Since I was on a project that operated hydrogen and hythane buses back in the late 90's and early 2000's (and still does.....) I always find these kind of stories interesting.

At that time we were already making hydrogen using water and off peak electricity (no fracking gas needed...???). This project included both fuel cell and hydrogen combustion vehicles, the hythane vehicles were standard CNG buses, which could use up to a 20% hydrogen mixture, without major modification to the fuel system. They all worked fine and reduced emissions much more than was expected due to a "cooler" than expected burn, due to the extra water vapor created in the combustion cycle.

Later, after the Enron scam, the local utility built a number of "peaker" plant in the Palm Springs area, and used off peak wind power to generate hydrogen from water, which was stored on site, and which was then mixed with natural, and burned to generate "peak" electricity for summer afternoon air conditioning demand.

I've also seen many proposals and a few tests for using hydrogen and hythane on choo-choo's. These have involved both combustion and fuel cell technologies. It is expensive, and a lot more complicated to use, due to safety and fuel capacity issues for choo-choo's. And, despite this rather simplistic story narrative, this is still a long way off. This is truer today, than it was 20 years ago, because at Tier 4 and "beyond" technology emission levels the cost per marginal ton of health criteria pollutants (NOx, SOx, particulates) and "greenhouse" gases (mostly CO2)removed is so high. RR electrification also faces the same "economics" problem.

There are just so many cheaper ways, on a marginal cost per ton of emissions removed basis, to "buy up" health standard and greenhouse emissions from other sources, using much less costly/more cost effective technologies. One example is just replacing half of all existing air conditioning compressors over 15 years old with new technologies, which actually saves businesses, consumers, and governments "real" money from lower electrical consumption. These are vastly cheaper and more cost effective than almost anything we could do at even a "break even" cost, with todays much cleaner choo-choo technologies.

Ironically, if we were still using a fleet of pre 92 completely un-regulated loco's it would be far more cost effective to electrify, and/or use hydrogen technologies. That was the case when I did my first RR electrification study, but over my career since then, we have found ways to seriously clean up over 90% of the health standard pollution from choo-choo's, in a more cost effective way.