Walking the last mile would do Brad Templeton some good.

Then again, we do have to worry about the San Andreas fault.

Pretty clear and obvious that hydrogen can't compete on efficiency grounds vs batteries for cars.
For aircraft I presume the upper limit for propeller driven aircraft speed would mean that burning it in a turbine would also be considered. While the efficiency would be lower, the advantages of being a renewable energy source and lighter fuel load (longer range) still apply.
Where do ships fit here? Weight is far less crucial than for aircraft, but I'm guessing fuel as a percentage of mass is higher than for a car. Batteries might be too bulky as well as heavy for shipping. Does the efficiency of hydrogen along with its green qualities do enough to give it an advantage over diesel?
Too lazy to look it up but do ships actually use diesel electric with power station like efficiency, or just plain diesel and ICE type efficiency?

Your analysis doesn't cover the production of hydrogen from biomass and natural gas with carbon capture and sequestration of carbon dioxide. High temperature hydrogen turbines and SOFCs will allow the latter options to be economic. Battery electric vehicles won't compete with HFCVs where the vehicle weighs a lot and if the range is great which characterizes the U.S. marketplace. BOTH require large batteries vs storage tanks. Also many vehicles are parked on the street or parking lots where it will be difficult to recharge. RNG from biomass will allow our homes and industry to remain unchanged.

Brad, I think your analysis is incomplete and a tad off the mark. Efficiency arguments alone are not particularly decisive. What matters is the price of hydrogen (can it be produced at or below the petroleum equivalent price) - one kilogram of hydrogen will power a FCEV for about 100 kms. And what does it cost to purchase a FCEV. Yes - efficiency gains can bring down the H2 price a bit, and yes, gains in fuel cell efficiency will take the car farther on the same amount of of H2. But these are just incremental factors. That internal combustion engines in automobiles are not much more than 20% efficient has never been a decisive factor for the fossil fuel economy.

Their experiment is to take watered out hydrocarbon reservoirs which have no current economic value and gasify them underground by introducing oxygen, which would mean the hydrogen would float to the top and be harvested with zero carbon emission. The hydrogen cost would be as low as $.10/kg. They did a proof of concept, but it will be a year before they attempt production at commercial scale.
The hydrogen would be produced wherever there are deep reservoirs of hydrocarbons or coal so it would be in a lot of places in certain countries. I would love to read comments about how that would affect hydrogen's possibility in the automobile market.

Proton would not create any mess like solar does, because everything not used remains underground. Gas lines transporting hydrogen would require embrittlement but their hydrogen carrying limit would be stuck at 15% although the furnaces could handle more. Oil pipelines can handle hydrogen with the oil so no adjustments would be needed for that although they would end up producing hydrocarbons. Hydrogen is also trucked or sent by rail currently.
I don't know anything else about how it would be transported, and it is early days.

I generally agree with the state of play you presented in your November 2019 articles on Hydrogen applications. However there is an area where green hydrogen's advantages will see the mining industry being an early adopter. Could be the basis of a follow up article for you? This space is rapidly progressing and all the large mining companies are backing it as a diesel replacement.