Electric cars, hydrogen and synthetic fuels.

We are, I believe, in the stage of repentance. After making a stupid decision to convert the entire car fleet to electric, we are discovering that electric cars last too long and therefore less are sold, that we don't need much of the car industry, in the sense that we don't need so much related industries, and that the batteries are made by countries we don't like: China and the USA.

The last argument is absurd because even today's fuels cause a dependence on oil-producing countries, and we have lived with it quite well for more than a century.

The first two arguments are more serious, so now in countries where there are large automotive industries, the operators of related industries are starting to shit themselves because of the relative simplicity and incredible durability of electric cars. For an electric motor in those conditions, two or three million km are very manageable. Everything else will break first. But "everything else", in a combustion car it makes about 2700 parts, while in an electric car it makes about 1300 parts.

This does not mean, mind you, that car manufacturers will lose out. Thanks to the electric VW has earned more, but by selling fewer cars. The problem is that the related industries remain on their knees because fewer parts are needed.

So the proposal is, perhaps, to use hydrogen and "synthetic fuels" instead of electric batteries. This request comes from France, Italy and Germany, but the Japanese also agree.

What does it mean? Where does this mix come from? To understand this we must try to do a little chemistry (off the cuff).

You think hydrogen would be extracted from water, right? We see.

How much does it cost to extract hydrogen electrolytically from water? If we are in an ideal world. So, let's talk about moles and weights. (chemists shut up, I'm simplifying).

The atomic weight of oxygen is about 16. That of hydrogen is one. Therefore, if water is H2O , we have that 18 grams of water make:

Element Weight
Oxygen 16
Hydrogen 2

Thus, to have one gram of hydrogen we need nine grams of water.

How much does it cost (in energy) to dissociate 9 grams of water?

We need to know what the dissociation energy of water is, which is needed to do this:

2H2O(l) → 2H2(g) + O2(g)

If the table I found is correct, the dissociation energy is 15.89 kJ/g, so for nine grams we will need about 143 kJ of energy.

So to get our gram of hydrogen we spent about 143 kJ of energy.

Now, the problem is: how much energy can we get, also considering the entropy of the whole process, by burning hydrogen in oxygen?

This is where the combustion energy comes into play, which we need to do this:

2H2(g) + O2(g) → 2H2O(l) + energy

Apparently, we are left with an energy of The heat of combustion of hydrogen is about 141.8 kJ/mol.

now we do the count for grams, and we have that :

141.8 kJ/mol / 2 g/mol = 70.9 kJ/g

We have definitely not gained: our efficiency is 70.9/143, that is slightly less than 50%.

So no, your world where you use hydrogen as a carrier doesn't understand the idea of ​​extracting it from water. Unless you have energy to waste.

Let's try something else that contains a lot of hydrogen. methane.

Electrolytically dissociating methane is not simple. Unless you like big explosions, putting methane in a container with electrodes to separate hydrogen and carbon isn't a good idea.

The process is slightly different, and resembles a two-step process called reforming. But first let's look at how much hydrogen we get.

Methane, like water, always "weighs" 18. Only that they are distributed differently, in the CH4 formula

Element Weight
Carbon 14
Hydrogen 4

As you can see, an advantage can already be perceived, which is the density: with 18 grams of water we make only two grams of hydrogen, while with 18 grams of methane we make double the hydrogen.

The second advantage is energy, and is linked to the reforming process. Which can also involve electrolysis.

  1. CH4 + H2O → CO + 3H2
  2. CO + H2O → CO2 + H2

How much does it cost to extract a gram of hydrogen in this way? It depends on the technology used, they are 60/80 kJ/g. Now let's remember that by burning hydrogen you get 70.9 kJ/g.

We go much better with methane. But what is the problem? Why does methane give us a hand?. In reality it does not: in the cycle, in fact, we have a residue which is CO2.

Even if we stop halfway, we get a CO, a gas that isn't a very greenhouse gas but kills people pretty easily.

So yes, in any case if you want a hydrogen engine, it will probably be a methane engine, only that the carbon part is removed upstream, and you won't notice it.

Here comes the idea of ​​synthetic fuels. If you take normal LPG you could also make hydrogen with that, but this is not the point and I don't want to exhaust you: however LPG is a mix of Propane: C3H8 and Butane: C4H10, and as you can see of "H" there there is a lot of it, although not so much (in proportion to the methane). But the chemical pippone doesn't make sense, because they don't want to make hydrogen.

The point is the Fischer Tropsch process. https://it.wikipedia.org/wiki/Processo_Fischer-Tropsch

The Fischer Tropsch process was invented in Nazi Germany to make gasoline from coal. In reality, today, we prefer to use LPG because the process is more efficient and we obtain a cleaner fuel, and diesel is good for us:


Fischer Tropsch diesel is the transparent one, because it does not contain sulfur, and everything that pollutes diesel fuels. (except CO2, of course).

Therefore, it would be a matter of keeping the plants for LPG and its transport standing, and then making synthetic fuels with it.

These two solutions have one thing in common: you get a "clean" fuel, and it is, only because the carbon dioxide was used up first (not with synthetic diesel, which burns in your car), and allows to keep both the LPG or CNG distribution and the endothermic engine industry standing.

To recap:

  1. in case you make hydrogen with water, you waste a lot of energy.
  2. if hydrogen is made from methane, less is thrown away but CO2 is made
  3. if synthetic fuels are made, CO2 is always made in the same way, but they will explain to you that they are transparent like water.

In both of the latter cases, we continue to buy LPG or CNG (saving all related industries and making Putin happy), we continue to work on it (Making the shareholders of ENI, Basf, Heinkel, etc. happy), and you are given a fuel that isn't greener at all, it's just made to look like it.

Do you see how the counter-proposal “exclude hydrogen and synthetic fuel cars” makes sense now? Does it ring a bell now?

You could tell me that even in the case of the electric car things are like this, in the sense that we don't believe electricity is produced with the farts of Unicorns. On the other hand, however, how to produce electricity is a problem of industrial strategy, while the chemical formula of methane remains the same.

Anyway, here's what's under the counter-proposal of the "repentant of the electric".

The attempt to save the existing.

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