The truth about electric cars

It’s interesting to note that electric cars hit the roads well before gasoline driven cars did. But they fell out of favor, and gasoline won over batteries and all else as the energy carrier of choice. Why? Pure greed and power of the oil companies? Hardly…

I have kept silent for a long time, but I feel I must now contribute a little bit to public knowledge and clear up some myths and misconceptions surrounding these issues, and de-base the outrageous claims made by manufacturers of electric vehicles! To avoid any misunderstandings, I would like to state that I'm in no way connected to any fossil fuel interests, and that I would like most dearly to see the present cars replaced by something better and more ecological. But I hate seeing ignorant people misled by other, more clever people, who don't see anything wrong in misrepresenting some facts and in obscuring others, in order to sell their products.

First myth: Electric cars have lower operational cost than gasoline cars.

Your present car needs 10 liters of gasoline to go 100 kilometers. At 1.3 Euro per liter, that makes 13 cents per kilometer. Our super duper electrical car needs only 15 kWh of electricity for those 100 kilometers. At 8 cents per kWh (night time rate), that's only  1.2 cents per kilometer! Look how much money you will be saving!

The calculation in itself might be correct, but it colors some facts, and completely omits other, very important ones! For starters, the 10 liters per 100 kilometers stated there are valid for a large, heavy car, which can take five passengers and a significant amount of load, has air conditioning, and is being driven fast. The 15kWh per 100 kilometers instead are for a tiny minimal electric car that seats two people, with no cargo, and goes at half the speed of the gasoline car. Talk about comparing apples to oranges.

Will you come home in your electric car, park it, then wait until midnight or whenever the electricity rate drops (if it does at all!), and then plug it in? Most people won't have the discipline to do that, nor the technical inclination to use a timer, even if the latter is easy to do. Also, there will be many cases when you will be forced to recharge your car during the day, at high electricity cost. So the 8 cents per kWh might turn into 20 or more.

But electricity is not nearly the most important factor in operational cost! What the electric car manufacturers try to hide from the clients is the huge operational cost caused by battery replacement! Unfortunately the batteries don't last very long, and they are expensive. A typical lead acid battery used for an electric car might store 1kWh for 200 times before its lifetime is over, and might cost  80 Euro. You need several of those batteries for a small electric car, of course. Anyway, with 80 Euro worth of battery storing a total of 200kWh over its lifetime, you have 40 cents per kWh of stored energy, in battery replacement cost alone!!!  So, the battery replacement cost for a tiny electric car is about the same as the gasoline cost for a big conventional car! How's that for an important fact hidden by the seller?

And that's considering lead-acid batteries, which are the least expensive of all available options! They are heavy, use nasty sulfuric acid, and so some electric car makers are tempted to use better battery technology, such as one of several nickel chemistries, or even lithium. Nickel lasts longer than lead, lithium lasts about the same or less than lead, but both are more expensive than lead. As a result, nickel batteries cost more per kWh stored over their lifetime, and lithium batteries cost very much more!

So, the very simple fact is that for an electric car, battery replacement cost alone is higher than the entire operational cost of a similarly sized gasoline car!

 It comes as a minor, insignificant addition that the electric car makers don't mention the losses due to charge efficiency of a battery not being 100%. The battery needs more charge (amperehours) put into it, then it will give back, and it needs to be charged at a higher voltage than what it will give back. The two things compound to make a battery about 70 to 80% efficient, at most. Also the chargers have some losses, even if these are small. As a result, if the manufacturer states that his car will go 100 km with a charge of 15kWh in the batteries, you will need to buy about 20kWh of electricity to recharge the car after that.

The bottom line is that the total operational cost of an electric car is easily 30% higher than that of a gasoline powered car of the same size and weight, AND that the electric car can take only half as many passengers, because the rest of its room and loading capacity are used up by the batteries!
 

Second myth: Electric cars don't pollute

Now add the need for large batteries. These are mostly made from toxic materials. The most common battery technology is based on lead and sulfuric acid. Both of them are pretty nasty. Sure, in a properly managed system, the worn batteries will be returned to the factory and recycled to a high degree. Let's hope this cycle will work…
 

Third myth: electrical cars are sustainable

So, electric cars will mostly be using electricity generated from non-renewable sources. Their advantage might rest in better overall efficiency. It's possible that burning a fossil fuel in a modern, highly efficient combined cycle plant, making electricity, charging batteries, and then using the electricity in efficient motors, will end up being just slightly more efficient than burning the fossil fuel directly in a conventional car engine. In any case, the gain isn't much: Maybe 35% overall efficiency instead of 32%.

