In my opinion the only sensible source of carrier hydrogen is blue hydrogen with sequestration, mostly from natural gas or what's removed from degassed Bakken or Eagle Ford crude. (The CO2 drops out fairly early in the compression to storage.)

Green hydrogen is in my opinion a boondoggle compared to using the 'production energy' directly as electricity or in other ways. I won't go so far as to say ammonia-cycle would be more sensible (I don't think any ammonia cycle makes sense in the first place) but from a purely financial standpoint...

While I'm on the side of line electrification all the way, I can see uses for battery-electrics and, if the units CPKC owns are found viable, even hydro fuel cell -- specifically, being thrown onto consists with pantograph-electric locomotives to get through towns whose local governments are resistant to electrifying. Have them shut off or just using whatever they can mooch off the lead engine, then when the wires end 5 miles off the outskirts of NIMBYton, UT, kick the battery-electrics up to full speed to make sure the train doesn't stall from coasting before it can get more power, then recharge using the lead engine's power.

You'd need a coupler design that can transmit power, or add in sockets alongside the brake hoses, though.

Much of the 'correct' answer is either implicit in, or can be reasonably easily deduced from, the study that Garrett AiResearch did starting in the late '70s, with the 'dual-mode-lite' SD40-2

With a nod to historic preservation that never quite happened, think back to the GE MATE idea (which started as a revival of B unit capital savings but rapidly grew into more), and then expand this with the general theory of road slugs. The key insight is to avoid operation of an 'electrifying' system with straight-electric operation on the wired portion -- you calculate the train factor and units on the basis of self-propelled horsepower, and run the trains and blocks through regardless of overhead power availability. Dual-mode-lite then allows what I call 'punctate electrification', like an expansion of some of the streetcar schemes like the Swiss flywheel system that only connected to electricity at stops. This allows any breaks or gaps in the wire, including permanent gaps for bridges, yards, crossings, etc. to be negotiated using only the onboard power with no compromise in train performance.

Adding battery locomotives with appropriate road-slug-like power connections -- which could and should be AAR-standardized just as HEP has been -- in the way that the FLXdrive locomotive has been used allows the battery-electric to double as a road slug, or hybrid enablement, or (to take a leaf from Iden's approach) carry the pans and primary transformers for dual-mode-lite connection to powered units.

You can then use the 'additional horsepower' for straight electrification for helping or snapping, or assisting acceleration where PSR limited-notch means added speed is not valuable.

You mean, have locomotives set up like they do for slugs, but the power goes from the slug, to the host. It makes sense, they would essentially become the APVs that Amtrak is getting, which have Pans, inverters, and battery packs separate from the locomotive, so no annoying dual mode gear, just the ability to switch from local power source, to aux power source.

It's a little more than that: in order for the trick to work correctly, the current in the 'slug connections' has to be bidirectional and controllable, so that all the synthesis inverters take power as needed from prime movers, batteries, or OHLE/smart third rail. In my opinion the way to implement this on AC units is by 'trainlining' the DC Link current, rather than having multiple AC sources for rectification by individual units. (Both the hydrogen fuel cells and the traction batteries inherently source reasonably high-voltage DC in the first place) Some of the design criteria will quickly become obvious with a little reflection. There has been a considerable development of commercial/OTS equipment suitable for utility HVDC lines and feeders, so the necessary components for 12--=1500V DC Link ought to be easily sourceable when the time comes...

The unit's long hood was essentially a shell upon donation to the ORM, all the hydrogen fuel cell equipment has been stripped out. It does have functioning cab control equipment I am told, so it needs very little work for use as a shove platform. Another proposal is to fit a couple of generator units into the empty long hood for HEP power. In any case, the ORM's intention is to keep what historical fabric remains intact.

Suits me!

Here's how much power you need to have for a normal OTR intermodal operation that you decide to convert into electric trucks. For a fleet of 50 trucks you need to have a powerline capacity of 5 Megawatts into your terminal. Most smaller cities don't even draw that much power. Or in windmill terms it's 4 dedicated for you alone.