You are missing the point, if you think the efficiency of hydrogen is important. The whole point is that when it starts to be used, and it will, it will all be from solar. So it doesn't matter so much, what is lost to efficiency, the point is that what is put to use lowers temperature, the opposite of increasing it.
Nothing to do with the fossil fuels industry. In fact it is the fossil fuels industry who have generated all the misinformation about it. Even within academia, almost all of the research done on it is an effort to try to prevent it coming to credibility.
Water, appearing in the less than perfect hydrogen creation process in those books is called "pollution".
You work for them when you launch this false flag attack on it without even realising it, they are scared stiff of it coming to replace fossil fuels, is what I would say.
And how else will you keep planes in the air, and even in space?