Hybrid cars:

The answer depends on how the hybrid car is used. In city stop-and-go traffic, certainly it helps in reducing gasoline consumption. After all, a big part of the energy spent there is usually wasted by braking! Also, someone driving often over hilly terrain might make a significant fuel saving by recovering energy while going downhill and using it to help go uphill again. So, at least in principle a hybrid car is a good idea. Of course, the control of the system must be intelligent enough to make it work well! If you are going downhill and your battery is full, there is no way to store the energy and you have to waste it in the brakes anyway. And if you are going uphill too long, the battery gets exhausted and you have to drive on the small gasoline engine alone, with the penalty of having to carry the heavy battery and electric machine along!

And of course, if you are driving at constant speed on the highway from one city to another, the whole electric stuff in the hybrid car is completely useless ballast. The fuel efficiency of a hybrid car on the highway is lower than that of an equivalent conventional car. The makers of hybrid cars just don't like to tell you this fact!

There is also that other basic fact already explained for pure electric cars: The cost of replacing the battery when it wears out is more than the cost of the fuel you can ever save! Every Euro you save on gasoline will make you spend several Euro on battery replacement. This is because hybrid cars use quite expensive batteries, which is a necessity due to the high charge and discharge rates put upon them. A typical hybrid car might save 10% of the gasoline in average use, and the battery will ideally last for about 150000km. That means, the hybrid car might save 1200 liters of gasoline over the lifetime of the battery. That's a saving of 1500 Euro or so. Great… but the battery for the hybrid car costs 3000 Euro! Oops! Where has my saving gone?

So, if anyone intends to buy a hybrid car in order to save money in the long term, he's on the wrong track. If instead the idea is to cause less pollution, accepting the fact that the operational cost will be higher, then there is a good chance that a hybrid car is a good idea. It might save 10% of the exhaust gas in typical use, which might be more significant than the additional pollution caused by the making and disposing of the battery, the additional electric machine, control electronics, the additional tire wear due to the added weight, etc. With some luck, the total improvement in environmental impact of a hybrid car over an equivalent conventional one might be in the neighborhood of 3% or so. If that's worth paying perhaps 10% more money overall, has to be answered by each prospective owner.

I fear that many owners of hybrid cars will end up not replacing the battery when it's worn, turning their flashy modern hybrid cars into de-facto conventional cars with some fancy ballast added. After all, the car will still move even if the battery is dead… Cars that get this treatment will end up having all the disadvantages of conventional cars combined with the disadvantages of hybrid ones!

What about hydrogen?

Sure, the oceans are full of water, and water is about 11% hydrogen. But the hydrogen in water is in its absolutely lowest possible energy state, totally oxidized! To make hydrogen gas, you have to tear away the hydrogen from the oxygen, and that needs a lot of energy. Later, when you burn hydrogen, it simply binds to oxygen again, forming water, and giving back most of the energy used to separate it from oxygen before.

So, hydrogen does not solve any energy shortages. It only provides one more way to carry energy from one place to another.

Hydrogen as an energy carrier has, like most things in this world, advantages and disadvantages. The main advantage is that you can either burn it to generate heat, or power a combustion engine, or you can put it into a fuel cell to generate electricity. Several other fuels have the same flexibility, but hydrogen adds the advantage that the only combustion product is water, so there is no pollution from using it – just a steam jet making everything damp! Of course, there is the pollution generated when obtaining the energy needed to make hydrogen…

The disadvantages of hydrogen as an energy carrier are mostly related to it being a gas. It's very hard to liquefy and to keep in liquid state, so that this option is not practical for cars. It's used in some rocket engines, though, where cost and complexity are minor issues and energy density means everything. In cars, hydrogen can be carried along either at very high pressure in a heavy, thick-walled steel bottle, or adsorbed into highly porous substances, or chemically bound as a hydride. In either case, the relationship between energy contents and weight for a hydrogen tank is hugely worse than for a tank containing a conventional liquid fuel!

