s battery is much smaller (198 cells compared with Tesla’s 7,104).

So why doesn’t the Leaf put in more cells? That is partly because of the problem of charging, and partly because of price and suitability for a chosen niche. A review of electric vehicles in our local paper brought up these facts. There are statements that the 400 k type car be charged at home overnight, “just like your mobile phone”. Well, not quite. While that sounds easy enough, where are you going to do it? Your home may have a garage, so maybe there. The mobile connector comes with adaptors that permit charging at 40 amps. Um, does your house have 40 amp rating to your garage, or maybe 50 amp to be on the safe side because you don’t want to accidentally throw the fuse and be walking to wherever next morning? Our reviewer found that to fully charge such a vehicle with 400 km range using his garage power rating took the best part of two days. Using a fast charger as available here, it took 75 minutes. Yes, you can charge these batteries relatively quickly if you can deliver the required current. The reason the Leaf has such a small battery capacity is so that it can be charged overnight with the average domestic power supply, and it can also be recharged while at work if the owner can “graze” on some power supply. Needless to say, once someone published figures like that, someone else challenged them, and pointed out that a steady 7 kW overnight would do it and “nearly two days” was wrong. Unfortunately, power itself is not the whole story because the current has to be rectified and voltage has to be kept to within a specific range. Apply an over-voltage, and different chemistry starts up in the battery that is not reversible, which means you greatly shorten your battery life.

There is some good news on batteries, though. The batteries do decay with time, and while details are not available, one estimate is that Tesla batteries should still be 90% effective after 8 years, which is quite respectable, while the Leaf claims its batteries should last ten years in a workable condition. Thus we have two types of vehicles: an expensive vehicle that can do anything a current vehicle can do on the open highway, provided there are adequate rapid charging sites. Here “adequate” takes on significance; refilling with petrol takes a few minutes and sometimes there is overcrowding. Will there be enough cables if it takes 75 minutes? How much will “site time” charge?

Then there is the question of how you use it. Do you carry big loads? Ferry lots of children? Go off road, or go camping? If so, the current electric vehicle is not for you. So the question then is, for those who see the electric vehicle as all you have to do to solve the transport problem, are they advocating no off-road activity, no camping, no serious loads? The answer is probably, yes. So, do we want to give up our lifestyle? If the answer is no. are there options? Of course not everyone wants to do those sort of things, so there will most certainly be quite sizable niches that can be filled with electric vehicles. Finally, there will be one further problem: the poorer people cannot afford new Teslas, or even new Leafs. They own second hand cars and cannot afford to simply throw that investment away. The liquid fuel transport economy will be with us for a lot longer yet.

The next question is, is it feasible to replace all cars with electric vehicles? For the purpose of analysis, I shall assume everyone wants a Tesla type driving capacity, as the next step is to put numbers on the problem. The battery weight is listed as 540 kg, which means to do the replacement, we would need something approaching half a billion tonne of batteries. That is not all lithium, but it includes “a small amount of cobalt and nickel”. If we interpret that as about 2% the weight each of the batteries, we need about ten million tonne of cobalt and nickel. World production of cobalt in 2017 was about 110,000 tonne, while nickel was over ten times this. Both metals, however, are fully used now, and the cobalt supply is deficient by about two orders of magnitude if all cobalt was devoted to electric vehicles. Unlikely. Oops! That is more than a small problem. It is not a problem right now because electric vehicles comprise only a very small fraction of the market, but it is insoluble. There is a strict limit on the possible supply of cobalt because as far as I know, there are no cobalt ores. Most cobalt comes from the Democratic Republic of Congo, as a by-product of copper mining. There would also be a significant demand for copper. The Tesla has two motors, one of which is 300 kW, so considerable amount of copper would be used, but world production of copper is about 24,000 Mt annually, so that is not an immediate problem, but may be in the long term. The annual supply of graphite is 126,000 t. Given that there will be more graphite used than lithium, this is a serious problem, however there is no shortage of carbon; the problem is converting carbon to graphite. That is quite a subtle problem; as it happens I know how to get close to the required fraction of graphite, but as yet, not economically.

So there are technological problems. Maybe they are soluble, but doing so introduces another problem, as exemplified by finding an alternative to cobalt. Cobalt is needed to give the non-graphitic electrode enough strength that the battery will have adequate lifetimes with good charging rates. So that is probably non-negotiable. There are alternatives, but so far none match the current battery type used by Tesla. Further, to develop a new battery and test its lifetime over ten years takes: you guessed it; the last part alone takes ten years, assuming your first pick works. Therein lies the overall problem; politicians have wasted nearly 30 years on the basis that it was not urgent. However, technical development does take a long time. For that reason it is wrong to lazily say, electric vehicles, or some other solution, will solve the problem. They will most certainly help, but we have to back many more options.