In conclusion; Perhaps that is a legitimate question; why are we trying to develop the Otto engine or Diesel engine to run on hydrogen when it seems that they are already on their way out of society?

 There is no quick and easy answer to that. It is absolutely the case that the vehicle that uses fuel cell technology has a higher efficiency than an Otto engine or Diesel engine that has been modified to run on hydrogen.

 One way of looking at this is that we already have a large number of Otto engines and Diesel engines around the world. Still these engines largely dominate the market compared to electric vehicles.

Being able to replace these in a short time will be an impossibility, and at the same time it is of the utmost importance to take action very soon, because the global environment is threatened.

For factories to shift production from combustion engines to electric engines  Changing all factories today that produce combustion engines for our vehicles to instead produce electric engines will be a big challenge because it has to happen  rapidly. The same applies to battery production and the substances required for them. What we know today is that  those are only found in limited quantities in a few places in the world

In some parts of the world, it is not financially feasible, and will not be in the long term, to replace one's vehicle with an electric or fuel cell-powered one. Here the solution of rebuilding existing vehicles could be a good alternative.

The same applies to shipping, heavy traffic and airplanes, here the option of rebuilding existing engines for hydrogen operation could spare companies from large financial losses due to scrapping out a well-functioning fleet.

Yet another area today completely dependent on fossil fuel is the area of  enthusiast vehicles; on the ground, in the water or in the air. Within this area it would also  be welcome with an option to be able to continue using these vehicles. The same also applies to all types of motor-related racing.

Yet another aspect is  more of an emotional or nostalgic one. Some people find it difficult to scrap their old combustion engines and find a certain charm in hearing the sound of them.

It could be that one should regard the development of hydrogen fuel for the Otto and diesel engines as a transition until those vehicles have reached the point where they need to be replaced.

This replacement of new vehicles should at least be considered when we talk about commercial and private use cars.

 On the other hand, where there are no financial possibilities, hydrogen fuel could be a good alternative to be able to continue using vehicles that today burn fossil fuels, petrol or diesel.