Comparing  the options

A typical car's tank full of gasoline might weigh 40kg. That's about 10kg for the tank and inlet, and 30kg for about 40 liters of gasoline. The gross energy contents of this amount of gasoline is about 380 kWh. Now the efficiency of a gasoline engine is really poor, around 30 to 35%. As a result, our tank full of gasoline will give us around 130kWh of mechanical energy at the wheels of the car, plus all the heat we might ever care to have, and some more!  That's 3250 Wh of effective mechanical energy per kg of fuel plus tank.

Diesel fuel is even better, because the fuel has a slightly higher energy density, and the diesel engine is noticeably more efficient! It might get about 4000Wh/kg at the wheels. The diesel engine is heavier than either the gasoline engine or a good electric motor, so that's a negative point for it. By the way, the more common and cheaper electric motors are heavier then either the gasoline or diesel engines of the same power!

With batteries the situation is much more meager. Gross energy contents of a fully charged, new battery varies from about 40Wh/kg for lead acid, to about 200Wh/kg for lithium. Considering a motor efficiency of 80%, at the wheels we get from 32 to 160Wh/kg. Folks, that's 20 to 100 times worse than gasoline!!! This is why electric cars have such a severely limited range. Even stretching the amount of batteries carried to the absolute limit, electric cars have a hard time going further than about 80km before the battery is empty. Any cheap, simple gasoline car can go at least 400km on a single tank, many can go 800km, and should it be necessary, you can easily add additional tanks to extend the range to a few thousand km!
Add to this that the battery has the rated energy density only while it's new! As it ages, the energy density drops, until it's simply no longer acceptable and the battery has to be replaced. A gasoline tank instead is restored to full original energy density every time you fill it up! This is another difference the manufacturers of electric cars hate to let you know.

Hydrogen is somewhere in between. Per se, hydrogen has excellent energy density, roughly three times as good as gasoline! The problem lies in the tank. You cannot simply pour it into a thin walled container and keep it there until needed. In the best practical hydrogen tanks, based on porous substances that store hydrogen in chemically bound form, the energy density per weight is a little bit better than the best batteries, which makes it still at least an order of magnitude worse than a gasoline tank. Development in this field continues, but it seems unlikely that hydrogen will ever meet the efficiency of liquid fuels in this regard. For that you would need a storage system that has at least one quarter of its total weight in stored hydrogen. The technology might become “good enough”, though.

Many people are waiting for battery makers to come out with a new battery type that can meet or even beat gasoline as an energy carrier. Well, if you are among those hopefuls, I suggest you prepare for a very long waiting time! I guarantee that you will never see such a battery.

The reason is quite simple: Gasoline is a complex mix of different chemicals, which are all based mainly on hydrogen and carbon. Both the hydrogen and the carbon are in a high energy state. When burning gasoline, you pull lots of oxygen from the air, you break up the high energy ties between hydrogen and carbon, and replace them by very low energy ties between hydrogen and oxygen (water), and carbon and oxygen (carbon dioxide). The whole energy difference is yours to enjoy. Every hydrogen and carbon atom in your tank is used to generate energy. Only the tank itself, weighing a few kg, is inert mass. That's more than compensated for by the fact that for every kg of hydrogen you burn, you are using 8kg of oxygen, and for every kg of carbon, you are using 2.7kg of oxygen. All of that oxygen is coming from the air, and you don't have to carry it around! So, for a gasoline tank that starts weighing 40kg and ends at 10kg, you are using the energy contained in roughly 150kg of active reaction substance!

Take a lead-acid battery now. You have an inert plastic container. In it is an inert structure of very heavy lead grid plates. Smeared into the grid openings is a paste containing the active substances: Lead oxide in the positive plates, porous lead dust in the negative ones. These active substances need to be bound in some way, so there is additional inert material. All of this plate-and-paste assembly is immersed in the electrolyte, which is composed by 80% of inert water, the rest being sulfuric acid, of which a fair part is used in the reaction.

During discharge, sulfate ions from the sulfuric acid attach to lead at the negative plates, while oxygen ions detach from the positive plates and go into the solution to replace the sulfate ions. So, to get the energy from just a few atoms changing oxidation state, you must move around a lot of atoms which don't really contribute, and you can watch another huge amount of auxiliary stuff sitting around and doing nothing! In addition, the atoms you are moving around are pretty heavy ones (sulfur, lead!), and they don't store a dramatically different amount of energy than the much lighter carbon and hydrogen.

