The Electric Vehicle as a Solution to the Greenhouse Problem

Further to the discussion on climate change, in New Zealand now the argument is that we must reduce our greenhouse emissions by converting our vehicle fleet to electric vehicles. So, what about the world? Let us look at the details. Currently, there are estimated to be 1.2 billion vehicles on the roads, and by 2035 there will be two billion, assuming current trends continue. However, let us forget about such trends, and look at what it would take to switch 1.2 billion electric vehicles to electric. Obviously, at the price of them, that is not going to happen overnight, but how feasible is this in the long run?

For a scoping analysis, we need numbers, and the following is a “back of the envelope” type analysis. This is designed not to give answers, but at least to visualise the size of the problem. To start, we have to assume a battery size per vehicle, so I am going to assume each vehicle will have an 85 kWh battery assembly. A number of vehicles now have more than this, but equally many have less. However, for initial “back of the envelope” scoping, details are ignored. For the current purposes I shall assume an 85 kWh battery assembly and focus n the batteries.

First, we need a graphite anode, which, from web-provided data will require approximately 40 million t of graphite. Since Turkey alone has reserves of about 90 million t, strictly speaking, graphite is not a problem, although from a chemical point of view, what might be called graphite is not necessarily suitable. However, if there are impurities, they can be cleaned up. So far, not a limiting factor.

Next, each battery assembly will use about 6 kg of lithium, and using the best figures from Tesla, at least 17 kg of cobalt. This does not look too serious until we get to multiplying by 1.2 billion, which gets us to 7.2 million tonne of lithium, and 20.4 million t of cobalt. World production of lithium is 43,000 t/a, while that of cobalt is 110,000 t/a, and most of the cobalt goes to other uses already known. So overnight conversion is not possible. The world reserves of lithium are about 16 million t, so there is enough lithium, although since most of the reserves are not actually in production, presumably due to the difficulty in purifying the materials, we can assume a significant price increase would be required. Worse, the known reserves for cobalt are 7,100,000 so it is not possible to power these vehicles with our current “best battery technology”. There are alternatives, such as manganese based cathode additives, but with current technology they only have about 2/3 the power density and they can only last for about half the number of power cycles, so maybe this is not an answer.

Then comes the problem of how to power these vehicles. Let us suppose they use about ¼ of their energy on high-use days and they recharge for the next day. That requires about 24 billion kWhr of electricity generated that day for this purpose. World electricity production is currently a little over 21,000 TWh, Up to a point, that indicates “no problem”, except that over 1/3 of that came from coal, while gas and oil burning added to coal brought the fossil fuels contribution up to 2/3 of world energy production, and coal burning was the fastest growing contribution to energy demand. Also, of course, this is additional electricity we need. Global energy demand rose by 900 TWh in 2018. (Electricity statistics from the International Energy Agency.) So switching to electric vehicles will increase coal burning, which increases the emission of greenhouse gases, counter to the very problem you are trying to solve. Obviously, electricity supply is not a problem for transport, but it clearly overwhelms transport in contributing to the greenhouse gas problem. Germany closing its nuclear power stations is not a useful contribution to the problem.

It is frequently argued that solar power is the way to collect the necessary transport electricity. According to Wikipedia, the most productive solar power plant is in China’s Tengger desert, which produces 1.547 GW from 43 square kilometers. If we assume that it can operate like this for 6 hrs per day, we have 9.3 Gwh/day. The Earth has plenty of area, however, the 110,000 square km required is a significant fraction. Further, most places do not have such a friendly desert close by. Many have proposed that solar panels of the roof of houses could store power through the day and charge the vehicle at night, but to do that we have just doubled the battery requirements, and these are strained already. The solar panels could feed the grid through the day and charge the vehicles through the night when peak power demand has fallen away, so that would solve part of the problem, but now the solar panels have to make sense in terms of generating electricity for general purposes. Note that if we develop fusion power, which would solve a lot of energy requirements, it is most unlikely a fusion power plant could have its energy output varied too much, which would mean they would have run continuously through the night. At this point, charging electric cars would greatly assist the use of fusion power.

To summarise the use of electricity to power road transport using independent vehicles, there would need to be a significant increase in electricity production, but it is still a modest fraction of what we already generate. The reason it is so significant to New Zealand is that much of New Zealand electricity is renewable anyway, thanks to the heavy investment in hydropower. Unfortunately, that does not count because it was all installed prior to 1990. Those who turned off coal plants to switch to gas that had suddenly became available around 1990 did well out of these protocols, while those who had to resort to thermal because the hydro was fully utilised did not. However, in general the real greenhouse problem lies with the much bigger thermal power station emissions, especially the coal-fired stations. The limits to growth of electric vehicles currently lie with battery technology, and for electric vehicles to make more than a modest contribution to the transport problems, we need a fundamentally different form of battery or fuel cell. However, to power them, we need to develop far more productive electricity generation that does emit greenhouse gases.

