https://www.sciencedirect.com/science/article/abs/pii/S0360319918308371 https://www.sciencedirect.com/science/article/abs/pii/S03603... The maximum possible ef

https://www.sciencedirect.com/science/article/abs/pii/S0360319918308371 https://www.sciencedirect.com/science/article/abs/pii/S03603... The maximum possible efficiency of a fuel cell is 100%. It follows directly from the realization that they are not limited by Carnot's cycle. Hence why in the long run, it is pretty much a guarantee that a hydrogen based solution will win out. If two solutions are equally efficiency, than the only that is vastly cheaper will be the solution. These types of comparisons of efficiency comparisons are ultimately just nonsense. Most of them are all over the place, from 2x difference to sometimes 10x or worse. That's because they are just cherry-pick numbers in order to create a narrative. It is not really based on any sort of real analysis. In reality, a large portion of renewable energy is lost or never utilized, largely due to its intermittency. Without any way of storing it, renewable energy is very inefficient overall. They pretty much always have to be backed up by fossil fuels today. Adding a way to store vast amounts of it, such as hydrogen, makes renewable energy significantly more efficient and eliminates the need for fossil fuels. But if you make that realization, then it also becomes obvious that running cars off of hydrogen does not imply any kind of major loss of efficiency. The problem basically becomes irrelevant, since you are running cars off of energy that would've been lost anyways.