Appreciating the difficulty of fitting batteries of any size within the design of a locomotive, is there any potential to have a 'battery pack' vehicle separate to the locomotive in the future. I'm thinking of a similar vehicle to the power pack vehicles inserted into the Stadler Flirt bi-mode's (which is of course for diesel purposes, not batteries) but on a similar principle. It could be semi-permanently coupled to the locomotive and be charged from it (or on depot).
A future possibility, or a no-hoper?
Roger Ford's e-zine for February has a section on hybrids, which covers a number of the things being tried out here. And then there's
Wabtec's FLXrive:
FLXdrive is Wabtec’s newest development a battery electric freight locomotive. Leveraging decades of application expertise, coupled with industry leading performance optimization, the hybrid consist that is being demonstrated has the capability of saving fuel and reducing emissions.
Wabtec’s FLXdrive battery electric locomotive pilot is part of a grant project with the Calfornia Air Resource Board (CARB), BNSF and the San Joaquin Valley Air Pollution Control District. Wabtec and BNSF will begin proof-of-concept and performance testing in late 2020. BEL is part of California Climate Investments, a statewide program that puts billions of cap-and-trade dollars to work reducing greenhouse gas emissions, strengthening the economy and improving public health and the environment— particularly in disadvantaged communities.
The specification given is confusing, but together with what's in the e-zine you get:
2400 kWh capacity
30-40 minutes discharge time - implying a power of about 4 MW
Charging only by regeneration or shore supply - but it is only a pilot
Intended to operate with two 4400 HP locomotives - this is the USA, after all
Weight (max) 430000 lb (192 t)
Powered axles 4 (out of 6)
I had assumed that the class 93 uses a lithium titanate oxide battery for its high charge/discharge rate, and it does seem that they are used in some bigger hybrid cars and in buses for that reason. Of course the separate vehicle allows a much bigger battery, allowing for a higher output power over a time Li-ion can manage.
But I did think British operators would not accept an add-on of a different kind, and even if the components were redistributed into two identical ones they would dislike running them routinely in pairs. So I can see why it's being tried in the USA - especially if there's grants to be had!