You don't understand the thermodynamics of the situation. Fuel cells/electrolyzers are electrochemical systems with theoretically the same efficiency as batteri

You don't understand the thermodynamics of the situation. Fuel cells/electrolyzers are electrochemical systems with theoretically the same efficiency as batteries. If the alternative is just battery, then both have the same fundamental limitations. You are spending more energy than you are get back. At best, you are saying that for now, there is a more efficient way of doing it. But in the long run, that advantage will disappear. But the real point is that you can power things with wind or solar energy without depending on fossil fuels. While you can do this with both batteries and hydrogen, you avoid the heavy weight and the resource requirements if you go with the latter. You need only just wind, solar and water in order to create an an energy storage system. That puts the cost at potentially very close to zero. In the long-run, it likely will approach zero, just like how wind and solar power itself plunged in cost once they scaled up. As a result, it is likely going to be the dominant solution for most transportation needs.