In other battery types the chemistry is different, but the basic problem is the same.

So, that's why batteries have so much less energy density than a tank full of gasoline. There isn't really a way to eliminate the problem from the root. And there is only so much that can be done to improve batteries. The active materials can be chosen to give the biggest energy storage for the least weight. This is where lithium comes in. The auxiliary structures can be reduced to the bare minimum. The electrolyte can be concentrated. But even so, you end up carrying ALL the active substance, not just a third of it like with gasoline, except if you use a metal-air battery, but these are not presently viable for powering cars; you carry around lots of supportive material that's not needed for gasoline; and even lithium has a worse ratio of energy to weight than the hydrogen that makes up so much of gasoline!

That's why I'm pretty positive that batteries will never come anywhere near the energy density of a tank full of liquid fuel.

By the way, a battery still weighs the same when it has been discharged. An empty fuel tank instead has lost most of its weight! That's another little point that improves the performance of conventional cars over electrics. Oh, and I almost forgot: If you want heating in an electric car, you need to drain additional power from the battery. The electric motor simply doesn't produce enough heat. In a gasoline car, instead, you can take as much heat as you want from the waste heat of the engine. It doesn't cost extra.

What should we do now, that Manfred has demolished electric cars?

Another point is speed. At the typical speed most traffic happens today, excepting gridlocks, most of the energy is used to overcome aerodynamic resistance. And this resistance rises dramatically with speed! I sometimes look out of my window, and watch all those crazy people, zipping forth and back at totally non-human speeds. Why not slow down drastically? Enjoy all those little beautiful things we can see when going slow, but cannot when speeding? Enjoy greater quietness, safety? Enjoy life? If we move along at bicycle speed, we can save easily 70% of the cost, fuel, pollution, and almost 100% of the risk we take for normal in our excessively fast life!

These simple measures can save more energy and pollution than any technology change can. But we should also improve the technology of our cars. Quite frankly, cars are a great invention and allow to do things that would be unthinkable without them. But why, please, does a car intended for 4 people have to weigh four times as much as these 4 people? I think we have more than enough technology available to make small, lightweight cars that can save two thirds of the fuel just because of being smaller and lighter! And why always use cars for 4 to 5 people, when driving alone? Why use pickup trucks when not transporting any heavy cargo? That's an absolutely ridiculous waste of energy! In average, these days each car is occupied by 1.3 persons. That means, the average payload of a car is at most 120kg, but the average car is designed for a payload of 500kg and weighs 1200kg when empty! What a waste!!! In average we are moving 10kg of car for every kg of useful load! This figure urgently needs improvement. Electric cars with their heavy batteries are not the way to do that. Modern, small, lightweight cars powered by liquid fuels are a much better bet.

It's in this area where we can get good ideas from electric car makers. Given the heavy weight of their batteries, these manufacturers start by making their cars as small and lightweight as possible. So, why not take such an ultralight car, remove the batteries to make it REALLY light, then replace the electric motor by a tiny gasoline engine and install a small gasoline tank? The result would be a lightweight car for two people, which can carry a lot of load (unlike when it was electric), which has a range 10 times as far as when it was electric, has much better performance, and which has a really low operational cost, one third of a conventional “big” car and one tenth of the electric car.

It's strange to see that some people are perfectly willing to use a small electric car, but are afraid of using an equally small gasoline car! They claim safety reasons. Sure, driving a battleship is safest for you, while at the same time it's most risky to those around you. How far can egoism go?  Now consider that the small car becomes much safer after removing the heavy batteries. Really, I would not like to be in a crash driving a small, weak car, with 300kg of lead acid batteries behind my back! That sounds like sure death, even if the crash happens at barely 20km/h. Instead, a crash in that same car, at the same speed, but without those batteries in the back, would be pretty easy to survive.

In the defense of some electric car makers, I have to state that many of them do consider this risk, and place the batteries under the people, rather than behind them. That's much better indeed. Still, driving a car without such a heavy mass is safer.

