Please find this very interesting link: http://www.railpower.com/

Although these hybrid locomotives are for rail yard switch usage ("goats" in RR-lingo) and thus smallish in horsepower, there may be the day when mainline locos become hybrid, and we see them hauling battery tenders.

Think about it... the diesel-electric locos are a complete hybrid system -without batteries of course. They do a lot, and I mean a lot of regen braking which nowdays is dissipated on resistors, but could be used to charge batteries. They have long coasting stretches. And the added weight of the battery pack, would be of less concern with the ultra-low rolling resistance of the steel wheels and rails.

What do you think?

Hybrid locomotives are even older than the current generation of hybrid cars. Some of the newest generation hybrid locomotives were in service as early as 1997. It's a good idea and they do the job just as well and SO much cleaner than just a straight diesel !!

Actually, diesel-electric locos have been around since the late 50s and early 60's. I'm not sure I would call them clean, since diesels are inherently very, very dirty. In part, how clean they are depends on the type of diesel fuel burned (only low sulphur can result in semi-clean diesels), and whether they have any soot filters or special cats - and most don't. Plus, diesel electirc locos have been (to my knowledge) less efficient than diesel-hydraulic locos. However, few companies (I believ all of them in Germany) have been able to develop torque converters for diesel hydraulic locos with 6-10k hp.
Diesel electric locos are much heavier and much lower power output generally between 1.5k - 3.0k hp per loco, as opposed to diesel hydraulic locos that range from 3 - 12,000 horsies. That's why in the US you see trains hauled by 3-6 engines, whereas in Europe you see trains (if they are at all hauled by diesel locos, a rarity nowadays) hauled by one single locomotive.

My point exactly.
The electric traction motors would receive regen-braking-recovered energy, instead of having to run the diesel engine in a fuel-enrichment mode during acceleration, which is the dirtiest operation cycle for diesels.

Given the fact that the large majority of locomotives have already electric traction motors, it should be relatively straightforward to add on the batteries.
This could lead to the MPG and emissions improvements that we routinely discuss on this forum.

Of course, if we would live in an ideal world, conversion to an all-electric railway system like the one used in Europe would be best.

I believe that GE now makes a more "green" hybrid locomotive with less emissions and better FE.

https://www.getransportation.com/gen...id_default.asp

ex GE employee..