Finally, I have yet to mention the contribution of biofuels. I shall do that later, but if you want a deeper perspective than in my blogs, my ebook “Biofuels” is 99c this week at Smashwords, in all formats. (https://www.smashwords.com/books/view/454344.)  Three other fictional ebooks are also on discount. (Go to https://www.smashwords.com/profile/view/IanMiller)

A Response to Climate Change, But Will it Work?

By now, if you have not heard that climate change is regarded as a problem, you must have been living under a flat rock. At least some of the politicians have recognized that this is a serious problem and they do what politicians do best: ban something. The current craze is to ban the manufacture of vehicles powered by liquid fuels in favour of electric vehicles, the electricity to be made from renewable resources. That sounds virtuous, but have they thought out the consequences?

The world consumption of petroleum for motor vehicles is in the order of 23,000 bbl/day. By my calculation, given some various conversion factors from the web, that requires approximately 1.6 GW of continuous extra electric consumption. In fact much more would be needed because the assumptions include 100% efficiency throughout. Note if you are relying on solar power, as many environmentalists want, you would need more than three times that amount because the sun does not shine at night, and worse, since this is to charge electric vehicles, which tend to be running in daytime, such electric energy would have to be stored for use at night. How do you store it?

The next problem is whether the grid could take that additional power. This is hardly an insurmountable problem, but I most definitely needs serious attention, and it would be more comforting if we thought the politicians had thought of this and were going to do something about it. Another argument is, since most cars would be charged at night, the normal grid could be used because there is significantly less consumption then. I think the peaks would still be a problem, and then we are back to where the power is coming from. Of course nuclear power, or even better, fusion power, would make production targets easily. But suppose, like New Zealand, you use hydro power? That is great for generating on demand, but each kWhr still requires the same amount of water availability. If the water is fully used now, and if you use this to charge at night, then you need some other source during the day.

The next problem for the politicians are the batteries, and this problem doubles if you use batteries to store electricity from solar to use at night. Currently, electric vehicles have ranges that are ideal for going to and from work each day, but not so ideal for long distance travel. The answer here is said to be “fast-charging” stops. The problem here is how do you get fast charging? The batteries have a fixed internal resistance, and you cannot do much about that. From Ohm’s law, given the resistance, the current flow, which is effectively the charge, can only be increased by increasing the voltage. At first sight you may think that is hardly a problem, but in fact there are two problems, both of which affect battery life. The first is, in general an overvoltage permits fresh electrochemistry to happen. Thus for the lithium ion battery you run the risk of what is called lithium plating. The lithium ions are supposed to go between what are called intercalation layers on the carbon anode, but if the current is too high, the ions cannot get in there quickly enough and they deposit outside, and cause irreversible damage. The second problem is too fast of charging causes heat to be generated, and that partially destroys the structural integrity of the electrodes.

The next problem is that batteries can be up to half the cost of the purely electric vehicle. Everybody claims battery prices are coming down, and they are. The lithium ion battery is about seven times cheaper than it was, but it will not necessarily get much cheaper because at present ingredients make up 70% of the cost. Ingredient prices are more likely to increase. Lithium is not particularly common, and a massive increase in production may be difficult. There are large deposits in Bolivia but as might be expected, there are other salts present in addition to the lithium salts. There is probably enough lithium but it has to be concentrated from brines and there are the salts you do not want that have to be disposed of, which reduces the “green-ness” of the exercise. Lithium prices can be assumed to go up significantly.

But the real elephant in the room is cobalt. Cobalt is not part of the chemistry of the battery, but it is necessary for the cathode. The battery works by shuttling lithium ions backwards and forwards between the cathode and anode. The cathode material needs to have the right structure to accommodate the ions, be stable so the ions can move in and out, have valence orbitals to accommodate the electron transfer, and the capacity to store as many lithium ions as possible. There are other materials that could replace cobalt, but cobalt is the only one where, when the lithium moves out, something does not move in to fill the spaces. Cobalt is essential for top performance. There are alternatives to use in current technology, but the cost is in poorer lifetimes, and there are alternative technologies, but nobody is sure they work. At present, a car needs somewhere between 7 – 20 kg of cobalt in its batteries, and as you reduce the cobalt content, you appear to reduce the life of the battery.

Cobalt is a problem because the current usage of cobalt in batteries is 48,000 t/a, while world production is about 100,000 t/a. The price is increasing rapidly as electric vehicles become more popular. At the beginning of 2017, a tonne of cobalt would cost $US 32,500; now it is at least $US 80,000. Over half the world’s production comes from the Democratic Republic of Congo, which may not be the most stable country, and worse, most of that 100,000 t/a comes as a byproduct from copper or nickel production. If there were to be a recession and the demand for stainless steel fell, then the production of cobalt would drop. The lithium ion batteries that would not be affected are the laptops and phones; they only need about 10 – 20 g of cobalt. Even worse, there are a lot of these batteries that currently are not being recycled.

In a previous post I noted there was not a single magic bullet to solve this problem. I stick to that opinion. We need a much broader approach than most of the politicians are considering. By broader, I do not mean the approach of denying we even have a problem.

This post is later than my usual, thanks to time demands approaching Easter, and I hope all my readers have a relaxing and pleasant Easter.