Speaking of risk, a car crash with spilled gasoline is very dangerous. But car makers have learned to place the tanks at the car's most protected spot, minimizing the risk of rupture. Batteries instead are large and heavy, so they cannot be placed in a sweet spot, and they will rupture in the event of a crash, spilling their acid. If you ask me, I prefer getting soaked in gasoline rather than in sulfuric acid! Soaked in gasoline, I have a good chance of  escaping with little harm, unless the stuff ignites. Soaked in sulfuric acid, I will certainly die from the severe chemical burns.
By the way, nickel batteries don't use acid. Instead, they use potassium hydroxide (caustic potash), which is chemically very similar to caustic soda. You probably know that stuff and what it does to skin. Not nice…
And lithium? Well, crush a lithium cell and it will explode with a surprising violence. After that explosion under your seat, it's pretty irrelevant whether or not you get any of its electrolyte spilled over your body!

 I know no cases of sudden explosions of fuel tanks in cars. Normally it cannot happen, because there is no oxygen in the tanks. Just gasoline and its vapor. It can't explode without oxygen! Batteries instead contain everything needed for a nice, juicy explosion. Lead acid batteries form oxygen and hydrogen. The amount is small, but if a spark jumps inside a cell, which happens sometimes when a connection loosens because of vibration, the explosion is violent enough to tear the battery apart and spill the acid. And lithium batteries are particularly dangerous, because there are many mechanisms by which the main active substance can explode! Just look at the news of exploded laptop batteries, and extrapolate the damage to the battery size needed for a car! Not nice, really…
 

So, is it gasoline forever?

Hopefully not. I would prefer something that stinks less! But indeed I think that liquid fuel is the way to go for the foreseeable future. This liquid fuel might be oil-derived, while oil lasts (apparently not much longer). It might be organic and 100% renewable, such as vegetable oils or alcohol.  It might be synthesized from other energies; for example, synthetic fuel compatible with gasoline engines was used in Germany as early as the 1920s. So, the end of fossil oil does not mean the end of gasoline as an energy carrier! This has to be kept in mind. I can perfectly imagine the world 100 years from now, with fossil oil basically exhausted, but gasoline driven cars, based on the same technology as ours, still going strong, with their fuel being synthesized partly from coal and otherwise straight out of water and carbon dioxide from the air, using solar, wind and mostly nuclear energy.

 Good or bad, I won't dare to say. But clearly there is more future in this, than in battery or hydrogen-driven  cars!

Update!

Battery improvements

Motors

There has been a change in motor technology. Antique electric cars, from the first ones built much more than a century ago, until those of the 1970s and 1980s, the motor of choice was the universal series-connected brush-type motor. It's relatively simple, inexpensive, robust enough, and has a speed/torque curve that lends itself very well to vehicular use, without needing any electronics. In old cars it was controlled simply by connecting it in series with several switchable resistors, while more modern cars used primitive electronics to control it by slow pulse width modulation. 

The Achilles Heel of these motors are the brushes. They cause loss, they spark, they are sensitive to dust, and they wear out. If proper maintenance isn't done, severe damage happens. For all these reasons such brush type motors were replaced by brushless types, as soon as power electronics had come along far enough to allow making the necessary, much more complex controllers, at a reasonable cost. Brushless motors can be made in many ways. A common one is to place coils in a three-phase arrangement in the stator, and simply use several powerful permanent magnets as the rotor. This forms a synchronous AC motor, which is very often but incorrectly called "brushless DC motor". To run, it requires an angular position sensor, and an electronic controller that applies a controlled current and voltage, at controlled times, to each winding. These motors are highly efficient, very controllable, but the permanent magnets tend to make them somewhat expensive. Specially if small size and weight is demanded, very strong and quite expensive rare earth magnets need to be used.  Still, this was the motor of choice during some time.

But recently the electric car industry seems to prefer another old-fashioned industrial workhorse: The asynchronous AC induction motor. Its construction is much like the previous type, except that it uses no magnets. Instead its rotor is made from silicon steel with a simple, robust shorted winding. These motors are much less expensive than the synchronous ones. You will find them in fridges, fans, water pumps, vinyl record players (remember them?), all the way up to giant versions used in heavy industry. There are many good reasons to use them in electric cars too, and several car makers are using them.

Exaggerated claims

The charging problem

Price

A very wrong trend to gigantism

Lack of variety and specialization

Safety

New battery types

The trend to complex systems

Lack of maturity

Practical experience

Political decisions

Next update!