Something different: hydrogen-powered trains.

[Gumboots]

World premiere: Alstom’s hydrogen trains enter passenger service in Lower Saxony



These have just been put into main line service in Germany.
The short version is: passenger traffic, 140 km/h top speed (87 mph), 1,000 km range (620 miles).

Basic layout shown here: https://www.alstom.com/coradia-ilint-wo ... cteristics

Alstom is negotiating contracts for more of these units, in several countries. They are (currently) more expensive to buy than equivalent diesels, but cheaper to run, and with the obvious benefits of much lower noise and no trackside pollution (the only output is water vapour).

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Which all got me wondering how they could be classified in RT3. They're not steam, or diesel. They are effectively electric: the hydrogen fuel cells produce electricity, which runs the electric motors. In this respect they are functionally similar to a standard diesel/electric unit, in that they simply replace the diesel/generator source of electricity with a hydrogen fuel cell.

Still, they're definitely not diesel, and they have the advantage of being able to run on standard non-electrified track. This is one of their major selling points for regional lines: much cleaner than diesels, but no need for standard electric train infrastructure.

[Gumboots]

RoR and I ran some basic tests of RT3 engine types. Turns out we can have a fourth category for non-conventional units like the iLint, and the solar-powered train in Byron Bay.

Using a hex value of 03 in the .lco file gives a blank category name, but everything else works normally. So non-conventional locos could be set to 03 to indicate that they aren't steam, or diesel, or conventional electric. These units are still powered by electricity, of course, but can run on normal non-electrified track.

Since they are still powered by electricity, and since there's no way of getting a non-blank category name, and since there are at least two different types of non-conventional units (solar/battery and hydrogen) already in operation, the best way of dealing with them in RT3 is probably to use a suffix on the loco name. Electric cars are commonly classified as either BEV (Battery Electric Vehicle) or FCEV (Fuel Cell Electric Vehicle). These would work just as well for loco names in RT3, so you could have one called "iLint FCEV", for example.